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Smith RW, Ortega DG, Arnett JE, Neltner TJ, Schmidt RJ, Johnson GO, Weir JP, Housh TJ. The effects of sustained, low- and high-intensity isometric tasks on performance fatigability and the perceived responses that contributed to task termination. Eur J Appl Physiol 2024; 124:1587-1599. [PMID: 38165446 DOI: 10.1007/s00421-023-05396-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/05/2023] [Indexed: 01/03/2024]
Abstract
PURPOSE The present study examined the effects of sustained, isometric low- versus high-intensity tasks on time to task failure (TTF), performance fatigability (PF), ratings of perceived exertion (RPE), and the perceived causes of task termination from a post-test questionnaire (PTQ). METHODS Ten men (mean ± SD: age = 21.1 ± 2.3 years; height = 180.2 ± 5.7 cm; body mass = 79.5 ± 8.8 kg) performed maximal voluntary isometric contractions (MVICs) before and after fatiguing, isometric forearm flexion tasks anchored to the torque corresponding to RPE values of 2 (TRQ2FT = 23.8 ± 7.1 N·m) and 8 (TRQ8FT = 60.9 ± 11.4 N·m). In addition, the subjects completed a PTQ which surveyed whether the perceived sensations of fatigue or pain, and/or the psychological factors of loss of focus and motivation contributed to the decision to terminate the task. Repeated measures ANOVAs, Wilcoxon-Signed Rank tests, and Spearman's Rank-Order Correlations were used to analyze the data. RESULTS Across the fatiguing tasks, there were similar decreases in MVIC torque (95.2 ± 20.3 vs. 68.9 ± 15.6 N·m; p < 0.001) and RPE values (p = 0.122) at task failure for TRQ2FT (7.4 ± 2.7) and TRQ8FT (8.9 ± 1.0), but a longer (p = 0.005) TTF for the TRQ2FT (245.0 ± 177.0 s) than TRQ8FT (36.8 ± 11.1 s). CONCLUSIONS Despite reaching task failure, the subjects were able to perform MVICs that were 100-300% greater than the target torque values within seconds of terminating the tasks. Thus, we hypothesized that task failure was not caused by an inability to produce sufficient torque to sustain the tasks, but rather an unwillingness to continue the task.
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Affiliation(s)
- Robert W Smith
- Department of Nutrition and Health Sciences, University of NE - Lincoln, Lincoln, NE, 68510, USA.
| | - Dolores G Ortega
- Department of Nutrition and Health Sciences, University of NE - Lincoln, Lincoln, NE, 68510, USA
| | - Jocelyn E Arnett
- Department of Nutrition and Health Sciences, University of NE - Lincoln, Lincoln, NE, 68510, USA
| | - Tyler J Neltner
- Department of Health and Human Performance, University of Wisconsin-Platteville, Platteville, WI, 53818, USA
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, University of NE - Lincoln, Lincoln, NE, 68510, USA
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, University of NE - Lincoln, Lincoln, NE, 68510, USA
| | - Joseph P Weir
- Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS, 66045, USA
| | - Terry J Housh
- Department of Nutrition and Health Sciences, University of NE - Lincoln, Lincoln, NE, 68510, USA
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Ortega DG, Smith RW, Arnett JE, Neltner TJ, Schmidt RJ, Johnson GO, Housh TJ. Are performance and perceived fatigability dependent on the anchor scheme of fatiguing isometric tasks in men? J Sports Med Phys Fitness 2024:S0022-4707.24.15721-0. [PMID: 38436595 DOI: 10.23736/s0022-4707.24.15721-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
BACKGROUND Ratings of perceived exertion (RPE) can be used to regulate exercise intensity. This study examined the effect of anchor scheme on performance fatigability and neuromuscular responses following fatiguing forearm flexion tasks. METHODS Twelve men (age 20.9±2.2 years; height 179.8±5.3 cm; body mass 80.2±9.9 kg) performed sustained, isometric forearm flexion tasks to failure anchored to RPE=6 (RPEFT) and the torque (TRQFT) that corresponded to RPE=6. Pre-test and post-test maximal voluntary isometric contractions (MVIC) were performed to quantify changes in the amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals. Neuromuscular efficiency (NME) was calculated by dividing normalized torque by normalized EMG AMP. A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated measures ANOVAs were used to compare mean differences for performance fatigability and normalized neuromuscular parameters. RESULTS The RPEFT had a greater TTF than the TRQFT (P<0.001). MVIC and NME decreased from pre-test to post-test following the RPEFT and TRQFT (P<0.05) with no differences between anchor schemes. Following the TRQFT, normalized EMG MPF decreased from pre-test to post-test (P=0.004). Following the RPEFT, normalized MMG MPF increased from pre-test to post-test (P=0.021). There were no changes in normalized EMG AMP or MMG AMP (P>0.05). CONCLUSIONS These findings indicated anchor scheme-specific neuromuscular responses and TTF, despite no difference in performance fatigability. Furthermore, performance fatigability was likely due to peripheral fatigue (based on normalized EMG MPF and NME) following the TRQFT, but peripheral and central fatigue (based on normalized MMG MPF and NME) following the RPEFT.
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Affiliation(s)
- Dolores G Ortega
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska - Lincoln, Lincoln, NE, USA -
| | - Robert W Smith
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska - Lincoln, Lincoln, NE, USA
| | - Jocelyn E Arnett
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska - Lincoln, Lincoln, NE, USA
| | - Tyler J Neltner
- Department of Health and Human Performance, University of Wisconsin - Platteville, Platteville, WI, USA
| | - Richard J Schmidt
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska - Lincoln, Lincoln, NE, USA
| | - Glen O Johnson
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska - Lincoln, Lincoln, NE, USA
| | - Terry J Housh
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska - Lincoln, Lincoln, NE, USA
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Anders JPV, Neltner TJ, Smith RW, Arnett JE, Housh TJ, Schmidt RJ, Johnson GO. Unilateral and Bilateral Isokinetic Leg Extensions Exhibit No Differences in Neuromuscular Excitation Under Maximal and Fatiguing Conditions. J Strength Cond Res 2024; 38:474-480. [PMID: 38090801 DOI: 10.1519/jsc.0000000000004652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
Abstract
Anders, JPV, Neltner, TJ, Smith, RW, Arnett, JE, Housh, TJ, Schmidt, RJ, and Johnson, GO. Unilateral and bilateral isokinetic leg extensions exhibit no differences in neuromuscular activation under maximal and fatiguing conditions. J Strength Cond Res 38(3): 474–480, 2024—The bilateral deficit is a phenomenon where force production during a bilateral (BL) muscle action is less than the sum of force produced when the muscle action is performed unilaterally (UL) with both limbs. The purpose of this study was to compare peak force, electromyographic (EMG) amplitude (AMP), and mean power frequency (MPF) of the nondominant leg between UL and BL isokinetic leg extensions. Eleven recreationally trained men (mean ± SD; age = 20.8 ± 1.7 years; body mass = 84.0 ± 16.2 kg; height = 179.3 ± 7.2 cm) volunteered to participate in this study. The 2 test visits included UL and BL maximal isokinetic leg extensions at 180°·second−1 followed by a fatiguing task of either 50 UL or 25 UL followed immediately by 25 BL (ULBL) maximal, isokinetic leg extensions at 180°·second−1, in random order on separate days. The results demonstrated a significant (p = 0.015,
= 0.460) bilateral deficit in force (UL = 56.29 ± 11.20 kg; BL = 50.32 ± 7.35 kg; d = 0.63; 95% CI [1.42, 10.52]) but no significant bilateral deficit in EMG AMP (p = 0.892,
= 0.002). The peak force during the fatiguing task demonstrated a significant main effect for repetition (p < 0.001,
= 0.943) characterized by a reduced peak force from repetitions 20–50. Similarly, EMG MPF demonstrated a significant main effect for repetition (p < 0.001,
= 0.702) characterized by a reduced EMG MPF from repetitions 35–50. There were no significant effects (p = 0.102–0.387,
= 0.096–0.203) for EMG AMP. These findings suggested that the bilateral deficit was not associated with a neuromuscular deficit and UL muscle actions may be used to potentiate force production of subsequent BL muscle actions.
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Affiliation(s)
- John Paul V Anders
- The Exercise Science Program, Department of Human Sciences, The Ohio State University, Columbus, Ohio; and
| | - Tyler J Neltner
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, The University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Robert W Smith
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, The University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Jocelyn E Arnett
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, The University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Terry J Housh
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, The University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Richard J Schmidt
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, The University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Glen O Johnson
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, The University of Nebraska-Lincoln, Lincoln, Nebraska
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Ortega DG, Housh TJ, Smith RW, Arnett JE, Neltner TJ, Anders JPV, Schmidt RJ, Johnson GO. Effects of a Sustained, Isometric Forearm Flexion Task to Failure on Torque and Neuromuscular Responses at 3 Elbow Joint Angles. J Strength Cond Res 2024; 38:e25-e33. [PMID: 38085633 DOI: 10.1519/jsc.0000000000004599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
ABSTRACT Ortega, DG, Housh, TJ, Smith, RW, Arnett, JE, Neltner, TJ, Anders, JPV, Schmidt, RJ, and Johnson, GO. The effects of a sustained, isometric forearm flexion task to failure on torque and neuromuscular responses at 3 elbow joint angles. J Strength Cond Res 38(1): e25-e33, 2024-This study examined the effects of a sustained, isometric forearm flexion task anchored to torque to task failure on maximal voluntary isometric contraction (MVIC) and neuromuscular responses at 3 elbow joint angles. Eleven women (mean ± SD: age = 20.8 ± 2.7 years, height = 169.3 ± 7.4 cm, body mass = 67.7 ± 6.9 kg) performed two 3s forearm flexion MVICs at elbow joint angles (JAs) of 75°, 100°, and 125° before and after a sustained, isometric forearm flexion task to failure at a fatiguing joint angle of 100° anchored to a torque value that corresponded to a rating of perceived exertion of 8 (RPE = 8). The amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals were recorded from the biceps brachii. Repeated-measures ANOVAs were used to compare mean differences for MVIC and neuromuscular parameters. Collapsed across JAs, MVIC (p < 0.001) and EMG MPF (p = 0.006) pretest values were greater than posttest values. Collapsed across time, EMG MPF at JA75 was greater than JA100 (p < 0.001) and JA125 (p < 0.001), and JA100 was greater (p = 0.007) than JA125. For EMG AMP, there was a fatigue-induced decrease at JA75 (p = 0.003). For neuromuscular efficiency (NME = normalized torque/normalized EMG AMP), there were decreases from pretest to posttest at JA100 (p = 0.002) and JA125 (p = 0.008). There were no significant interactions or main effects for MMG AMP and MMG MPF. From these findings, it was hypothesized that the decline in MVICs at JA75, JA100, and JA125 was due to fatigue-induced metabolic perturbations that resulted in JA-specific neuromuscular responses. Thus, neuromuscular parameters may provide insight into the JA-specific mechanisms of fatigue.
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Affiliation(s)
- Dolores G Ortega
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Terry J Housh
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Robert W Smith
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Jocelyn E Arnett
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Tyler J Neltner
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - John Paul V Anders
- Department of Human Sciences, The Exercise Science Program, The Ohio State University, Columbus, Ohio
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
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Neltner TJ, Sahoo PK, Smith RW, Anders JPV, Arnett JE, Ortega DG, Schmidt RJ, Johnson GO, Natarajan SK, Housh TJ. Effects of High-Intensity, Eccentric-Only Muscle Actions on Serum Biomarkers of Collagen Degradation and Synthesis. J Strength Cond Res 2023; 37:1729-1737. [PMID: 37616533 DOI: 10.1519/jsc.0000000000004457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
ABSTRACT Neltner, TJ, Sahoo, PK, Smith, RW, Anders, JPV, Arnett, JE, Ortega, DG, Schmidt, RJ, Johnson, GO, Natarajan, SK, and Housh, TJ. Effects of high-intensity, eccentric-only muscle actions on serum biomarkers of collagen degradation and synthesis. J Strength Cond Res 37(9): 1729-1737, 2023-The purpose of this study was to examine the effects of high-intensity, eccentric-only muscle actions of the leg extensors on (a) serum biomarkers of collagen degradation (hydroxyproline [HYP] and C-terminal telopeptide of type I collagen [C1M]) and synthesis (pro-c1α1) and (b) the time course of changes in maximal voluntary isometric contraction (MVIC) and ratings of muscle soreness after the eccentric-only exercise bout. Twenty-five recreationally active men (mean ± SD: age = 21.2 ± 2.0 years) completed 5 sets of 10 bilateral, eccentric-only dynamic constant external resistance muscle actions of the leg extensors at a load of 110% of their concentric leg extension 1 repetition maximum. Analysis of variances (p < 0.05) and a priori planned pairwise comparisons using Bonferroni corrected (p < 0.0167) paired t tests were used to examine mean changes in blood biomarkers from baseline to 48 hours postexercise as well as in MVIC and soreness ratings immediately, 24 hours, and 48 hours postexercise. There were increases in HYP (3.41 ± 2.37 to 12.37 ± 8.11 μg·ml-1; p < 0.001) and C1M (2.50 ± 1.05 to 5.64 ± 4.89 μg·L-1; p = 0.003) from preexercise to 48 hours postexercise, but no change in pro-c1α1. Maximal voluntary isometric contraction declined immediately after the exercise bout (450.44 ± 72.80 to 424.48 ± 66.67 N·m; p = 0.002) but recovered 24 hours later, whereas soreness was elevated immediately (6.56 ± 1.58; p < 0.001), 24 hours (3.52 ± 1.53; p < 0.001), and 48 hours (2.60 ± 1.32; p = 0.001) postexercise. The eccentric-only exercise bout induced increases in collagen degradation but had no effect on collagen synthesis. These findings provide information for clinicians to consider when prescribing exercise after an acute injury or surgery.
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Affiliation(s)
- Tyler J Neltner
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
| | - Prakash K Sahoo
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
| | - Robert W Smith
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
| | | | - Jocelyn E Arnett
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
| | - Dolores G Ortega
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
| | - Sathish Kumar Natarajan
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
| | - Terry J Housh
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, Nebraska; and
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Arnett JE, Smith RW, Neltner TJ, Anders JPV, Ortega DG, Housh TJ, Schmidt RJ, Johnson GO. Performance Fatigability and Neuromuscular Responses Are Not Joint Angle Specific Following a Sustained Isometric Forearm Flexion Task Anchored to a High Perceptual Intensity in Women. J Musculoskelet Neuronal Interact 2023; 23:299-307. [PMID: 37654215 PMCID: PMC10483820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Accepted: 07/31/2023] [Indexed: 09/02/2023]
Abstract
OBJECTIVES To examine the effects of joint angle (JA) on maximal voluntary isometric contractions (MVIC) and neuromuscular responses following a sustained, isometric forearm flexion task anchored to a rating of perceived exertion (RPE) of 8 (RPE=8). METHODS Nine women (age: 20.7±2.9 yrs; height: 168.8±7.2 cm; body mass: 66.3±6.8 kg) performed 2,3s forearm flexion MVICs at JAs of 75°, 100°, and 125° prior to and following a sustained, isometric forearm flexion task anchored to RPE=8 to task failure (torque reduced to zero) at JA100. Electromyographic (EMG) and mechanomyographic (MMG) signals were recorded from the biceps brachii. RESULTS The MVIC at JA100 (collapsed across Time) was significantly greater (p<0.05) than JA75 and JA125. The pre-test MVIC was significantly greater (p<0.001) than the post-test. For EMG amplitude (AMP) and EMG mean power frequency (MPF), pre-test values were significantly greater (p<0.05) than the post-test values, with no differences between JAs. For MMG AMP and MMG MPF, there were no significant (p>0.05) differences between Time or JAs. Pre-test neuromuscular efficiency (normalized MVIC/normalized EMG AMP) was significantly greater (p=0.005) than post-test. CONCLUSION Following a sustained, isometric forearm flexion task anchored to RPE=8 at JA100, the fatigue-induced MVIC and neuromuscular responses were not affected by JA.
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Affiliation(s)
- Jocelyn E. Arnett
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Robert W. Smith
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Tyler J. Neltner
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | | | - Dolores G. Ortega
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Terry J. Housh
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Richard J. Schmidt
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Glen O. Johnson
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, USA
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Ortega DG, Housh TJ, Smith RW, Arnett JE, Neltner TJ, Anders JPV, Schmidt RJ, Johnson GO. Fatiguing Joint Angle Does Not Influence Torque and Neuromuscular Responses Following Sustained, Isometric Forearm Flexion Tasks Anchored to Perceptual Intensity in Men. J Funct Morphol Kinesiol 2023; 8:114. [PMID: 37606409 PMCID: PMC10443325 DOI: 10.3390/jfmk8030114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/05/2023] [Accepted: 08/07/2023] [Indexed: 08/23/2023] Open
Abstract
This study examined the effects of joint angle (JA) on maximal voluntary isometric contraction (MVIC) and neuromuscular responses following fatiguing tasks anchored to RPE. Nine men (mean ± SD: age = 20.7 ± 1.2 yrs) performed forearm flexion MVICs at elbow JAs of 75° and 125° before and after sustained, isometric forearm flexion tasks to failure at fatiguing joint angles (FJA) of 75° and 125° anchored to RPE = 8. The amplitude and frequency of the electromyographic and mechanomyographic signals were recorded. Neuromuscular efficiency was calculated by dividing normalized torque by normalized electromyographic amplitude. A dependent t-test was used to assess the mean difference for time to task failure (TTF) between FJA. Repeated measure ANOVAs were used to assess mean differences for pre-test to post-test MVIC and neuromuscular responses. There was no significant difference between FJA for TTF (p = 0.223). The MVIC (collapsed across FJA and MVIC JA) decreased from pre-test to post-test (51.1 ± 5.0 vs. 45.3 ± 5.6 Nm, p < 0.001). Normalized neuromuscular parameters remained unchanged (p > 0.05). The FJA resulted in similar torque and neuromuscular responses, and the decreases in MVIC were not tracked by changes in the neuromuscular parameters. Thus, the neuromuscular parameters were not sensitive to fatigue, and pre-test to post-test measures may be compared between different FJA.
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Affiliation(s)
- Dolores G. Ortega
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska—Lincoln, Lincoln, NE 68510, USA; (D.G.O.)
| | - Terry J. Housh
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska—Lincoln, Lincoln, NE 68510, USA; (D.G.O.)
| | - Robert W. Smith
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska—Lincoln, Lincoln, NE 68510, USA; (D.G.O.)
| | - Jocelyn E. Arnett
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska—Lincoln, Lincoln, NE 68510, USA; (D.G.O.)
| | - Tyler J. Neltner
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska—Lincoln, Lincoln, NE 68510, USA; (D.G.O.)
| | - John Paul V. Anders
- The Exercise Science Program, Department of Human Sciences, The Ohio State University, Columbus, OH 43210, USA
| | - Richard J. Schmidt
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska—Lincoln, Lincoln, NE 68510, USA; (D.G.O.)
| | - Glen O. Johnson
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska—Lincoln, Lincoln, NE 68510, USA; (D.G.O.)
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Salmon OF, Housh TJ, Hill EC, Keller JL, Anders JPV, Johnson GO, Schmidt RJ, Smith CM. Changes in Neuromuscular Response Patterns After 4 Weeks of Leg Press Training During Isokinetic Leg Extensions. J Strength Cond Res 2023; 37:e405-e412. [PMID: 36525527 DOI: 10.1519/jsc.0000000000004418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 09/19/2022] [Indexed: 08/20/2023]
Abstract
ABSTRACT Salmon, OF, Housh, TJ, Hill, EC, Keller, JL, Anders, JPV, Johnson, GO, Schmidt, RJ, and Smith, CM. Changes in neuromuscular response patterns after 4 weeks of leg press training during isokinetic leg extensions. J Strength Cond Res 37(7): e405-e412, 2023-The purpose of this study was to identify velocity-specific changes in electromyographic root mean square (EMG RMS), EMG frequency (EMG MPF), mechanomyographic RMS (MMG RMS), and MMG MPF during maximal unilateral isokinetic muscle actions performed at 60° and 240°·s -1 velocities within the right and left vastus lateralis (VL) after 4 weeks of dynamic constant external resistance (DCER) bilateral leg press training. Twelve resistance-trained men (age: mean ± SD = 21.4 ± 3.6 years) visited the laboratory 3d·wk -1 to perform resistance training consisting of 3 sets of 10 DCER leg presses. Four, three-way analysis of variance were performed to evaluate changes in neuromuscular responses (EMG RMS, EMG MPF, MMG RMS, and MMG MPF) from the right and left VL during 1 single-leg maximal isokinetic leg extension performed at 60° and 240°·s -1 before and after 4 weeks of DCER leg press training ( p < 0.05). The results indicated a 36% increase in EMG RMS for the right leg, as well as a 23% increase in MMG RMS and 10% decrease in MMG MPF after training, collapsed across velocity and leg. In addition, EMG RMS was 65% greater in the right leg than the left leg following training, whereas EMG MPF was 11% greater for the left leg than the right leg throughout training. Thus, 4 weeks of DCER leg press training provides sufficient stimuli to alter the neuromuscular activation process of the VL but not velocity-specific neuromuscular adaptations in trained males.
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Affiliation(s)
- Owen F Salmon
- Robbins College of Health and Human SciencesHuman & Environmental Physiology Laboratory, Department of Health, Human Performance and Recreation Baylor University Waco, Texas
| | - Terry J Housh
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Ethan C Hill
- School of Kinesiology & Physical Therapy, Division of Kinesiology, University of Central Florida, Orlando, Florida; and
| | - Joshua L Keller
- Integrated Laboratory of Exercise and Applied Physiology, Department of Health, Kinesiology, and Sport, College of Education and Professional Studies University of South Alabama, Mobile, Alabama
| | - John Paul V Anders
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Cory M Smith
- Robbins College of Health and Human SciencesHuman & Environmental Physiology Laboratory, Department of Health, Human Performance and Recreation Baylor University Waco, Texas
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Smith RW, Housh TJ, Arnett JE, Anders JPV, Neltner TJ, Ortega DG, Schmidt RJ, Johnson GO. The Effects of Anchor Schemes on Performance Fatigability, Neuromuscular Responses and the Perceived Sensations That Contributed to Task Termination. J Funct Morphol Kinesiol 2023; 8:jfmk8020049. [PMID: 37218845 DOI: 10.3390/jfmk8020049] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/18/2023] [Accepted: 04/20/2023] [Indexed: 05/24/2023] Open
Abstract
The present study examined the effect of anchor schemes on the time to task failure (TTF), performance fatigability, neuromuscular responses, and the perceived sensations that contributed to task termination following the sustained, isometric forearm flexion tasks. Eight women completed sustained, isometric forearm flexion tasks anchored to RPE = 8 (RPEFT) and the torque (TRQFT) that corresponded to RPE = 8. The subjects performed pre-test and post-test maximal isometric contractions to quantify performance fatigability and changes in electromyographic amplitude (EMG AMP) and neuromuscular efficiency (NME). In addition, the subjects completed a post-test questionnaire (PTQ) to quantify the contributions of perceived sensations to task termination. Repeated measure ANOVAs were used to assess the mean differences for TTF, performance fatigability, and neuromuscular responses. Wilcoxon Signed Rank Tests were used to assess the differences between anchor schemes for the average values from the PTQ item scores. For TTF, the RPEFT was longer than the TRQFT (174.9 ± 85.6 vs. 65.6 ± 68.0 s; p = 0.006). Collapsed across the anchor scheme, there were decreases in torque (23.7 ± 5.5 Nm vs. 19.6 ± 4.9 Nm; p < 0.001) and NME (1.00 ± 0.00 vs. 0.76 ± 0.15; p = 0.003). There were no significant (p > 0.577) changes for EMG AMP. For the PTQ, there were no differences (p > 0.05) between anchor schemes. There were, however, inter-individual differences in the response scores. The current findings indicated that performance fatigability was likely due to peripheral fatigue (based on NME), not central fatigue (based on EMG AMP). Furthermore, the use of a PTQ may serve as a simple tool to assess the contributions of perceived sensations to task termination.
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Affiliation(s)
- Robert W Smith
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - Terry J Housh
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - Jocelyn E Arnett
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - John Paul V Anders
- The Exercise Science Program, Department of Human Sciences, The Ohio State University, Columbus, OH 43017, USA
| | - Tyler J Neltner
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - Dolores G Ortega
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - Richard J Schmidt
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - Glen O Johnson
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
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Smith RW, Housh TJ, Arnett JE, Anders JPV, Neltner TJ, Ortega DG, Schmidt RJ, Johnson GO. Utilizing the RPE-Clamp model to examine interactions among factors associated with perceived fatigability and performance fatigability in women and men. Eur J Appl Physiol 2023; 123:1397-1409. [PMID: 36856798 DOI: 10.1007/s00421-023-05163-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 02/17/2023] [Indexed: 03/02/2023]
Abstract
PURPOSE The purpose of the present study was to examine the interactions between perceived fatigability and performance fatigability in women and men by utilizing the RPE-Clamp model to assess the fatigue-induced effects of a sustained, isometric forearm flexion task anchored to RPE = 8 on time to task failure (TTF), torque, and neuromuscular responses. METHODS Twenty adults (10 men and 10 women) performed two, 3 s forearm flexion maximal voluntary isometric contractions (MVICs) followed by a sustained, isometric forearm flexion task anchored to RPE = 8 using the OMNI-RES (0-10) scale at an elbow joint angle of 100°. Electromyographic amplitude (EMG AMP) was recorded from the biceps brachii. Torque and EMG AMP values resulting from the sustained task were normalized to the pretest MVIC. Neuromuscular efficiency was defined as NME = normalized torque/normalized EMG AMP. Mixed factorial ANOVAs and Bonferroni corrected dependent t tests and independent t tests were used to examine differences across time and between sex for torque and neuromuscular parameters. RESULTS There were no differences between the women and men for the fatigue-induced decreases in torque, EMG AMP, or NME, and the mean decreases (collapsed across sex) were 50.3 ± 8.6 to 2.8 ± 2.9% MVIC, 54.7 ± 12.0 to 19.6 ± 5.3% MVIC, and 0.94 ± 0.19 to 0.34 ± 0.16, respectively. Furthermore, there were no differences between the women and men for TTF (251.8 ± 74.1 vs. 258.7 ± 77.9 s). CONCLUSION The results suggested that the voluntary reductions in torque to maintain RPE and the decreases in NME were likely due to group III/IV afferent feedback from peripheral fatigue that resulted in excitation-contraction coupling failure.
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Affiliation(s)
- Robert W Smith
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA.
- , 840 N 14th Street, Lincoln, NE, 68508, USA.
| | - Terry J Housh
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | - Jocelyn E Arnett
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | - John Paul V Anders
- The Exercise Science Program, Department of Human Sciences, The Ohio State University, Columbus, OH, 43017, USA
| | - Tyler J Neltner
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | - Dolores G Ortega
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | - Richard J Schmidt
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | - Glen O Johnson
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
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Neltner TJ, Sahoo PK, Smith RW, Anders JPV, Arnett JE, Schmidt RJ, Johnson GO, Natarajan SK, Housh TJ. Effects of 8 Weeks of Shilajit Supplementation on Serum Pro-c1α1, a Biomarker of Type 1 Collagen Synthesis: A Randomized Control Trial. J Diet Suppl 2022; 21:1-12. [PMID: 36546868 DOI: 10.1080/19390211.2022.2157522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Type 1 collagen is an abundant structural protein with importance to the skin, eyes, bones, ligaments, tendons, and muscles. Shilajit supplementation has been shown to increase gene expression of collagen synthesis, however, it is unclear if increased gene expression translates to increases in circulating levels. Therefore, the purpose of the present study was to examine the effects of 8 weeks of daily supplementation with 500 mg·d-1 and 1000 mg·d-1 of Shilajit versus placebo on serum pro-c1α1, a biomarker of type 1 collagen synthesis. Thirty-five recreationally trained men (mean ± SD: age = 21.1 ± 1.8 yrs; body mass = 80.7 ± 12.4 kg; height = 180.9 ± 6.7 cm) volunteered to participate in this study. Mixed factorial and one-way ANOVAs were used to analyze mean differences between groups, with follow-up t-tests when necessary. Individual subject responses were assessed using the minimal clinically important difference and Chi-squared tests. There were significant (Low dose: p = 0.008, d = 1.2; High dose: p = 0.007, d = 1.3) increases in serum pro-c1α1 from pre- (Low dose: 42.5 ± 12.4 ng·mL-1; High dose: 42.7 ± 12.7 ng·mL-1) to post-supplementation (Low dose: 82.3 ± 46.5 ng·mL-1; High dose: 113.1 ± 78.7 ng·mL-1) for the low and high dose groups, however, no change (p > 0.05) for the placebo group. A greater proportion (p = 0.03) of subjects exhibited increases in pro-c1α1 that exceeded the minimal clinically important difference in the high dose Shilajit group (75%) compared to the placebo group (30%), but no differences (p = 0.06) between the low dose Shilajit group (69%) and placebo. In conclusion, 8 weeks of Shilajit supplementation with 500 and 1000 mg·d-1 increased type 1 collagen synthesis as indicated by serum levels of pro-c1α1.
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Affiliation(s)
- Tyler J Neltner
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE, USA
| | - Prakash K Sahoo
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE, USA
| | - Robert W Smith
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE, USA
| | | | - Jocelyn E Arnett
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE, USA
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE, USA
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE, USA
| | - Sathish Kumar Natarajan
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE, USA
| | - Terry J Housh
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE, USA
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Neltner TJ, Smith RW, Arnett JE, Anders JPV, Keller JL, Housh TJ, Schmidt RJ, Johnson GO. No effect of coactivation on fatigue-induced decreases in isokinetic and isometric torque in healthy young male adults. Hum Mov Sci 2022; 86:103002. [PMID: 36162383 DOI: 10.1016/j.humov.2022.103002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 09/01/2022] [Accepted: 09/16/2022] [Indexed: 12/29/2022]
Abstract
BACKGROUND Antagonist activation may contribute to fatigue-induced decreases in torque while assisting in the maintenance of joint stability. This study utilized a reciprocal, slow velocity (60°·s-1) forearm flexion and extension fatiguing task to examine the contributions of coactivation to torque production at slow and moderate (180°·s-1) velocities, as well as during a maximal voluntary isometric contraction (MVIC). METHODS Twelve recreationally active men (mean ± SD: age = 21.7 ± 1.6 years; body mass = 83.5 ± 8.8 kg; height = 179.4 ± 5.2 cm) completed isokinetic (60 and 180°·s-1) and isometric pre-testing of forearm flexion and extension, followed by 50 maximal, reciprocal, isokinetic muscle actions at 60°·s-1, followed by post-testing. The amplitude (AMP) of the electromyographic (EMG) signals from the biceps and triceps brachii were simultaneously recorded. Torque and EMG AMP were normalized to the corresponding values from the pre-testing peak torque movements. Repeated measures ANOVAs and pairwise comparisons were used to identify mean changes in torque, EMG AMP, and coactivation ratios. RESULTS The torque analyses indicated greater (p < 0.03) decreases for 180°·s-1 (24%) and MVIC (23%) than 60°·s-1 (14%) for forearm flexion. For forearm extension, there were no differences (p > 0.05) in fatigability between velocities. For EMG AMP there were no changes (p > 0.05) from pre- to post-testing for any velocity or movement. There were no changes (p > 0.05) in the coactivation ratio for forearm flexion, but significant increases (13.6 ± 6.6 to 16.9 ± 6.0; p = 0.003) for forearm extension, collapsed across Velocity. CONCLUSIONS There was velocity- and movement-specific fatigability for forearm flexion and extension. The parallel, fatigue-induced EMG AMP responses indicated that coactivation did not contribute to the decreases in torque and would not affect elbow joint stability.
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Affiliation(s)
- Tyler J Neltner
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA.
| | - Robert W Smith
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
| | - Jocelyn E Arnett
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
| | - John Paul V Anders
- Department of Human Sciences, Ohio State University, Columbus, OH 43017, USA
| | - Joshua L Keller
- Department of Health, Kinesiology and Sport, University of South Alabama, Mobile, AL 36688, USA
| | - Terry J Housh
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
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Smith RW, Housh TJ, Anders JPV, Neltner TJ, Arnett JE, Schmidt RJ, Johnson GO. Application of the Ratings of Perceived Exertion-Clamp Model to Examine the Effects of Joint Angle on the Time Course of Torque and Neuromuscular Responses During a Sustained, Isometric Forearm Flexion to Task Failure. J Strength Cond Res 2022; 37:1023-1033. [PMID: 36730581 DOI: 10.1519/jsc.0000000000004357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Robert W Smith
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska
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Smith RW, Anders JPV, Neltner TJ, Arnett JE, Housh TJ, Schmidt RJ, Johnson GO. Individual Torque And Neuromuscular Responses During A Sustained, Isometric Muscle Action Anchored To RPE = 7. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000878048.74470.64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Anders JPV, Neltner TJ, Keller JL, Smith RW, Arnett JE, Housh TJ, Schmidt RJ, Johnson GO. Mode-specific Differences In Exercise-induced Fatigability And The Bilateral Deficit During Isokinetic Leg Extensions In Women. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000882136.17494.1d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Arnett JE, Neltner TJ, Anders JPV, Smith RW, Keller JL, Housh TJ, Schmidt RJ, Johnson GO. Coactivation During Fatiguing, Maximal, Reciprocal, Isokinetic Forearm Flexion And Extension Muscle Actions Using Mechanomyography. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000879876.95850.a7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Neltner TJ, Anders JPV, Smith RW, Arnett JE, Keller JL, Housh TJ, Schmidt RJ, Johnson GO. Coactivation During Fatiguing, Maximal, Reciprocal, Isokinetic Forearm Flexion And Extension Muscle Actions. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000877460.13207.a7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Neltner TJ, Anders JPV, Smith RW, Arnett JE, Keller JL, Housh TJ, Schmidt RJ, Johnson GO. Coactivation does not contribute to fatigue-induced decreases in torque during reciprocal, isokinetic muscle actions. ISOKINET EXERC SCI 2022. [DOI: 10.3233/ies-210229] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Studies of coactivation have typically utilized single movement isometric or isokinetic fatiguing muscle actions. OBJECTIVE: The purpose of the current study was to examine coactivation of the biceps brachii (BB) and triceps brachii (TB) in response to a maximal, reciprocal, isokinetic fatiguing task of the forearm flexors and extensors at slow (60∘/s) and moderate (180∘/s) isokinetic velocities in men. METHODS: Ten men (mean ± SD: age = 21.6 ± 1.3 years) completed 50 consecutive, maximal, reciprocal, isokinetic muscle actions of the right forearm flexors and extensors at 60 and 180∘/s. The amplitude (AMP) and mean power frequency (MPF) contents of the electromyographic (EMG) and mechanomyographic (MMG) signals from the BB and TB were recorded simultaneously throughout the fatiguing task. Repeated measures ANOVAs with Tukey post hocs were used to determine mean differences for the torque and neuromuscular parameters across repetitions. RESULTS: The torque analyses indicated greater fatigability at 180∘/s, compared to 60∘/s (p= 0.02). There were no significant changes in EMG AMP for either muscle during flexion or extension at 60∘/s (p> 0.05). At 180∘/s, there were significant increases in agonist EMG AMP (p= 0.01 to 0.004), however, no changes in antagonist EMG AMP (p> 0.05). For EMG MPF, there were significant decreases during flexion and extension (p< 0.001 to p= 0.02) at both velocities, collapsed across Muscle. There were no significant (p> 0.05) changes across repetition for MMG AMP or MPF. CONCLUSIONS: This study indicated velocity-specific responses to fatigue, with a greater magnitude of fatigability at 180∘/s. Furthermore, despite increases in EMG AMP of the agonist muscles at 180∘/s only, it was not sufficient to alter the ratio of coactivation, likely due to common neural drive between muscles. Thus, the decreases in torque in the present study were not attributable to increases in coactivation.
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Affiliation(s)
- Tyler J. Neltner
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - John Paul V. Anders
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - Robert W. Smith
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - Jocelyn E. Arnett
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - Joshua L. Keller
- Department of Health, Kinesiology and Sport, University of South Alabama, Mobile, AL, USA
| | - Terry J. Housh
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - Richard J. Schmidt
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - Glen O. Johnson
- Department of Nutrition and Health Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
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Smith RW, Housh TJ, Anders JPV, Neltner TJ, Arnett JE, Schmidt RJ, Johnson GO. Time course of changes in torque and neuromuscular parameters during a sustained isometric forearm flexion task to fatigue anchored to a constant rating of perceived exertion. J Musculoskelet Neuronal Interact 2022; 22:455-464. [PMID: 36458383 PMCID: PMC9716304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE This study examined the time course of changes in torque and electromyographic (EMG) and mechanomyographic (MMG) responses during a sustained isometric task anchored to a constant perception of exertion (RPE). METHODS Twelve college-aged men performed an isometric forearm flexion task to failure anchored to RPE=7 (OMNI-RES scale). The amplitude (AMP) and frequency (MPF) of the EMG and MMG signals from the biceps brachii were recorded. Repeated measures ANOVAs were used to examine differences for the normalized (%MVIC) torque and neuromuscular parameters. RESULTS The time to task failure (TTF) was 678.0±468.1s. Torque decreased significantly (p<0.001, ηp2=0.774) across time and all subjects reduced torque to zero. Post-hoc comparisons indicated that the torque values from 20-100% TTF were less than the value at 10% TTF. There were no significant (p>0.05) changes from 10-100% TTF for the EMG and MMG parameters. CONCLUSION We hypothesize that RPE was maintained by various mechanisms throughout the task: group III/IV afferent neurons, adequate blood flow, and a combination of reduced contractile efficiency, collective afferent feedback (group III/IV afferents) from muscles involved with forearm flexion, and motivation that resulted in an initial decrease, plateau, and final decline in torque to zero, respectively.
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Affiliation(s)
- Robert W. Smith
- Department of Nutrition and Human Sciences, University of Nebraska – Lincoln, Lincoln, USA,Corresponding author: Robert W. Smith, 540 N 16th Street, Lincoln, NE 68508-0626, USA E-mail:
| | - Terry J. Housh
- Department of Nutrition and Human Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - John Paul V. Anders
- Department of Nutrition and Human Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Tyler J. Neltner
- Department of Nutrition and Human Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Jocelyn E. Arnett
- Department of Nutrition and Human Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Richard J. Schmidt
- Department of Nutrition and Human Sciences, University of Nebraska – Lincoln, Lincoln, USA
| | - Glen O. Johnson
- Department of Nutrition and Human Sciences, University of Nebraska – Lincoln, Lincoln, USA
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Keller JL, Anders JPV, Neltner TJ, Housh TJ, Schmidt RJ, Johnson GO. Sex differences in muscle excitation and oxygenation, but not in force fluctuations or active hyperemia resulting from a fatiguing, bilateral isometric task. Physiol Meas 2021; 42. [PMID: 34847546 DOI: 10.1088/1361-6579/ac3e86] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 11/30/2021] [Indexed: 01/25/2023]
Abstract
It remains to be fully elucidated if there are sex-specific physiological adjustments within the human neuromuscular and vascular systems that contribute to symptoms of fatigue during a sustained bilateral task. This, in part, is likely due to various limitations in experimental design such as an inability to independently record force fluctuations from each limb.Objective. Therefore, the purpose of the current study was to examine the fatigue-induced changes in muscle excitation, force fluctuations, skeletal muscle tissue saturation (StO2), and muscle blood flow resulting from a sustained, bilateral task.Approach. Thirty healthy, college-aged adults (15 males, 15 females) performed a bilateral leg task at 25% of maximum voluntary isometric (MVIC). Before and after the task, MVICs were completed. Resting and post-task femoral artery blood flow (FABF) were determined. Muscle excitation was quantified as electromyographic amplitude (EMG AMP) from the right and left vastus lateralis. During the task, force fluctuations were determined independently from each leg. The StO2signal was collected with a near-infrared spectroscopy device attached to the right vastus lateralis. The rate of change in these variables was calculated via simple linear regression. The exercise-induced magnitude of change in MVIC (i.e. performance fatigability) and FABF (i.e. active hyperemia) was determined.Main Results. There was no sex difference in the percent decline in MVIC (20.5 ± 20.1% versus 16.4 ± 3.5%;p> 0.05). There were no inter-leg differences in EMG AMP or force fluctuations. The males exhibited a faster rate of increase in EMG AMP (b= 0.13 versusb= 0.08;p< 0.001), whereas the females exhibited a slower rate of decline in StO2(b= -0.049 versusb= -0.080). There was no sex difference in force fluctuations or change in FABF.Significance. Males and females likely have different neuromuscular strategies and muscle characteristics, but these did not elicit a sex difference in performance fatigability.
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Affiliation(s)
- Joshua L Keller
- Integrative Laboratory of Exercise and Applied Physiology (iLEAP), Department of Health, Kinesiology, and Sport, College of Education and Professional Studies, University of South Alabama, Mobile, AL 36606, United States of America
| | - John Paul V Anders
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education, University of Nebraska-Lincoln, Lincoln, NE 68588, United States of America
| | - Tyler J Neltner
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education, University of Nebraska-Lincoln, Lincoln, NE 68588, United States of America
| | - Terry J Housh
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education, University of Nebraska-Lincoln, Lincoln, NE 68588, United States of America
| | - Richard J Schmidt
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education, University of Nebraska-Lincoln, Lincoln, NE 68588, United States of America
| | - Glen O Johnson
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education, University of Nebraska-Lincoln, Lincoln, NE 68588, United States of America
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Neltner TJ, Anders JPV, Keller JL, Smith RW, Housh TJ, Schmidt RJ, Johnson GO. Velocity-Specific Coactivation and Neuromuscular Responses to Fatiguing, Reciprocal, Isokinetic, Forearm Flexion, and Extension Muscle Actions. J Strength Cond Res 2021; 36:649-660. [DOI: 10.1519/jsc.0000000000004190] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Proppe CE, Rivera PM, Hill EC, Housh TJ, Keller JL, Smith CM, Anders JPV, Schmidt RJ, Johnson GO, Cramer JT. The effects of blood flow restriction resistance training on indices of delayed onset muscle soreness and peak power. ISOKINET EXERC SCI 2021. [DOI: 10.3233/ies-210158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Low-load resistance training with blood flow restriction (LL + BFR) attenuated delayed onset muscle soreness (DOMS) under some conditions. OBJECTIVE: The purpose of this study examined the effects of reciprocal concentric-only elbow flexion-extension muscle actions at 30% of peak torque on indices of DOMS. METHODS: Thirty untrained women (mean ± SD; 22 ± 2.4 years) were randomly assigned to 6 training days of LL + BFR (n= 10), low-load non-BFR (LL) (n= 10), or control (n= 10). Participants completed 4 sets (1 × 30, 3 × 15) of submaximal (30% of peak torque), unilateral, isokinetic (120∘s-1) muscle actions. Indices of DOMS including peak power, resting elbow joint angle (ROM), perceived muscle soreness (VAS), and pain pressure threshold (PPT) were assessed. RESULTS: There were no changes in peak power, ROM, or VAS. There was a significant interaction for PPT. Follow-up analyses indicated PPT increased for the LL + BFR condition (Day 5 > Day 2), but did not decrease below baseline. The results of the present study indicated LL + BFR and LL did not induce DOMS for the elbow extensors in previously untrained women. CONCLUSION: These findings suggested LL + BFR and LL concentric-only resistance training could be an effective training modality to elicit muscular adaptation without inducing DOMS.
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Affiliation(s)
| | | | - Ethan C. Hill
- University of Central Florida, Orlando, FL, USA
- Florida Space Institute, Orlando, FL, USA
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Anders JPV, Neltner TJ, Smith RW, Keller JL, Housh TJ, Daugherty FJ, Tempesta MS, Dash AK, Munt DJ, Schmidt RJ, Johnson GO. The effects of phosphocreatine disodium salts plus blueberry extract supplementation on muscular strength, power, and endurance. J Int Soc Sports Nutr 2021; 18:60. [PMID: 34503541 PMCID: PMC8427883 DOI: 10.1186/s12970-021-00456-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 07/01/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Numerous studies have demonstrated the efficacy of creatine supplementation for improvements in exercise performance. Few studies, however, have examined the effects of phosphocreatine supplementation on exercise performance. Furthermore, while polyphenols have antioxidant and anti-inflammatory properties, little is known regarding the influence of polyphenol supplementation on muscular strength, power, and endurance. Thus, the purpose of the present study was to compare the effects of 28 days of supplementation with phosphocreatine disodium salts plus blueberry extract (PCDSB), creatine monohydrate (CM), and placebo on measures of muscular strength, power, and endurance. METHODS Thirty-three men were randomly assigned to consume either PCDSB, CM, or placebo for 28 days. Peak torque (PT), average power (AP), and percent decline for peak torque (PT%) and average power (AP%) were assessed from a fatigue test consisting of 50 maximal, unilateral, isokinetic leg extensions at 180°·s- 1 before and after the 28 days of supplementation. Individual responses were assessed to examine the proportion of subjects that exceeded a minimal important difference (MID). RESULTS The results demonstrated significant (p < 0.05) improvements in PT for the PCDSB and CM groups from pre- (99.90 ± 22.47 N·m and 99.95 ± 22.50 N·m, respectively) to post-supplementation (119.22 ± 29.87 N·m and 111.97 ± 24.50 N·m, respectively), but no significant (p = 0.112) change for the placebo group. The PCDSB and CM groups also exhibited significant improvements in AP from pre- (140.18 ± 32.08 W and 143.42 ± 33.84 W, respectively) to post-supplementation (170.12 ± 42.68 W and 159.78 ± 31.20 W, respectively), but no significant (p = 0.279) change for the placebo group. A significantly (p < 0.05) greater proportion of subjects in the PCDSB group exceeded the MID for PT compared to the placebo group, but there were no significant (p > 0.05) differences in the proportion of subjects exceeding the MID between the CM and placebo groups or between the CM and PCDSB groups. CONCLUSIONS These findings indicated that for the group mean responses, 28 days of supplementation with both PCDSB and CM resulted in increases in PT and AP. The PCDSB, however, may have an advantage over CM when compared to the placebo group for the proportion of individuals that respond favorably to supplementation with meaningful increases in muscular strength.
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Affiliation(s)
- John Paul V Anders
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA.
| | - Tyler J Neltner
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | - Robert W Smith
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | - Joshua L Keller
- Department of Health, Kinesiology and Sport, University of South Alabama, Mobile, AL, 36688, USA
| | - Terry J Housh
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | | | | | - Alekha K Dash
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Omaha, NE, 68178, USA
| | - Daniel J Munt
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Omaha, NE, 68178, USA
| | - Richard J Schmidt
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
| | - Glen O Johnson
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA
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Neltner TJ, Anders JPV, Smith RW, Keller JL, Housh TJ, Schmidt RJ, Johnson GO. Effects Of Maximal, Reciprocal, Isokinetic Fatigue On Coactivation For Forearm Flexion And Extension. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000759288.90085.68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Noboa K, Keller JL, Anders JPV, Neltner T, Housh T, Schmidt R, Johnson GO. Sex Differences In Muscle Excitation And Tissue Oxygenation Are Not Reflected By Global Performance Fatigability. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000759404.80079.d5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Smith RW, Neltner TJ, Anders JPV, Keller JL, Housh TJ, Schmidt RJ, Johnson GO. Fatigue-induced Changes In Coactivation Following Maximal, Isometric, Forearm Flexion To Task-failure. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000759352.29786.b5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Anders JPV, Neltner TJ, Keller JL, Housh TJ, Schmidt RJ, Johnson GO. Are Mode-specific Differences In Performance Fatigability Attributable To Muscle Oxygenation? Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000760340.02066.cb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Proppe CE, Rivera PM, Hill EC, Housh TJ, Keller JL, Smith CM, Anders JPV, Schmidt RJ, Johnson GO, Cramer JT. The Effects Of Blood Flow Restriction Training On Indices Of Doms And Peak Torque. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000759264.76958.8c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hill EC, Housh TJ, Smith CM, Keller JL, Anders JPV, Schmidt RJ, Johnson GO. Acute changes in muscle thickness, edema, and blood flow are not different between low-load blood flow restriction and non-blood flow restriction. Clin Physiol Funct Imaging 2021; 41:452-460. [PMID: 34192417 DOI: 10.1111/cpf.12720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/05/2021] [Accepted: 06/22/2021] [Indexed: 11/28/2022]
Abstract
The purpose of the present study was to examine the acute changes in muscle swelling (as assessed by muscle thickness and echo intensity) and muscle blood flow associated with an acute bout of low-load blood flow restriction (LLBFR) and low-load non-blood flow restriction (LL) exercise. Twenty women (mean ± SD; 22 ± 2years) volunteered to perform an acute exercise bout that consisted of 75 (1 × 30, 3 × 15) isokinetic, reciprocal, concentric-only, submaximal (30% of peak torque), forearm flexion and extension muscle actions. Pretest, immediately after (posttest), and 5-min after (recovery) completing the 75 repetitions, muscle thickness and echo intensity were assessed from the biceps brachii and triceps brachii muscles and muscle blood flow was assessed from the brachial artery. There were no between group differences for any of the dependent variables, but there were significant simple and main effects for muscle and time. Biceps and triceps brachii muscle thickness increased from pretest (2.13 ± 0.39 cm and 1.88 ± 0.40 cm, respectively) to posttest (2.58 ± 0.49 cm and 2.17 ± 0.43 cm, respectively) for both muscles and remained elevated for the biceps brachii (2.53 ± 0.43 cm), but partially returned to pretest levels for the triceps brachii (2.06 ± 0.41 cm). Echo intensity and muscle blood flow increased from pretest (98.0 ± 13.6 Au and 94.5 ± 31.6 ml min-1 , respectively) to posttest (109.2 ± 16.9 Au and 312.2 ± 106.5 ml min-1 , respectively) and pretest to recovery (110.1 ± 18.3 Au and 206.7 ± 92.9 ml min-1 , respectively) and remained elevated for echo intensity, but partially returned to pretest levels for muscle blood flow. The findings of the present study indicated that LLBFR and LL elicited comparable acute responses as a result of reciprocal, concentric-only, forearm flexion and extension muscle actions.
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Affiliation(s)
- Ethan C Hill
- School of Kinesiology & Physical Therapy, Division of Kinesiology, University of Central Florida, Orlando, FL, USA.,Florida Space Institute, University of Central Florida, Orlando, FL, USA
| | - Terry J Housh
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Cory M Smith
- College of Health Sciences, Department of Kinesiology, University of Texas at El Paso, El Paso, TX, USA
| | - Joshua L Keller
- College of Education and Professional Studies, Department of Health, Kinesiology and Sport, University of South Alabama, Mobile, AL, USA
| | - John Paul V Anders
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE, USA
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Anders JPV, Keller JL, Smith CM, Hill EC, Neltner TJ, Housh TJ, Schmidt RJ, Johnson GO. Performance fatigability and the bilateral deficit during maximal, isokinetic leg extensions in men and women. ISOKINET EXERC SCI 2021. [DOI: 10.3233/ies-202178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND: Few studies have examined sex differences in performance fatigability and the bilateral deficit in a dynamic modality. OBJECTIVES: The purpose of this study was to examine: 1) Leg-, mode-, and sex-specific differences in performance fatigability during maximal, dynamic leg extension muscle actions and; 2) the time course of fatigue-induced changes in the bilateral deficit for both men and women. METHODS: Eleven men and 11 women participated in 3 test visits consisting of 50 maximal, concentric, isokinetic leg extensions at 60∘/s. Each visit was randomized to perform either unilateral right leg only (RL), unilateral left leg only (LL), or bilateral (BL) leg extensions. RESULTS: The BL performance fatigability was significantly (p< 0.001) less than RL and LL. Both men and women demonstrated significant (p< 0.001) declines in moment and an attenuation of the bilateral deficit throughout the fatiguing task. There were no differences between sex for performance fatigability (p= 0.128) or the bilateral deficit (p= 0.102). CONCLUSIONS: Unilateral muscle actions were more susceptible to fatigue than BL muscle actions. Men exhibited an earlier decline in moment than women, however, men and women exhibited similar magnitudes and patterns of decline in the bilateral deficit.
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Affiliation(s)
- John Paul V. Anders
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Joshua L. Keller
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Cory M. Smith
- College of Human Sciences, Kinesiology, University of Texas at El Paso, TX, USA
| | - Ethan C. Hill
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL, USA
| | - Tyler J. Neltner
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Terry J. Housh
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Richard J. Schmidt
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Glen O. Johnson
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
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Keller JL, Hill EC, Housh TJ, Smith CM, Anders JPV, Schmidt RJ, Johnson GO. The acute and early phase effects of blood flow restriction training on ratings of perceived exertion, performance fatigability, and muscular strength in women. ISOKINET EXERC SCI 2021. [DOI: 10.3233/ies-204198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Blood flow restriction (BFR) resistance training (RT) has garnered recent interest, but female-specific data remains scarce. OBJECTIVE: The purpose was to examine the effects of 2-wks of low-load concentric, isokinetic, reciprocal forearm flexion and extension training, with and without BFR on perceptual responses, performance fatigability, and muscular strength. METHODS: Twenty women were assigned to a BFRT or a non-BFRT group. Each group trained at 30% of concentric peak moment. Each session consisted of 75 concentric, isokinetic, reciprocal forearm flexion extension muscle actions. RPEs were recorded following each set. Pretest and posttest maximal voluntary isometric contraction (MVIC) force was measured, and percent decline was defined as performance fatigability. RESULTS: The RPE values (p< 0.05) increased across sets. Strength (collapsed across muscle action) increased (p< 0.05) from 0-wk (23.7 ± 3.2 Nm) to 2-wk (26.8 ± 2.7 Nm). Independent of group and muscle action, performance fatigability (p< 0.05) increased from 0-wk (10.9 ± 5.0%) to 2-wk (14.1 ± 4.4%). CONCLUSIONS: 2-wks of low-load concentric, reciprocal forearm flexion and extension training resulted in similar training-induced changes in perceptual responses, performance fatigability, and muscular strength between BFRT and non-BFRT. These findings may reduce concerns of increased perceptual responses following BFRRT compared to non-BFRRT.
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Affiliation(s)
- Joshua L. Keller
- Department of Health, Kinesiology and Sport, College of Education, University of South Alabama, AL, USA
| | - Ethan C. Hill
- Division of Kinesiology, School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL, USA
| | - Terry J. Housh
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education and Human Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - Cory M. Smith
- Human and Environmental Physiology Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, TX, USA
| | - John Paul V. Anders
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education and Human Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - Richard J. Schmidt
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education and Human Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
| | - Glen O. Johnson
- Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, College of Education and Human Sciences, University of Nebraska – Lincoln, Lincoln, NE, USA
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Hill EC, Housh TJ, Smith CM, Keller JL, Schmidt RJ, Johnson GO. High- vs. Low-Intensity Fatiguing Eccentric Exercise on Muscle Thickness, Strength, and Blood Flow. J Strength Cond Res 2021; 35:33-40. [DOI: 10.1519/jsc.0000000000002632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Anders JPV, Keller JL, Neltner TJ, Housh TJ, Schmidt RJ, Johnson GO. Task-specific performance fatigability and the bilateral deficit during isokinetic leg extensions. J Musculoskelet Neuronal Interact 2021; 21:4-12. [PMID: 33657751 PMCID: PMC8020014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVES The purpose of the present study was to compare the fatigue-induced changes in performance fatigability, bilateral deficit, and patterns of responses for the electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF), during unilateral and bilateral maximal, fatiguing leg extensions. METHODS Nine men (Mean±SD; age =21.9±2.4 yrs; height =181.8±11.9 cm; body mass =85.8±6.2 kg) volunteered to perform 50 consecutive maximal, bilateral (BL), unilateral dominant (DL), and unilateral non-dominant (NL) isokinetic leg extensions at 180°·s-1, on 3 separate days. Electromyographic and MMG signals from both vastus lateralis (VL) muscles were recorded. Repeated measures ANOVAs were utilized to examine mean differences in normalized force, EMG AMP, EMG MPF, MMG AMP, MMG MPF and the bilateral deficit. RESULTS The results demonstrated a Condition × Repetition interaction for normalized force (p=0.004, η2p=0.222) and EMG MPF (p=0.034, η2p=0.214) and main effects for Repetition for EMG AMP (p=0.019, η2p=0.231), MMG AMP (p<0.001, η2p=0.8550), MMG MPF (p=0.009, η2p=0.252), and the bilateral deficit (p<0.001, η2p=0.366). CONCLUSIONS The findings demonstrated less performance fatigability during the BL than the unilateral tasks, likely due to a reduced relative intensity via interhemispheric inhibition that attenuated the development of excitation-contraction coupling failure during the BL task.
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Affiliation(s)
- John Paul V. Anders
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA,Corresponding author: John Paul V. Anders, Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA E-mail:
| | - Joshua L. Keller
- Department of Health, Kinesiology and Sport, University of South Alabama, Mobile, USA
| | - Tyler J. Neltner
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
| | - Terry J. Housh
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
| | - Richard J. Schmidt
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
| | - Glen O. Johnson
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
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Neltner TJ, Anders JPV, Smith CM, Keller JL, Hill EC, Housh TJ, Schmidt RJ, Johnson GO. Fatigue-induced Changes In Neuromuscular Responses During Maximal Bilateral Leg Extensions. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000685708.73467.fa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Keller JL, Housh TJ, Anders JPV, Neltner TJ, Hergenradar KJ, Schmidt RJ, Johnson GO. Relative Contributions Of Muscular Strength, Muscle Size, And Tissue Oxygenation To Isometric Performance Fatigability. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000677612.23667.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Keller JL, Housh TJ, Hill EC, Smith CM, Schmidt RJ, Johnson GO. Sex-Related Differences in Performance Fatigability Independent of Blood Flow Following a Sustained Muscle Action at a Low Perceptual Intensity. ACTA ACUST UNITED AC 2020. [DOI: 10.1007/s42978-020-00052-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Anders JPV, Keller JL, Smith CM, Hill EC, Neltner TJ, Housh TJ, Schmidt RJ, Johnson GO. Performance fatigability and neuromuscular responses for bilateral and unilateral leg extensions in men. J Musculoskelet Neuronal Interact 2020; 20:325-331. [PMID: 32877969 PMCID: PMC7493446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVES This study examined performance fatigability and the patterns of neuromuscular responses for electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) during bilateral (BL) and unilateral (UL) maximal, isokinetic leg extensions. METHODS Peak torque for each repetition and EMG and MMG signals from the non-dominant vastus lateralis were recorded in 11 men during 50 BL and UL maximal, concentric, isokinetic leg extensions at 60o·s-1 that were performed on separate days. Separate repeated measures ANOVAs were performed to examine the normalized isokinetic torque and neuromuscular parameters. RESULTS Normalized isokinetic peak torque demonstrated a significant Conditions by Repetition interaction (p<0.001, η2p= 0.594). There were no interactions, but significant main effects for Repetition with increases in EMG AMP (p<0.001; η2p=0.255) and decreases in EMG MPF (p<0.001; η2p=0.650), MMG AMP (p<0.001; η2p=0.402), and MMG MPF (p<0.001; η2p=0.796). In addition, EMG MPF and MMG AMP demonstrated main effects for Condition (p=0.031; η2p=0.387 and p=0.002; η2p=0.64, respectively) with the BL exhibiting greater values than UL leg extensions for both parameters. CONCLUSIONS The current findings indicated greater performance fatigability during UL versus BL leg extensions, but similar patterns of neuromuscular responses consistent with the Muscle Wisdom Hypothesis.
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Affiliation(s)
- John Paul V. Anders
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
| | - Joshua L. Keller
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
| | - Cory M. Smith
- College of Health Sciences, Kinesiology, University of Texas at El Paso, El Paso, USA
| | - Ethan C. Hill
- School of Kinesiology & Physical Therapy, Division of Kinesiology University of Central Florida, Orlando, USA
| | - Tyler J. Neltner
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
| | - Terry J. Housh
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
| | - Richard J. Schmidt
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
| | - Glen O. Johnson
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, USA
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Bergstrom HC, Housh TJ, Dinyer TK, Byrd MT, Jenkins ND, Cochrane-Snyman KC, Succi PJ, Schmidt RJ, Johnson GO, Zuniga JM. Neuromuscular responses of the superficial quadriceps femoris muscles: muscle specific fatigue and inter-individual variability during severe intensity treadmill running. J Musculoskelet Neuronal Interact 2020; 20:77-87. [PMID: 32131371 PMCID: PMC7104590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES This study examined the time course of changes and patterns of responses in electromyographic amplitude (EMG AMP) and EMG mean power frequency (MPF) for the superficial quadriceps muscles during exhaustive treadmill runs within the severe exercise intensity zones (SIZ1 and SIZ2). METHODS The EMG signals for the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) as well as times to exhaustion (Tlim) were recorded in ten runners during two exhaustive treadmill runs (SIZ1 and SIZ2). The composite and individual responses were compared among muscles and between intensities. RESULTS The composite patterns of responses in EMG AMP (linear, quadratic, and cubic increases; r2/R2=0.684-0.848) and EMG MPF (linear, quadratic, and cubic decreases; r2/R2=0.648 - 0.852) for the VL and RF were consistent with neuromuscular fatigue in both zones, but those for the VM were not (quadratic, cubic, and non-significant relationships with responses near baseline). The RF tended to demonstrate greater fatigue (EMG MPF decreased from 80-100% Tlim). There was large inter-individual variability (only 10-60% of responses consistent with composite) in response to fatiguing treadmill running. CONCLUSIONS The current findings support the examination and characterization of neuromuscular fatigue on an intensity, muscle, and subject-by-subject basis.
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Affiliation(s)
- Haley C. Bergstrom
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, USA,Corresponding author: Haley Bergstrom, Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY 40502, USA E-mail:
| | - Terry J. Housh
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, USA
| | - Taylor K. Dinyer
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, USA
| | - M. Travis Byrd
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, USA
| | | | | | - Pasquale J. Succi
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, USA
| | - Richard J. Schmidt
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, USA
| | - Glen O. Johnson
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, USA
| | - Jorge M. Zuniga
- Department of Biomechanics, University of Nebraska-Omaha, Omaha, USA,Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Chile
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Keller JL, Housh TJ, Hill EC, Smith CM, Schmidt RJ, Johnson GO. Are There Sex-Specific Neuromuscular or Force Responses to Fatiguing Isometric Muscle Actions Anchored to a High Perceptual Intensity? J Strength Cond Res 2019; 36:156-161. [PMID: 31860532 DOI: 10.1519/jsc.0000000000003394] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Keller, JL, Housh, TJ, Hill, EC, Smith, CM, Schmidt, RJ, and Johnson, GO. Are there sex-specific neuromuscular or force responses to fatiguing isometric muscle actions anchored to a high perceptual intensity? J Strength Cond Res XX(X): 000-000, 2019-The purpose of this study was to use the ratings of perceived exertion (RPE) clamp model to examine sex-specific changes in neuromuscular responses and force after a sustained isometric leg extension muscle action anchored to RPE = 8. Twenty adults (10 men and 10 women) performed sustained, isometric leg extension muscle actions at RPE = 8. Electromyographic (EMG) and mechanomyographic signals were recorded from the dominant leg. Neuromuscular and force values resulting from the sustained muscle action were normalized to pretest maximal voluntary isometric contractions (MVICs). The level of significance set for the study was p ≤ 0.05. The pretest MVIC was significantly (p < 0.001) greater (averaged across sex) than posttest MVIC force (55.5 ± 10.0 vs. 47.6 ± 11.1 kg). There was a significant (p < 0.01) decrease from pretest (95.4 ± 7.7 Hz) to posttest (76.2 ± 5.9 Hz) in EMG mean power frequency (MPF) for the men. The normalized force (averaged across sex) decreased significantly (p < 0.001) from the initial timepoint (57.1 ± 16.4%) to the final timepoint (44.3 ± 15.7%) of the sustained muscle action. Normalized EMG MPF (averaged across sex) decreased significantly (p = 0.001) from the initial timepoint (96.4 ± 17.5%) to final timepoint (87.8 ± 18.1%). The men and women exhibited similar fatigue-induced changes in force and neuromuscular parameters; therefore, these findings did not indicate different sex-specific responses after the fatiguing task anchored to a high perception of exertion. The force corresponding to RPE = 8 did not match the anticipated value; so, RPE and percentages of MVIC cannot be used interchangeably, and sustained isometric muscle actions anchored to RPE may elicit unique neuromuscular adaptations.
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Affiliation(s)
- Joshua L Keller
- Human Performance Laboratory, Department of Nutrition and Health Sciences, College of Education and Human Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Terry J Housh
- Human Performance Laboratory, Department of Nutrition and Health Sciences, College of Education and Human Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Ethan C Hill
- Division of Kinesiology, School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, Florida
| | - Cory M Smith
- Department of Kinesiology, College of Health Sciences, University of Texas at El Paso, El Paso, Texas 79968
| | - Richard J Schmidt
- Human Performance Laboratory, Department of Nutrition and Health Sciences, College of Education and Human Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Glen O Johnson
- Human Performance Laboratory, Department of Nutrition and Health Sciences, College of Education and Human Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska
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Anders JPV, Keller JL, Smith CM, Hill EC, Neltner TJ, Housh TJ, Schmidt RJ, Johnson GO. Performance fatigability and neuromuscular responses for bilateral versus unilateral leg extensions in women. J Electromyogr Kinesiol 2019; 50:102367. [PMID: 31711012 DOI: 10.1016/j.jelekin.2019.102367] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/18/2019] [Accepted: 10/29/2019] [Indexed: 01/04/2023] Open
Abstract
The purpose of this study was to compare isokinetic peak torque and the patterns of responses for electromyographic (EMG) and mechanomyographic (MMG), amplitude (AMP) and mean power frequency (MPF) for bilateral (BL) versus unilateral (UL), maximal, isokinetic leg extensions. Eleven recreationally trained women (Mean ± SD: age 22.9 ± 0.9 yrs; body mass 60.5 ± 10.1 kg; height 167.2 ± 6.4 cm) performed 50 maximal, BL and UL isokinetic leg extensions at 60° s-1 on separate days. Electromyographic and MMG signals from the vastus lateralis of the nondominant leg were recorded. Five separate 2 (Condition [BL and UL]) × 10 (Repetitions [5-50]) repeated measures ANOVAs were performed to examine normalized EMG AMP, EMG MPF, MMG AMP, MMG MPF, and isokinetic torque. The results indicated no significant interactions or main effects for EMG AMP and MMG AMP. There were significant interactions for normalized isokinetic peak torque (p < 0.001, η2p = 0.493) and MMG MPF (p = 0.003, η2p = 0.234). For EMG MPF, there was no significant interaction, but significant main effects for Condition (p = 0.003, η2p = 0.607) and Repetitions (p < 0.001, η2p = 0.805). The current findings demonstrated greater performance fatigability for UL than BL leg extensions. Both modalities exhibited similar patterns of neuromuscular responses that were consistent with the Muscular Wisdom hypothesis.
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Affiliation(s)
- John Paul V Anders
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA.
| | - Joshua L Keller
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
| | - Cory M Smith
- College of Health Sciences, Kinesiology, University of Texas at El Paso, El Paso, TX 39968, USA
| | - Ethan C Hill
- School of Kinesiology and Physical Therapy, Division of Kinesiology University of Central Florida, Orlando, FL 32816, USA
| | - Tyler J Neltner
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
| | - Terry J Housh
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
| | - Richard J Schmidt
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
| | - Glen O Johnson
- Department of Nutrition and Human Sciences, University of Nebraska- Lincoln, Lincoln, NE 68510, USA
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Smith CM, Housh TJ, Hill EC, Keller JL, Anders JPV, Johnson GO, Schmidt RJ. Variable resistance training versus traditional weight training on the reflex pathway following four weeks of leg press training. Somatosens Mot Res 2019; 36:223-229. [PMID: 31474178 DOI: 10.1080/08990220.2019.1659238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Purpose: The purpose of this study was to examine the changes in reflex-electromechanical delay (EMD) as a result of 2- and 4-wks of variable resistance training (VRT) or dynamic constant external resistance (DCER) leg press training. Material and Methods: Thirty-six men were randomised into either the Control, DCER, or VRT groups. The DCER and VRT groups performed 3 sets of 10 leg press repetitions 3-d·wk-1 for 4-wks. Reflex-EMD was measured at Baseline, Week-2, and Week-4. Results: The reflex-EMD durations decreased from Baseline at Week-2 and Week-4 for the VRT group, but not the DCER or Control groups. The reflex response < electrochemical process < mechanical process < total reflex-EMD for all groups. Conclusions: VRT elicited greater reflex adaptations compared to DCER training which indicated that VRT may be beneficial to incorporate into training or physical therapy programmes for pilots, soldiers, elderly, athletes, or professions that require quick reflexes and response times.
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Affiliation(s)
- Cory M Smith
- Department of Kinesiology, Human and Environmental Physiology Laboratory, University of Texas at El Paso, College of Health Sciences , El Paso , TX , USA
| | - Terry J Housh
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, College of Education and Human Sciences , Lincoln , NE , USA
| | - Ethan C Hill
- School of Kinesiology and Physical Therapy, Division of Kinesiology, University of Central Florida , Orlando , FL , USA
| | - Joshua L Keller
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, College of Education and Human Sciences , Lincoln , NE , USA
| | - John Paul V Anders
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, College of Education and Human Sciences , Lincoln , NE , USA
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, College of Education and Human Sciences , Lincoln , NE , USA
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, College of Education and Human Sciences , Lincoln , NE , USA
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Anders JPV, Smith CM, Keller JL, Hill EC, Housh TJ, Schmidt RJ, Johnson GO. Inter- and Intra-Individual Differences in EMG and MMG during Maximal, Bilateral, Dynamic Leg Extensions. Sports (Basel) 2019; 7:sports7070175. [PMID: 31323817 PMCID: PMC6681382 DOI: 10.3390/sports7070175] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/04/2019] [Accepted: 07/16/2019] [Indexed: 02/07/2023] Open
Abstract
The purpose of this study was to compare the composite, inter-individual, and intra-individual differences in the patterns of responses for electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) during fatiguing, maximal, bilateral, and isokinetic leg extension muscle actions. Thirteen recreationally active men (age = 21.7 ± 2.6 years; body mass = 79.8 ± 11.5 kg; height = 174.2 ± 12.7 cm) performed maximal, bilateral leg extensions at 180°·s−1 until the torque values dropped to 50% of peak torque for two consecutive repetitions. The EMG and MMG signals from the vastus lateralis (VL) muscles of both limbs were recorded. Four 2(Leg) × 19(time) repeated measures ANOVAs were conducted to examine mean differences for EMG AMP, EMG MPF, MMG AMP, and MMG MPF between limbs, and polynomial regression analyses were performed to identify the patterns of neuromuscular responses. The results indicated no significant differences between limbs for EMG AMP (p = 0.44), EMG MPF (p = 0.33), MMG AMP (p = 0.89), or MMG MPF (p = 0.52). Polynomial regression analyses demonstrated substantial inter-individual variability. Inferences made regarding the patterns of neuromuscular responses to fatiguing and bilateral muscle actions should be considered on a subject-by-subject basis.
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Affiliation(s)
- John Paul V Anders
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA.
| | - Cory M Smith
- College of Health Sciences, Kinesiology, University of Texas at El Paso, El Paso, TX 79968, USA
| | - Joshua L Keller
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - Ethan C Hill
- School of Kinesiology & Physical Therapy, Division of Kinesiology, University of Central Florida, Orlando, FL 32816, USA
| | - Terry J Housh
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - Richard J Schmidt
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
| | - Glen O Johnson
- Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA
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Bergstrom HC, Housh TJ, Dinyer TK, Travis Byrd M, Succi PJ, Jenkins ND, Cochrane-Snyman KC, Schmidt RJ, Johnson GO. Time Courses of Changes In Perceptual, Respiratory, and Neuromuscular Responses in the Severe Intensity Domain. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561662.44215.c3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Keller JL, Housh TJ, Hill EC, Smith CM, Schmidt RJ, Johnson GO. Assessment of Performance Fatiguability During Resistance Exercise Anchored to Ratings of Perceived Exertion. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561675.89956.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Smith CM, Housh TJ, Hill EC, Keller JL, Johnson GO, Schmidt RJ. A biosignal analysis for reducing prosthetic control durations: a proposed method using electromyographic and mechanomyographic control theory. J Musculoskelet Neuronal Interact 2019; 19:142-149. [PMID: 31186384 PMCID: PMC6587080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 01/04/2019] [Indexed: 10/27/2022]
Abstract
OBJECTIVES This project proposes a unique methodology utilizing electromyography and mechanomyography to determine the intensity of a desired movement which may be useful in further developing decomposition algorithms for prosthetic controls. METHODS Ten males performed isometric leg extension muscle actions corresponding to 20, 40, 60, 80, and 100% of their maximal voluntary isometric contraction force. The duration and amplitude of the gross lateral movement of the mechanomyographic signal as well as electromechanical delay were measured during each contraction. RESULTS The results indicated that the duration of the gross lateral movement decreased with increases in intensity (20<40=60<80<100% maximal voluntary isometric contraction) and that the amplitude of the gross lateral movement increased with increases in intensity (20<40=60<80<100% maximal voluntary isometric contraction). In addition, electromechanical delay decreased with each increase in intensity. These measurements occurred within 40 ms from the onset of the electromyographic signal. CONCLUSIONS Thus, these measurements may be incorporated into existing prosthetic control algorithms to reduce grasp times and identify the intensity of a movement earlier. In addition, the gross lateral movement and electromechanical delay measurements may provide more intuitive controls for prosthetic users.
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Anders JPV, Smith CM, Hill EC, Keller JL, Housh TJ, Schmidt RJ, Johnson GO. Time Course of Changes in Neuromuscular Parameters During Maximal Bilateral Dynamic Muscle Actions. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561542.89544.0a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hill EC, Housh TJ, Keller JL, Smith CM, Schmidt RJ, Johnson GO. The validity of the EMG and MMG techniques to examine muscle hypertrophy. Physiol Meas 2019; 40:025009. [PMID: 30736032 DOI: 10.1088/1361-6579/ab057e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE The purpose of this investigation was to examine the ability of the electromyographic (EMG) and mechanomyographic (MMG) amplitude versus torque relationships to track group and individual changes in muscle hypertrophy as a result of resistance training. APPROACH Twelve women performed four weeks of forearm flexion blood flow restriction (BFR) resistance training at a frequency of three times per week. The training was performed at an isokinetic velocity of 120° · s-1 with a training load that corresponded to 30% of concentric peak torque. Muscle hypertrophy was determined using ultrasound-based assessments of muscle cross-sectional area from the biceps brachii. Training-induced changes in the slope coefficients of the EMG amplitude and MMG amplitude versus torque relationships were determined from the biceps brachii during incremental (10%-100% of maximum) isometric muscle actions. MAIN RESULTS There was a significant (p < 0.001; d = 2.15) mean training-induced increase in muscle cross-sectional area from 0 week (mean ± SD = 5.86 ± 0.65 cm2) to 4 weeks (7.42 ± 0.80 cm2), a significant (p = 0.023; d = 0.36) decrease in the EMG amplitude versus torque relationship (50.70 ± 20.41 to 43.82 ± 17.76 µV · Nm-1), but no significant (p = 0.192; d = 0.17) change in the MMG amplitude versus torque relationship (0.018 ± 0.009 to 0.020 ± 0.009 m · s-2 · Nm-1). There was, however, great variability for the individual responses for the EMG and MMG amplitude versus torque relationships. SIGNIFICANCE The results of the present study indicated that the EMG amplitude, but not the MMG amplitude versus torque relationship was sensitive to mean changes in muscle cross-sectional area during the early-phase of resistance training. There was, however, great variability for the individual EMG amplitude versus torque relationships that limits its application for identifying individual changes in muscle hypertrophy as a result of BFR.
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Affiliation(s)
- Ethan C Hill
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, 110 Ruth Leverton Hall, Lincoln, NE 68583-0806, United States of America. Author to whom any correspondence should be addressed
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Keller JL, Housh TJ, Hill EC, Smith CM, Schmidt RJ, Johnson GO. The effects of Shilajit supplementation on fatigue-induced decreases in muscular strength and serum hydroxyproline levels. J Int Soc Sports Nutr 2019; 16:3. [PMID: 30728074 PMCID: PMC6364418 DOI: 10.1186/s12970-019-0270-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 01/29/2019] [Indexed: 11/25/2022] Open
Abstract
Background Shilajit is a safe, fluvic mineral complex exudate that is common to Ayurvedic medicine and is composed of fulvic acids, dibenzo-α-pyrones, proteins, and minerals. The purpose of this study was to examine the effects of 8 weeks of Shilajit supplementation at 250 mg·d− 1 (low dose) and 500 mg·d− 1 (high dose) versus placebo on maximal voluntary isometric contraction (MVIC) strength, concentric peak torque, fatigue-induced percent decline in strength, and serum hydroxyproline (HYP). Methods Sixty-three recreationally-active men (\documentclass[12pt]{minimal}
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\begin{document}$$ \overline{X} $$\end{document}X¯ ± SD: 21.2 ± 2.4 yr.; 179.8 ± 6.3 cm; 83.1 ± 12.7 kg) volunteered to participate in this study. The subjects were randomly assigned to the high dose, low dose, or placebo group (each group: n = 21). During pre-supplementation testing, the subjects performed 2 pretest MVICs, 2 sets of 50 maximal, bilateral, concentric isokinetic leg extensions at 180°·s− 1 separated by 2-min of rest, and 2 posttest MVICs. Following 8 weeks of supplementation, the subjects repeated the pre-supplementation testing procedures. In addition, the groups were dichotomized at the 50th percentile based on pre-supplementation MVIC and baseline HYP. Mixed model ANOVAs and ANCOVAs were used to statistically analyze the dependent variables for the total groups (n = 21 per group) as well as dichotomized groups. Results For the upper 50th percentile group, the post-supplementation adjusted mean percent decline in MVIC was significantly less for the high dose group (8.9 ± 2.3%) than the low dose (17.0 ± 2.4%; p = 0.022) and placebo (16.0 ± 2.4%; p = 0.044) groups. There was no significant (p = 0.774) difference, however, between the low dose and placebo groups. In addition, for the upper 50th percentile group, the adjusted mean post-supplementation baseline HYP for the high dose group (1.5 ± 0.3 μg·mL− 1) was significantly less than both the low dose (2.4 ± 0.3 μg·mL− 1; p = 0.034) and placebo (2.4 ± 0.3 μg·mL− 1, p = 0.024) groups. Conclusions The results of the present study demonstrated that 8 weeks of PrimaVie® Shilajit supplementation at 500 mg·d− 1 promoted the retention of maximal muscular strength following the fatiguing protocol and decreased baseline HYP. Thus, PrimaVie® Shilajit supplementation at 500 mg·d− 1 elicited favorable muscle and connective tissue adaptations.
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Affiliation(s)
- Joshua L Keller
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska - Lincoln, 110 Ruth Leverton Hall, Lincoln, NE, 68583-0806, USA.
| | - Terry J Housh
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska - Lincoln, 110 Ruth Leverton Hall, Lincoln, NE, 68583-0806, USA
| | - Ethan C Hill
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska - Lincoln, 110 Ruth Leverton Hall, Lincoln, NE, 68583-0806, USA
| | - Cory M Smith
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska - Lincoln, 110 Ruth Leverton Hall, Lincoln, NE, 68583-0806, USA
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska - Lincoln, 110 Ruth Leverton Hall, Lincoln, NE, 68583-0806, USA
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska - Lincoln, 110 Ruth Leverton Hall, Lincoln, NE, 68583-0806, USA
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Keller JL, Housh TJ, Smith CM, Hill EC, Schmidt RJ, Johnson GO. Sex-Related Differences in the Accuracy of Estimating Target Force Using Percentages of Maximal Voluntary Isometric Contractions vs. Ratings of Perceived Exertion During Isometric Muscle Actions. J Strength Cond Res 2019; 32:3294-3300. [PMID: 29176386 DOI: 10.1519/jsc.0000000000002210] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Keller, JL, Housh, TJ, Smith, CM, Hill, EC, Schmidt, RJ, and Johnson, GO. Sex-related differences in the accuracy of estimating target force using percentages of maximal voluntary isometric contractions vs. ratings of perceived exertion during isometric muscle actions. J Strength Cond Res 32(11): 3294-3300, 2018-The purpose of this study was to examine sex-related differences in the accuracy of estimating actual target force and to compare the accuracy of estimating actual target force using percentages of maximal voluntary isometric contraction (MVIC) or ratings of perceived exertion (RPE) values during isometric leg flexion and leg extension muscle actions. Twenty adults, 10 women and 10 men, (mean ± SD age: 22.9 ± 2.9 years) completed pretest MVICs to calculate actual target force values at 10, 30, 50, 70, and 90% of MVIC. Additional trials were then randomized for estimating actual target force using percentages of MVIC or RPE values during isometric leg flexion or leg extension. For isometric leg flexion, the women and men overestimated (p ≤ 0.05) the actual target force at 10% for the percentage of MVIC and RPE trials and underestimated the actual target force at 90% for the RPE trial. For isometric leg extension, the women overestimated the actual target force at 10% for the percentage of MVIC trial and RPE trial. The men overestimated actual target force at 10 and 30% for the percentage of MVIC trial and overestimated actual target force at 10% during the RPE trial for isometric leg extension. Also, the men underestimated actual target force at 90% for both the percentage of MVIC trial and RPE trial. Men require more familiarization than women to accurately estimate isometric leg extension force values. Caution should be used when estimating force production as a percentage of MVIC or RPE value for training prescriptions.
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Affiliation(s)
- Joshua L Keller
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska
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Hill EC, Housh TJ, Smith CM, Keller JL, Schmidt RJ, Johnson GO. The Contributions of Arterial Cross-Sectional Area and Time-Averaged Flow Velocity to Arterial Blood Flow. J Med Ultrasound 2019; 26:186-193. [PMID: 30662149 PMCID: PMC6314092 DOI: 10.4103/jmu.jmu_20_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 01/02/2018] [Indexed: 11/09/2022] Open
Abstract
Background: Ultrasound has been used for noninvasive assessments of endothelial function in both clinical and athletic settings and to identify changes in muscle blood flow in response to exercise, nutritional supplementation, and occlusion. The purposes of the present study were to examine the reliability and relative contributions of arterial cross-sectional area and time-averaged flow velocity to predict muscle blood flow as a result of fatiguing exercise in men and women. Methods: Eighteen healthy men and 18 healthy women performed 50 consecutive eccentric repetitions of the elbow flexors at 60% of their pretest eccentric peak torque at a velocity of 180° s−1. Test-retest reliability and stepwise linear regression analyses were performed to determine the ability of arterial cross-sectional area and time-averaged flow velocity to predict brachial artery muscle blood flow for the men, women, and combined sample. Results: There was no systematic test versus retest mean differences (P > 0.05) for any of the ultrasound determined variables. The two-variable regression models significantly improved the ability to predict muscle blood flow and were associated with smaller standard error of the estimates (3.7%–10.1% vs. 16.8%–37.0% of the mean baseline muscle blood flow values) compared to the one-variable models. Conclusions: The findings of the present study supported the use of ultrasound for reliable assessments of arterial diameter, arterial cross-sectional area, time-averaged flow velocity, and muscle blood flow from the brachial artery in men and women. Furthermore, time-averaged flow velocity was a more powerful predictor of muscle blood flow than arterial cross-sectional area.
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Affiliation(s)
- Ethan C Hill
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68505, USA
| | - Terry J Housh
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68505, USA
| | - Cory M Smith
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68505, USA
| | - Joshua L Keller
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68505, USA
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68505, USA
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68505, USA
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