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Malleron T, Har-Nir I, Vigotsky AD, Halperin I. Rating of perceived effort but relative to what? A comparison between imposed and self-selected anchors. PSYCHOLOGY OF SPORT AND EXERCISE 2023; 66:102396. [PMID: 37665858 DOI: 10.1016/j.psychsport.2023.102396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 09/06/2023]
Abstract
PURPOSE Collecting reliable and valid rating of perceived effort (RPE) data requires properly anchoring the scales' upper limits (i.e., the meaning of 10 on a 0-10 scale). Yet, despite their importance, anchoring procedures remain understudied and theoretically underdeveloped. Here we propose a new task-based anchoring procedure that distinguishes between imposed and self-selected anchors. In the former, researchers impose on participants a specific task as the anchor; in the latter, participants choose the most effortful task experienced or imaginable as the anchor. We compared the impact of these conceptually different anchoring procedures on RPE. METHODS Twenty-five resistance-trained participants (13 females) attended a familiarization and two randomized experimental sessions. In both experimental sessions, participants performed non-fatiguing and fatiguing isometric maximal voluntary contraction (MVC) protocols with the squat followed by the gripper or vice versa. After each MVC, participants reported their RPE on a 0-10 scale relative to an imposed anchor of the performed task (e.g., gripper MVCs anchored to a gripper MVC) or to a self-selected anchor. RESULTS In the non-fatiguing condition, imposed anchors yielded greater RPEs than self-selected anchors for both the squat [on average, 9.4 vs. 5.5; Δ(CI95%) = 3.9 (3.2, 4.5)] and gripper [9.4 vs. 3.9; Δ = 5.5 (4.7, 6.3)]. Similar results were observed in the fatiguing condition for both the squat [9.7 vs. 6.9; Δ = 2.8 (2.1, 3.5)] and gripper [9.7 vs. 4.5; Δ = 5.2 (4.3, 5.9)]. CONCLUSIONS We found large differences in RPE between the two anchors, independent of exercises and fatigue state. These findings provide a basis for further development and refinement of anchoring procedures and highlight the importance of selecting, justifying, and consistently applying the chosen anchors.
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Affiliation(s)
- Tomer Malleron
- Department of Health Promotion, School of Public Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel; Sylvan Adams Sports Institute, Tel Aviv University, Tel-Aviv, Israel
| | - Itai Har-Nir
- Department of Health Promotion, School of Public Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel; Sylvan Adams Sports Institute, Tel Aviv University, Tel-Aviv, Israel
| | - Andrew D Vigotsky
- Departments of Biomedical Engineering and Statistics, Northwestern University, Evanston, USA
| | - Israel Halperin
- Department of Health Promotion, School of Public Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel; Sylvan Adams Sports Institute, Tel Aviv University, Tel-Aviv, Israel.
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Balci G, As H, Colakoglu M, Ozkaya O. Accuracy, reliability and segmental error relationship during a Wingate all-out test. Sci Sports 2022. [DOI: 10.1016/j.scispo.2021.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Maciejczyk M, Michailov ML, Wiecek M, Szymura J, Rokowski R, Szygula Z, Beneke R. Climbing-Specific Exercise Tests: Energy System Contributions and Relationships With Sport Performance. Front Physiol 2022; 12:787902. [PMID: 35140627 PMCID: PMC8819085 DOI: 10.3389/fphys.2021.787902] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/22/2021] [Indexed: 01/28/2023] Open
Abstract
PurposeThe aim of the study was to evaluate distinct performance indicators and energy system contributions in 3 different, new sport-specific finger flexor muscle exercise tests.MethodsThe tests included the maximal strength test, the all-out test (30 s) as well as the continuous and intermittent muscle endurance test at an intensity equaling 60% of maximal force, which were performed until target force could not be maintained. Gas exchange and blood lactate were measured in 13 experienced climbers during, as well as pre and post the test. The energy contribution (anaerobic alactic, anaerobic lactic, and aerobic) was determined for each test.ResultsThe contribution of aerobic metabolism was highest during the intermittent test (59.9 ± 12.0%). During continuous exercise, this was 28.1 ± 15.6%, and in the all-out test, this was 19.4 ± 8.1%. The contribution of anaerobic alactic energy was 27.2 ± 10.0% (intermittent), 54.2 ± 18.3% (continuous), and 62.4 ± 11.3% (all-out), while anaerobic lactic contribution equaled 12.9 ± 6.4, 17.7 ± 8.9, and 18.2 ± 9.9%, respectively.ConclusionThe combined analysis of performance predictors and metabolic profiles of the climbing test battery indicated that not only maximal grip force, but also all-out isometric contractions are equally decisive physical performance indices of climbing performance. Maximal grip force reflects maximal anaerobic power, while all-out average force and force time integral of constant isometric contraction at 60% of maximal force are functional measures of anaerobic capacity. Aerobic energy demand for the intermittent exercise is dominated aerobic re-phosphorylation of high-energy phosphates. The force-time integral from the intermittent test was not decisive for climbing performance.
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Affiliation(s)
- Marcin Maciejczyk
- Department of Physiology and Biochemistry, Faculty of Physical Education and Sport, University of Physical Education, Kraków, Poland
- *Correspondence: Marcin Maciejczyk,
| | | | - Magdalena Wiecek
- Department of Physiology and Biochemistry, Faculty of Physical Education and Sport, University of Physical Education, Kraków, Poland
| | - Jadwiga Szymura
- Department of Clinical Rehabilitation, Faculty of Motor Rehabilitation, University of Physical Education, Kraków, Poland
| | - Robert Rokowski
- Department of Alpinism and Tourism, Faculty of Tourism and Recreation, University of Physical Education, Kraków, Poland
| | - Zbigniew Szygula
- Department of Sports Medicine and Human Nutrition, Faculty of Physical Education and Sport, University of Physical Education, Kraków, Poland
| | - Ralph Beneke
- Institute of Sport Science and Motology, Philipps University, Marburg, Germany
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Reliability of Alpine Ski Racing-Specific Field Test: The 80s-Slide-Test. Int J Sports Physiol Perform 2021; 16:1545-1550. [PMID: 33883292 DOI: 10.1123/ijspp.2019-0696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/22/2020] [Accepted: 11/23/2020] [Indexed: 11/18/2022]
Abstract
PURPOSE The purpose of this study was to determine the test-retest reliability of the 80s-slide-test in well-trained alpine ski racers. METHODS The sample consisted of 8 well-trained alpine ski racers (age = 17.8 [0.7] y old; height = 1.80 [0.09] m; body mass = 72.1 [9.5] kg) who performed a lab-based maximal graded test on cycle ergometer and three 80s-slide-tests in 4 separate sessions. The 80s-slide-test consisting of maximal push-offs performed for 80s on a 8-ft slide board. Oxygen uptake (V˙O2) and heart rate (HR) were recorded continuously. Blood lactate ([La]b) was determined immediately prerun, followed by 3 minutes postrun. Three minutes after the completion of the session, the subjects were asked to indicate their rate of perceived exertion using Borg scale ranging from 6 to 20. Total and every 10s mean push-offs number were assessed by camera. Typical errors of measurement, intraclass correlation coefficients, and smallest worthwhile change were calculated. RESULTS The 80s-slide-test showed strong reliability for total push-offs number, V˙O2peak, V˙O2mean, HRpeak, and HRmean. Δ[La]b, fatigue index, and the rate of perceived exertion were moderately reliable. CONCLUSION The 80s-slide-test is a reliable test for well-trained alpine ski racers and can be used easily by trainers.
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Li S, Zhang J, Wang C, Zhu X, Shi H. Affective Response and Enjoyment to Acute High-Intensity Training with Different Intervals in Young and Obese Females. THE ASIAN JOURNAL OF KINESIOLOGY 2019. [DOI: 10.15758/ajk.2019.21.2.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Nitzsche N, Baumgärtel L, Maiwald C, Schulz H. Reproducibility of Blood Lactate Concentration Rate under Isokinetic Force Loads. Sports (Basel) 2018; 6:sports6040150. [PMID: 30463301 PMCID: PMC6315458 DOI: 10.3390/sports6040150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/05/2018] [Accepted: 11/15/2018] [Indexed: 11/30/2022] Open
Abstract
(1) Background: Maximum isokinetic force loads show strongly increased post-load lactate concentrations and an increase in the maximum blood lactate concentration rate (V˙Lamax), depending on load duration. The reproducibility of V˙Lamax must be known to be able to better assess training-related adjustments of anaerobic performance using isokinetic force tests. (2) Methods: 32 subjects were assigned to two groups and completed two unilateral isokinetic force tests (210° s−1, Range of Motion 90°) within seven days. Group 1 (n = 16; age 24.0 ± 2.8 years, BMI 23.5 ± 2.6 kg m−2, training duration: 4.5 ± 2.4 h week−1) completed eight repetitions and group 2 (n = 16; age 23.7 ± 1.9 years, BMI 24.6 ± 2.4 kg m−2, training duration: 5.5 ± 2.1 h week−1) completed 16 repetitions. To determine V˙Lamax, capillary blood (20 µL) was taken before and immediately after loading, and up to the 9th minute post-load. Reproducibility and variability was determined using Pearson and Spearman correlation analyses, and variability were determined using within-subject standard deviation (Sw) and Limits of Agreement (LoA) using Bland Altman plots. (3) Results: The correlation of V˙Lamax in group 1 was r = 0.721, and in group 2 r = 0.677. The Sw of V˙Lamax was 0.04 mmol L−1 s−1 in both groups. In group 1, V˙Lamax showed a systematic bias due to measurement repetition of 0.02 mmol L−1 s−1 in an interval (LoA) of ±0.11 mmol L−1 s−1. In group 2, a systematic bias of −0.008 mmol L−1 s−1 at an interval (LoA) of ±0.11 mmol L−1 s−1 was observed for repeated measurements of V˙Lamax. (4) Conclusions: Based on the existing variability, a reliable calculation of V˙Lamax seems to be possible with both short and longer isokinetic force loads. Changes in V˙Lamax above 0.11 mmol L−1 s−1 due to training can be described as a non-random increase or decrease in V˙Lamax.
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Affiliation(s)
- Nico Nitzsche
- Technische Universität Chemnitz, Center of Sport and Health Promotion, 09126 Chemnitz, Germany.
| | - Lutz Baumgärtel
- Technische Universität Chemnitz, Institute of Human Movement Science and Health, 09126 Chemnitz, Germany.
| | - Christian Maiwald
- Technische Universität Chemnitz, Institute of Human Movement Science and Health, 09126 Chemnitz, Germany.
| | - Henry Schulz
- Technische Universität Chemnitz, Institute of Human Movement Science and Health, 09126 Chemnitz, Germany.
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Tong TK, Zhang H, Shi H, Liu Y, Ai J, Nie J, Kong Z. Comparing Time Efficiency of Sprint vs. High-Intensity Interval Training in Reducing Abdominal Visceral Fat in Obese Young Women: A Randomized, Controlled Trial. Front Physiol 2018; 9:1048. [PMID: 30123136 PMCID: PMC6085472 DOI: 10.3389/fphys.2018.01048] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 07/13/2018] [Indexed: 11/13/2022] Open
Abstract
Introduction: High-intensity interval training (HIIT) is an emerging lifestyle intervention strategy for controlling obesity. HIIT consisted of brief all-out supramaximal sprint intervals was termed as sprint interval training (SIT). This study was designed to examine the time-efficient characteristics of SIT in reducing abdominal visceral fat. Methods: A randomized controlled trial was conducted to compare the specific adaptations of SIT (80 × 6 s all-out cycle sprints interspersed with 9 s passive recovery) with those resulting from a HIIT regimen with training volume relatively higher (repeated 4 min bouts of cycling at 90% V˙ O2max alternated with 3 min rest, until the work of 400KJ was achieved), and with those of nonexercising control counterparts (CON). Forty-six obese young women (body fat percentage ≥30) received either SIT (n = 16), HIIT (n = 16), or no training (n = 14), 3-4 sessions per week, for 12 weeks. The abdominal visceral fat area (AVFA) and abdominal subcutaneous fat area (ASFA) of the participants were measured through computed tomography scans pre-intervention and post-intervention. Total fat mass and the fat mass of the android, gynoid, and trunk regions were assessed through dual-energy X-ray absorptiometry. Results: Following the intervention, abdominal visceral and subcutaneous fat were reduced markedly (p < 0.05). The reduction in AVFA (-6.31, -9.7 cm2) was not different between SIT and HIIT (p > 0.05), while the reduction in ASFA (-17.4, -40.7 cm2) in SIT was less than that in HIIT (p < 0.05). Less reduction in the fat mass of the trunk (-1.2, -2.0 kg) region was also found in SIT, while the reductions in fat percentage (-1.9%, -2.0%), total fat mass (-2.0, -2.8 kg), and fat mass of the android (-0.2, -0.2 kg), and gynoid (-0.4, -0.3 kg) regions did not differ between the two regimes (p > 0.05). In contrast, the increase in V˙ O2max was significant greater following the SIT than HIIT (p < 0.01). No variable changed in CON. Conclusion: Such findings suggest that the lower training load and exercise time commitments of the SIT regime could optimize the time-efficiency advantage of the traditional HIIT, facilitating the abdominal visceral fat reduction in obese young women.
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Affiliation(s)
- Tomas K Tong
- Department of Physical Education, Hong Kong Baptist University, Kowloon, Hong Kong
| | - Haifeng Zhang
- Physical Education College, Hebei Normal University, Shijiazhuang, China.,Provincial Key Lab of Measurement and Evaluation in Human Movement and Bio-Information, Hebei Normal University, Shijazhuang, China
| | - Hongru Shi
- Physical Education College, Hebei Normal University, Shijiazhuang, China.,Provincial Key Lab of Measurement and Evaluation in Human Movement and Bio-Information, Hebei Normal University, Shijazhuang, China
| | - Yang Liu
- Physical Education College, Hebei Normal University, Shijiazhuang, China.,Provincial Key Lab of Measurement and Evaluation in Human Movement and Bio-Information, Hebei Normal University, Shijazhuang, China
| | - Jingwen Ai
- Physical Education College, Hebei Normal University, Shijiazhuang, China.,Provincial Key Lab of Measurement and Evaluation in Human Movement and Bio-Information, Hebei Normal University, Shijazhuang, China
| | - Jinlei Nie
- School of Physical Education and Sports, Macao Polytechnic Institute, Macau, Macau
| | - Zhaowei Kong
- Faculty of Education, University of Macau, Taipa, Macau
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Alhammoud M, Morel B, Girard O, Racinais S, Sevrez V, Germain A, Chamu T, Hautier C. Hypoxia and Fatigue Impair Rapid Torque Development of Knee Extensors in Elite Alpine Skiers. Front Physiol 2018; 9:962. [PMID: 30140231 PMCID: PMC6094991 DOI: 10.3389/fphys.2018.00962] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 06/29/2018] [Indexed: 01/20/2023] Open
Abstract
This study examined the effects of acute hypoxia on maximal and explosive torque and fatigability in knee extensors of skiers. Twenty-two elite male alpine skiers performed 35 maximal, repeated isokinetic knee extensions at 180°s-1 (total exercise duration 61.25 s) in normoxia (NOR, FiO2 0.21) and normobaric hypoxia (HYP, FiO2 0.13) in a randomized, single-blind design. Peak torque and rate of torque development (RTD) from 0 to 100 ms and associated Vastus Lateralis peak EMG activity and rate of EMG rise (RER) were determined for each contraction. Relative changes in deoxyhemoglobin concentration of the VL muscle were monitored by near-infrared spectroscopy. Peak torque and peak EMG activity did not differ between conditions and decreased similarly with fatigue (p < 0.001), with peak torque decreasing continuously but EMG activity decreasing significantly after 30 contractions only. Compared to NOR, RTD, and RER values were lower in HYP during the first 12 and 9 contractions, respectively (both p < 0.05). Deoxyhemoglobin concentration during the last five contractions was higher in HYP than NOR (p = 0.050) but the delta between maximal and minimal deoxyhemoglobin for each contraction was similar in HYP and NOR suggesting a similar muscle O2 utilization. Post-exercise heart rate (138 ± 24 bpm) and blood lactate concentration (5.8 ± 3.1 mmol.l-1) did not differ between conditions. Arterial oxygen saturation was significantly lower (84 ± 4 vs. 98 ± 1%, p < 0.001) and ratings of perceived exertion higher (6 ± 1 vs. 5 ± 1, p < 0.001) in HYP than NOR. In summary, hypoxia limits RTD via a decrease in neural drive in elite alpine skiers undertaking maximal repeated isokinetic knee extensions, but the effect of hypoxic exposure is negated as fatigue develops. Isokinetic testing protocols for elite alpine skiers should incorporate RTD and RER measurements as they display a higher sensitivity than peak torque and EMG activity.
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Affiliation(s)
- Marine Alhammoud
- Inter-university Laboratory of Human Movement Biology (EA 7424), Claude Bernard University Lyon 1, Lyon, France.,French Ski Federation, Annecy, France
| | - Baptiste Morel
- Laboratory "Movement, Interactions, Performance" (EA 4334), Le Mans University, Le Mans, France
| | - Olivier Girard
- School of Psychology and Exercise Science, Murdoch University, Perth, WA, Australia.,Athlete Health and Performance Research Centre, Aspetar Orthopedic and Sports Medicine Hospital, Doha, Qatar
| | - Sebastien Racinais
- Athlete Health and Performance Research Centre, Aspetar Orthopedic and Sports Medicine Hospital, Doha, Qatar.,Laboratory Sport, Expertise and Performance, French Institute of Sport (INSEP), Paris, France
| | - Violaine Sevrez
- French National Center for Scientific Research, Institute of Movement Sciences, Aix-Marseille University, Marseille, France
| | | | - Thomas Chamu
- Orthopedic and Sports Medicine Hospital La Sauvegarde, Lyon, France
| | - Christophe Hautier
- Inter-university Laboratory of Human Movement Biology (EA 7424), Claude Bernard University Lyon 1, Lyon, France
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Doix ACM, Wachholz F, Marterer N, Immler L, Insam K, Federolf PA. Is the cross-over effect of a unilateral high-intensity leg extension influenced by the sex of the participants? Biol Sex Differ 2018; 9:29. [PMID: 29954447 PMCID: PMC6022493 DOI: 10.1186/s13293-018-0188-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/13/2018] [Indexed: 12/02/2022] Open
Abstract
Background While performing a unilateral muscle contraction, electrical muscle activity also arises in the contralateral homologous muscle, muscle group, or limb. When the muscle contraction induces muscle fatigue, females show not only a greater resistance than males but also a reduced contralateral muscle activation. The study aimed at investigating whether, during a high-intensity 30-s unilateral maximal effort isometric leg extension exercise, the contralateral non-exercising limb (NEL) knee extensor muscle activation would differ between females and males. Methods Twenty participants, 11 females (23.80 ± 2.15 years old) and 9 males (26.50 ± 2.45 years old), performed a unilateral 30-s exercise while surface electromyography (sEMG) was measured from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) on both limbs. The maximal voluntary contraction (MVC) was measured for both the exercising limb (EL) and the NEL before (MVC PRE) and after (MVC POST) the 30-s exercise to assess muscle fatigue. Results While both females and males exhibited muscle fatigue in the EL (p = 0.015), females exhibited a lower MVC reduction than males (p = 0.042), suggesting that females were less fatigued than males. Although no muscle fatigue, i.e., no MVC force reduction was found in the NEL for either group before and after the 30-s exercise, the muscle activity of the VL was found to be of greater magnitude during the MVC POST only for females (p = 0.047) while it remained unchanged for males. During the 30-s exercise, the force output of the EL decreased only for males (p = 0.029) while females showed a preservation of the force output (p > 0.05). The sEMG activity of the NEL during the 30-s unilateral exercise increased for both groups in all measured muscles (all p-values < 0.03). Conclusions Likely, different underlying muscle fatigue mechanisms occurred in the EL between females and males. Yet, our findings suggest that the cross-over effect to the NEL during the 30-s exercise occurred in a similar fashion in both groups. The current study suggests that the contralateral muscle activation seen with a unilateral exercise is independent of the sex of individuals. Therefore, unilateral training or rehabilitation-based protocols would similarly impact females and males.
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Affiliation(s)
- Aude-Clémence M Doix
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria.
| | - Felix Wachholz
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Natalie Marterer
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Lorenz Immler
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Kathrin Insam
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Peter A Federolf
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
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The Test-Retest Reliability of New Generation Power Indices of Wingate All-Out Test. Sports (Basel) 2018; 6:sports6020031. [PMID: 29910335 PMCID: PMC6027544 DOI: 10.3390/sports6020031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 03/30/2018] [Accepted: 04/02/2018] [Indexed: 11/16/2022] Open
Abstract
Although reliability correlations of traditional power indices of the Wingate test have been well documented, no study has analyzed new generation power indices based on milliseconds obtained from a Peak Bike. The purpose of this study was to investigate the retest reliability of new generation power indices. Thirty-two well-trained male athletes who were specialized in basketball, football, tennis, or track and field volunteered to take part in the study (age: 24.3 ± 2.2 years; body mass: 77 ± 8.3 kg; height: 180.3 ± 6.3 cm). Participants performed two Wingate all-out sessions on two separate days. Intra-class correlation coefficient (ICC), standard error measurement (SEM), smallest real differences (SRD) and coefficient of variation (CV) scores were analyzed based on the test and retest data. Reliability results of traditional power indices calculated based on 5-s means such as peak power, average power, power drop, and fatigue index ratio were similar with the previous findings in literature (ICC ≥ 0.94; CV ≤ 2.8%; SEM ≤ 12.28; SRD% ≤ 7.7%). New generation power indices such as peak power, average power, lowest power, power drop, fatigue index, power decline, maximum speed as rpm, and amount of total energy expenditure demonstrated high reliability (ICC ≥ 0.94; CV ≤ 4.3%; SEM ≤ 10.36; SRD% ≤ 8.8%). Time to peak power, time at maximum speed, and power at maximum speed showed a moderate level of reliability (ICC ≥ 0.73; CV ≤ 8.9%; SEM ≤ 63.01; SRD% ≤ 22.4%). The results of this study indicate that reliability correlations and SRD% of new generation power and fatigue-related indices are similar with traditional 5-s means. However, new time-related indices are very sensitive and moderately reliable.
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Shi Q, Tong TK, Sun S, Kong Z, Chan CK, Liu W, Nie J. Influence of recovery duration during 6-s sprint interval exercise on time spent at high rates of oxygen uptake. J Exerc Sci Fit 2018; 16:16-20. [PMID: 30662487 PMCID: PMC6323236 DOI: 10.1016/j.jesf.2018.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 11/24/2017] [Accepted: 01/03/2018] [Indexed: 11/20/2022] Open
Abstract
Background/Objective This study examined whether time spent at high rates of oxygen consumption (VO2) during 6-s sprint interval exercises (SIE) is a function of recovery interval duration. Methods In a randomised crossover study, thirteen male endurance runners performed 40 × 6-s all-out sprints interspersed with 15-s, 30-s and 60-s passive recovery intervals (SIE15, SIE30, and SIE60 trials respectively), and a work duration-matched Wingate-SIE (8 × 30-s all-out sprints with 4-min passive recovery, SIEWin trial). The accumulated exercise time at ≥ 80%, 85%, 90%, 95% and 100% of VO2max, and maximum heart rate (HRmax) in the four trials were compared. Results During the 6-s SIEs, accumulated time spent at all selected high rates of VO2max increased as recovery time decreased, whilst the SIE work rate decreased (p < .05). In SIEWin, although the exercise lasted longer, the time spent at ≥90% VO2max (74 ± 16 s) was significant less than that in SIE15 (368 ± 63 s, p < .05), yet comparable to that in SIE30 (118 ± 30 s, p > .05), and longer than that in SIE60 (20 ± 14 s, p < .05). The differences between the four trials in accumulated time at high percentages of HRmax were similar to those for VO2, although the temporal characteristics of the increases in HR and VO2 during the SIEs were different. Conclusion In conclusion, the duration of the recovery interval in 6-s SIE protocols appears to be a crucial parameter when sprint interval training is prescribed to enhance aerobic capacity. Further, the SIE15 protocol may represent a potential alternative to 30-s SIEWin in the development of time-efficient aerobic training intervention.
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Affiliation(s)
- Qingde Shi
- School of Physical Education and Sports, Macao Polytechnic Institute, Macao, China
| | - Tomas K Tong
- Dr. Stephen Hui Research Centre for Physical Recreation and Wellness, Department of Physical Education, Hong Kong Baptist University, Hong Kong, China
| | - Shengyan Sun
- Faculty of Education, University of Macau, Macao, China.,Institute of Physical Education, Huzhou University, Huzhou, Zhejiang, China
| | - Zhaowei Kong
- Faculty of Education, University of Macau, Macao, China
| | - Chan Kit Chan
- School of Physical Education and Sports, Macao Polytechnic Institute, Macao, China
| | - Wei Liu
- Department of Cardiology, Beijing Hospital of the Ministry of Health, Beijing, China
| | - Jinlei Nie
- School of Physical Education and Sports, Macao Polytechnic Institute, Macao, China
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Beaudoin CM, Cox Z, Dundore T, Thomas T, Kim J, Pillivant D. Effect of Bench Press Load Knowledge on Repetitions, Rating of Perceived Exertion, and Attentional Focus. J Strength Cond Res 2017; 32:514-519. [PMID: 29140911 DOI: 10.1519/jsc.0000000000002331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Beaudoin, CM, Cox, Z, Dundore, T, Thomas, T, Kim, J, and Pillivant, D. Effect of bench press load knowledge on repetitions, rating of perceived exertion, and attentional focus. J Strength Cond Res 32(2): 514-519, 2018-Few studies have examined the role of the teleoanticipation during resistance training. The purpose of this study was to examine the effect of bench press (BP) load knowledge on repetitions completed, ratings of perceived exertion (RPEs), and attentional focus (% associative). Thirty-six recreationally active resistance-trained men (n = 25) and women (n = 11) participated in this study (age = 20.97 ± 1.87 years; ht = 174.12 ± 9.41 cm; and mass = 80.14 ± 14.03 kg). All subjects completed 3 testing sessions: (a) 1 repetition maximum (1RM) BP determination; (b) submaximal BP repetitions to fatigue known load (KL); and (c) submaximal BP repetitions to fatigue unknown load (UL). Known load and UL sessions were randomized and counterbalanced and both completed at 70% 1RM. An estimated weight ratio was computed using the subject's estimate of the UL weight relative to the KL weight. An independent samples t-test revealed no significant testing order difference for the estimated weight ratio. Two-way repeated-measures analysis of variances revealed no significant differences in the number of repetitions (p = 0.63), RPE (p = 0.18), or attentional focus (% associative) (p = 0.93) between the KL and UL conditions. Pearson correlations found a moderate positive association between KL repetitions completed and % associative focus when the UL was completed before the KL. Load knowledge did not influence the number of repetitions, RPE, or attentional focus while completing the BP. Further research examining the use of pacing strategies, RPE, and attentional focus during KL and UL conditions are warranted.
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Affiliation(s)
- Christina M Beaudoin
- Department of Movement Science, Grand Valley State University, Allendale, Michigan
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Girard O, Billaut F, Christian RJ, Bradley PS, Bishop DJ. Exercise-related sensations contribute to decrease power during repeated cycle sprints with limited influence on neural drive. Eur J Appl Physiol 2017; 117:2171-2179. [DOI: 10.1007/s00421-017-3705-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 08/22/2017] [Indexed: 01/30/2023]
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Shearman S, Dwyer D, Skiba P, Townsend N. Modeling Intermittent Cycling Performance in Hypoxia Using the Critical Power Concept. Med Sci Sports Exerc 2017; 48:527-35. [PMID: 26460632 DOI: 10.1249/mss.0000000000000794] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study investigated the efficacy of an intermittent critical power (CP) model, termed the "work-balance" (W'BAL) model, during high-intensity exercise in hypoxia (HYPO). METHODS Eleven trained male cyclists (mean ± SD age, 27 ± 6.6 yr; V˙O2peak, 4.79 ± 0.56 L·min(-1)) completed a maximal ramp test and a 3-min "all-out" test to determine CP and work performed above CP (W'). On another day, an intermittent exercise test to task failure was performed. All procedures were performed in normoxia (NORM) and HYPO (FiO2 ≈ 0.155) in a single-blind, randomized, and counter-balanced experimental design. The W'BAL model was used to calculate the minimum W' (W'BALmin) achieved during the intermittent test. The W'BALmin in HYPO was also calculated using CP + W' derived in NORM (N + H). RESULTS In HYPO, there was an 18% decrease in V˙O2peak (4.79 ± 0.56 vs 3.93 ± 0.47 L·min(-1); P < 0.001) and a 9% decrease in CP (347 ± 45 vs 316 ± 46 W; P < 0.001). No significant change for W' occurred (13.4 ± 3.9 vs 13.7 ± 4.9 kJ; P = 0.69; NORM vs HYPO). The change in V˙O2peak was significantly correlated with the change in CP (r = 0.72; P = 0.01). There was no difference between NORM and HYPO for W'BALmin (1.1 ± 0.9 kJ vs 1.2 ± 0.6 kJ). The N + H analysis grossly overestimated W'BALmin (7.8 ± 3.4 kJ) compared with HYPO (P < 0.001). CONCLUSION The W'BAL model produced similar results in HYPO and NORM, but only when model parameters were determined under the same environmental conditions as the performance task. Application of the W'BAL model at altitude requires a modification of the model or that CP and W' are measured at altitude.
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Affiliation(s)
- Samantha Shearman
- 1Centre for Exercise & Sport Science, Deakin University, Geelong, AUSTRALIA; 2Department of Sports Medicine, Advocate Lutheran General Hospital, Park Ridge, IL; and 3Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, QATAR
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Kavaliauskas M, Phillips SM. Reliability and sensitivity of the 6 and 30 second Wingate tests in physically active males and females. ISOKINET EXERC SCI 2016. [DOI: 10.3233/ies-160632] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Mykolas Kavaliauskas
- School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh, Scotland, UK
| | - Shaun M. Phillips
- Institute for Sport, Physical Education, and Health Sciences, University of Edinburgh, Edinburgh, Scotland, UK
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Saanijoki T, Nummenmaa L, Eskelinen JJ, Savolainen AM, Vahlberg T, Kalliokoski KK, Hannukainen JC. Affective Responses to Repeated Sessions of High-Intensity Interval Training. Med Sci Sports Exerc 2016; 47:2604-11. [PMID: 26110694 DOI: 10.1249/mss.0000000000000721] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Vigorous exercise feels unpleasant, and negative emotions may discourage adherence to regular exercise. We quantified the subjective affective responses to short-term high-intensity interval training (HIT) in comparison with moderate-intensity continuous training (MIT). METHODS Twenty-six healthy middle-age (mean age, 47 ± 5 yr; mean VO2peak, 34.2 ± 4.1 mL·kg⁻¹·min⁻¹) sedentary men were randomized into HIT (n = 13, 4-6 × 30 s of all-out cycling efforts at approximately 180% of peak workload with 4-min recovery) or MIT (n = 13, 40- to 60-min continuous cycling at 60% of peak workload) groups, performing six sessions within two weeks. Perceived exertion, stress, and affective state were recorded before, during, and after each session. RESULTS Perceived exertion and arousal were higher, and affective state, more negative during the HIT than that during MIT sessions (P < 0.001). HIT versus MIT exercise acutely increased the experience of stress, tension, and irritation and decreased positive affect (P < 0.05). In addition, satisfaction was lower and pain and negative affect were higher in the HIT than those in the MIT group (P < 0.05). However, perceived exertion and displeasure experienced during exercise alleviated similarly in response to HIT and MIT over the 6 d of training. Peak oxygen consumption increased (P < 0.001) after intervention (HIT, 34.7 ± 3.9 vs 36.7 ± 4.5; MIT, 33.9 ± 4.6 vs 35.0 ± 4.6) and was not different between HIT and MIT (P = 0.28 for group × training). CONCLUSIONS Short-term HIT and MIT are equally effective in improving aerobic fitness, but HIT increases experience of negative emotions and exertion in sedentary middle-age men. This may limit the adherence to this time-effective training mode, even though displeasure lessens over time and suggests similar mental adaptations to both MIT and HIT.
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Affiliation(s)
- Tiina Saanijoki
- 1Turku PET Centre, University of Turku and Turku University Hospital, Turku, FINLAND; 2Department of Biomedical Engineering and Computational Science and Brain Research Unit, O.V. Lounasmaa Laboratory, Aalto University, Espoo, FINLAND; and 3Department of Biostatistics, University of Turku, Turku, FINLAND
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The effect of high-intensity cycling training on postural sway during standing under rested and fatigued conditions in healthy young adults. Eur J Appl Physiol 2016; 116:1965-74. [PMID: 27491619 DOI: 10.1007/s00421-016-3448-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 07/28/2016] [Indexed: 01/25/2023]
Abstract
PURPOSE The purpose of this study was to investigate whether high-intensity cycling training leads to adapted responses of balance performance in response to exercise-induced muscle fatigue. METHODS Eighteen healthy adults were assigned to either 3-weeks (n = 8, age 20.1 ± 2.6 years, height 177 ± 5 cm, mass 73.6 ± 5.1 kg) or 6-weeks (n = 10, age 24.3 ± 5.8 years, height 179 ± 6 cm, mass 81.0 ± 15.8 kg) of high-intensity training (HIT) on a cycle ergometer. The centre of pressure (COP) displacement in the anteroposterior (COPAP) direction and COP path length (COPL) were measured before and after the first and final high-intensity training sessions. RESULTS Pre-training, exercise-induced fatigue elicited an increase in COPAP (3-weeks; p = 0.001, 6-weeks; p = 0.001) and COPL (3-weeks; p = 0.002, 6-weeks; p = 0.001) returning to pre-exercise levels within 10-min of recovery. Following 3-weeks of training, significant increases in COPAP (p = 0.001) and COPL (p = 0.002) were observed post-fatigue, returning to pre-exercise levels after 15-min of recovery. After 6-weeks of training no significant increases in sway (COPAP; p = 0.212, COPL; p = 0.998) were observed following exercise-induced fatigue. CONCLUSIONS In summary, 3 weeks of HIT resulted in longer recovery times following fatigue compared to pre-training assessments. After 6 weeks of HIT, postural sway following fatigue was attenuated. These results indicate that HIT could be included in injury prevention programmes, however, caution should be taken during early stages of the overreaching process.
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Girard O, Brocherie F, Tomazin K, Farooq A, Morin JB. Changes in running mechanics over 100-m, 200-m and 400-m treadmill sprints. J Biomech 2016; 49:1490-1497. [DOI: 10.1016/j.jbiomech.2016.03.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 02/12/2016] [Accepted: 03/13/2016] [Indexed: 11/26/2022]
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Higgins MF, Shabir A. Expectancy of ergogenicity from sodium bicarbonate ingestion increases high-intensity cycling capacity. Appl Physiol Nutr Metab 2016; 41:405-10. [DOI: 10.1139/apnm-2015-0523] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study examined whether expectancy of ergogenicity of a commonly used nutritional supplement (sodium bicarbonate; NaHCO3) influenced subsequent high-intensity cycling capacity. Eight recreationally active males (age, 21 ± 1 years; body mass, 75 ± 8 kg; height, 178 ± 4 cm; WPEAK = 205 ± 22 W) performed a graded incremental test to assess peak power output (WPEAK), one familiarisation trial and two experimental trials. Experimental trials consisted of cycling at 100% WPEAK to volitional exhaustion (TLIM) 60 min after ingesting either a placebo (PLA: 0.1 g·kg−1 sodium chloride (NaCl), 4 mL·kg−1 tap water, and 1 mL·kg−1 squash) or a sham placebo (SHAM: 0.1 g·kg−1 NaCl, 4 mL·kg−1 carbonated water, and 1 mL·kg−1 squash). SHAM aimed to replicate the previously reported symptoms of gut fullness (GF) and abdominal discomfort (AD) associated with NaHCO3 ingestion. Treatments were administered double blind and accompanied by written scripts designed to remain neutral (PLA) or induce expectancy of ergogenicity (SHAM). After SHAM mean TLIM increased by 9.5% compared to PLA (461 ± 148 s versus 421 ± 150 s; P = 0.048, d = 0.3). Ratings of GF and AD were mild but ∼1 unit higher post-ingestion for SHAM. After 3 min TLIM overall ratings of perceived exertion were 1.4 ± 1.3 units lower for SHAM compared to PLA (P = 0.020, d = 0.6). There were no differences between treatments for blood lactate, blood glucose, or heart rate. In summary, ergogenicity after NaHCO3 ingestion may be influenced by expectancy, which mediates perception of effort during subsequent exercise. The observed ergogenicity with SHAM did not affect our measures of cardiorespiratory physiology or metabolic flux.
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Affiliation(s)
- Matthew F. Higgins
- Sport, Outdoor and Exercise Science, Department of Life Sciences, Derby University, Kedleston Road, Derby, DE22 1GB, UK
- Sport, Outdoor and Exercise Science, Department of Life Sciences, Derby University, Kedleston Road, Derby, DE22 1GB, UK
| | - Akbar Shabir
- Sport, Outdoor and Exercise Science, Department of Life Sciences, Derby University, Kedleston Road, Derby, DE22 1GB, UK
- Sport, Outdoor and Exercise Science, Department of Life Sciences, Derby University, Kedleston Road, Derby, DE22 1GB, UK
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Higgins MF, Wilson S, Hill C, Price MJ, Duncan M, Tallis J. Evaluating the effects of caffeine and sodium bicarbonate, ingested individually or in combination, and a taste-matched placebo on high-intensity cycling capacity in healthy males. Appl Physiol Nutr Metab 2016; 41:354-61. [PMID: 26988768 DOI: 10.1139/apnm-2015-0371] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study evaluated the effects of ingesting sodium bicarbonate (NaHCO3) or caffeine individually or in combination on high-intensity cycling capacity. In a counterbalanced, crossover design, 13 healthy, noncycling trained males (age: 21 ± 3 years, height: 178 ± 6 cm, body mass: 76 ± 12 kg, peak power output (Wpeak): 230 ± 34 W, peak oxygen uptake: 46 ± 8 mL·kg(-1)·min(-1)) performed a graded incremental exercise test, 2 familiarisation trials, and 4 experimental trials. Trials consisted of cycling to volitional exhaustion at 100% Wpeak (TLIM) 60 min after ingesting a solution containing either (i) 0.3 g·kg(-1) body mass sodium bicarbonate (BIC), (ii) 5 mg·kg(-1) body mass caffeine plus 0.1 g·kg(-1) body mass sodium chloride (CAF), (iii) 0.3 g·kg(-1) body mass sodium bicarbonate plus 5 mg·kg(-1) body mass caffeine (BIC-CAF), or (iv) 0.1 g·kg(-1) body mass sodium chloride (PLA). Experimental solutions were administered double-blind. Pre-exercise, at the end of exercise, and 5-min postexercise blood pH, base excess, and bicarbonate ion concentration ([HCO3(-)]) were significantly elevated for BIC and BIC-CAF compared with CAF and PLA. TLIM (median; interquartile range) was significantly greater for CAF (399; 350-415 s; P = 0.039; r = 0.6) and BIC-CAF (367; 333-402 s; P = 0.028; r = 0.6) compared with BIC (313: 284-448 s) although not compared with PLA (358; 290-433 s; P = 0.249, r = 0.3 and P = 0.099 and r = 0.5, respectively). There were no differences between PLA and BIC (P = 0.196; r = 0.4) or between CAF and BIC-CAF (P = 0.753; r = 0.1). Relatively large inter- and intra-individual variation was observed when comparing treatments and therefore an individual approach to supplementation appears warranted.
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Affiliation(s)
- Matthew F Higgins
- a Department of Life Sciences, Sport, Outdoor and Exercise Science, Derby University, Kedleston Road, Derby DE22 1GB, UK
| | - Susie Wilson
- b Department of Applied Sciences and Health, Coventry University, James Starley Building, Cox Street, Coventry CV1 5FB, UK
| | - Cameron Hill
- b Department of Applied Sciences and Health, Coventry University, James Starley Building, Cox Street, Coventry CV1 5FB, UK
| | - Mike J Price
- b Department of Applied Sciences and Health, Coventry University, James Starley Building, Cox Street, Coventry CV1 5FB, UK
| | - Mike Duncan
- b Department of Applied Sciences and Health, Coventry University, James Starley Building, Cox Street, Coventry CV1 5FB, UK
| | - Jason Tallis
- b Department of Applied Sciences and Health, Coventry University, James Starley Building, Cox Street, Coventry CV1 5FB, UK
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Bigliassi M, Silva VB, Karageorghis CI, Bird JM, Santos PC, Altimari LR. Brain mechanisms that underlie the effects of motivational audiovisual stimuli on psychophysiological responses during exercise. Physiol Behav 2016; 158:128-36. [PMID: 26948160 DOI: 10.1016/j.physbeh.2016.03.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/01/2016] [Accepted: 03/02/2016] [Indexed: 01/19/2023]
Abstract
Motivational audiovisual stimuli such as music and video have been widely used in the realm of exercise and sport as a means by which to increase situational motivation and enhance performance. The present study addressed the mechanisms that underlie the effects of motivational stimuli on psychophysiological responses and exercise performance. Twenty-two participants completed fatiguing isometric handgrip-squeezing tasks under two experimental conditions (motivational audiovisual condition and neutral audiovisual condition) and a control condition. Electrical activity in the brain and working muscles was analyzed by use of electroencephalography and electromyography, respectively. Participants were asked to squeeze the dynamometer maximally for 30s. A single-item motivation scale was administered after each squeeze. Results indicated that task performance and situational motivational were superior under the influence of motivational stimuli when compared to the other two conditions (~20% and ~25%, respectively). The motivational stimulus downregulated the predominance of low-frequency waves (theta) in the right frontal regions of the cortex (F8), and upregulated high-frequency waves (beta) in the central areas (C3 and C4). It is suggested that motivational sensory cues serve to readjust electrical activity in the brain; a mechanism by which the detrimental effects of fatigue on the efferent control of working muscles is ameliorated.
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Affiliation(s)
| | - Vinícius B Silva
- Department of Physical Education, Londrina State University, Brazil
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HUREAU THOMASJ, DUCROCQ GUILLAUMEP, BLAIN GREGORYM. Peripheral and Central Fatigue Development during All-Out Repeated Cycling Sprints. Med Sci Sports Exerc 2016; 48:391-401. [DOI: 10.1249/mss.0000000000000800] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wright RL. Positive Pacing Strategies Are Utilized by Elite Male and Female Para-cyclists in Short Time Trials in the Velodrome. Front Physiol 2016; 6:425. [PMID: 26834643 PMCID: PMC4716664 DOI: 10.3389/fphys.2015.00425] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 12/24/2015] [Indexed: 11/22/2022] Open
Abstract
In para-cycling, competitors are classed based on functional impairment resulting in cyclists with neurological and locomotor impairments competing against each other. In Paralympic competition, classes are combined by using a factoring adjustment to race times to produce the overall medallists. Pacing in short-duration track cycling events is proposed to utilize an “all-out” strategy in able-bodied competition. However, pacing in para-cycling may vary depending on the level of impairment. Analysis of the pacing strategies employed by different classification groups may offer scope for optimal performance; therefore, this study investigated the pacing strategy adopted during the 1-km time trial (TT) and 500-m TT in elite C1 to C3 para-cyclists and able-bodied cyclists. Total times and intermediate split times (125-m intervals; measured to 0.001 s) were obtained from the C1-C3 men's 1-km TT (n = 28) and women's 500-m TT (n = 9) from the 2012 Paralympic Games and the men's 1-km TT (n = 19) and women's 500-m TT (n = 12) from the 2013 UCI World Track Championships from publically available video. Split times were expressed as actual time, factored time (for the para-cyclists) and as a percentage of total time. A two-way analysis of variance was used to investigate differences in split times between the different classifications and the able-bodied cyclists in the men's 1-km TT and between the para-cyclists and able-bodied cyclists in the women's 500-m TT. The importance of position at the first split was investigated with Kendall's Tau-b correlation. The first 125-m split time was the slowest for all cyclists, representing the acceleration phase from a standing start. C2 cyclists were slowest at this 125-m split, probably due to a combination of remaining seated in this acceleration phase and a high proportion of cyclists in this group being trans-femoral amputees. Not all cyclists used aero-bars, preferring to use drop, flat or bullhorn handlebars. Split times increased in the later stages of the race, demonstrating a positive pacing strategy. In the shorter women's 500-m TT, rank at the first split was more strongly correlated with final position than in the longer men's 1-km TT. In conclusion, a positive pacing strategy was adopted by the different para-cycling classes.
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Affiliation(s)
- Rachel L Wright
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham Birmingham, UK
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Bigliassi M. Use the brain: complementary methods to analyse the effects of motivational music. Front Hum Neurosci 2015; 9:508. [PMID: 26441605 PMCID: PMC4584946 DOI: 10.3389/fnhum.2015.00508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 08/31/2015] [Indexed: 01/24/2023] Open
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Bigliassi M. Corollary discharges and fatigue-related symptoms: the role of attentional focus. Front Psychol 2015; 6:1002. [PMID: 26236271 PMCID: PMC4500863 DOI: 10.3389/fpsyg.2015.01002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 07/02/2015] [Indexed: 11/16/2022] Open
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Christian RJ, Bishop DJ, Billaut F, Girard O. Peripheral fatigue is not critically regulated during maximal, intermittent, dynamic leg extensions. J Appl Physiol (1985) 2014; 117:1063-73. [PMID: 25213635 DOI: 10.1152/japplphysiol.00988.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Central motor drive to active muscles is believed to be reduced during numerous exercise tasks to prevent excessive peripheral fatigue development. The purpose of the present study was to use hypoxia to exacerbate physiological perturbations during a novel, intermittent exercise task and to explore the time-course and interplay between central and peripheral neuromuscular adjustments. On separate days, 14 healthy men performed four sets of 6 × 5 maximal-intensity, isokinetic leg extensions (1 repetition lasting ∼7 s) at 300°/s (15 and 100 s of passive rest between repetitions and sets, respectively) under normoxia (NM, fraction of inspired O2 0.21), moderate (MH, 0.14), and severe normobaric hypoxia (SH, 0.10). Neuromuscular assessments of the knee extensors were conducted before and immediately after each set. There was an interaction between time and condition on the mean peak torque produced during each set (P < 0.05). RMS/M-wave activity of the rectus femoris decreased across the four sets of exercise, but there was no difference between conditions (8.3 ± 5.1% all conditions compounded, P > 0.05). Potentiated twitch torque decreased post set 1 in all conditions (all P < 0.05) with greater reductions following each set in SH compared with NM but not MH (end-exercise reductions 41.3 ± 3.0% vs. 28.0 ± 3.2%, P < 0.05 and 32.1 ± 3.3%, P > 0.05). In conclusion, severe hypoxia exacerbates both peripheral fatigue development and performance decrements during maximal, intermittent, dynamic leg extensions. In contrast to observations with other exercise modes, during exercise involving a single muscle group the attenuation of central motor drive does not appear to independently regulate the development of peripheral muscle fatigue.
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Affiliation(s)
- Ryan J Christian
- College of Sport and Exercise Science, Victoria University, Melbourne, Australia; Aspetar - Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar;
| | - David J Bishop
- Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia
| | - François Billaut
- Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia; Université Laval, Département de Kinésiologie, Québec, Québec, Canada; and
| | - Olivier Girard
- Aspetar - Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar; Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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Silva RA, Silva-Júnior FL, Pinheiro FA, Souza PF, Boullosa DA, Pires FO. Acute Prior Heavy Strength Exercise Bouts Improve the 20-km Cycling Time Trial Performance. J Strength Cond Res 2014; 28:2513-20. [DOI: 10.1519/jsc.0000000000000442] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Hureau TJ, Olivier N, Millet GY, Meste O, Blain GM. Exercise performance is regulated during repeated sprints to limit the development of peripheral fatigue beyond a critical threshold. Exp Physiol 2014; 99:951-63. [PMID: 24728680 DOI: 10.1113/expphysiol.2014.077974] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We hypothesized that exercise performance is adjusted during repeated sprints in order not to surpass a critical threshold of peripheral fatigue. Twelve men randomly performed three experimental sessions on different days, i.e. one single 10 s all-out sprint and two trials of 10 × 10 s all-out sprints with 30 s of passive recovery in between. One trial was performed in the unfatigued state (CTRL) and one following electrically induced quadriceps muscle fatigue (FTNMES). Peripheral fatigue was quantified by comparing pre- with postexercise changes in potentiated quadriceps twitch force (ΔQtw-pot) evoked by supramaximal magnetic stimulation of the femoral nerve. Central fatigue was estimated by comparing pre- with postexercise voluntary activation of quadriceps motor units. The root mean square (RMS) of the vastus lateralis and vastus medialis EMG normalized to maximal M-wave amplitude (RMS.Mmax (-1)) was also calculated during sprints. Compared with CTRL condition, pre-existing quadriceps muscle fatigue in FTNMES (ΔQtw-pot = -29 ± 4%) resulted in a significant (P < 0.05) reduction in power output (-4.0 ± 0.9%) associated with a reduction in RMS.Mmax (-1). However, ΔQtw-pot postsprints decreased by 51% in both conditions, indicating that the level of peripheral fatigue was identical and independent of the degree of pre-existing fatigue. Our findings show that power output and cycling EMG are adjusted during exercise in order to limit the development of peripheral fatigue beyond a constant threshold. We hypothesize that the contribution of peripheral fatigue to exercise limitation involves a reduction in central motor drive in addition to the impairment in muscular function.
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Affiliation(s)
- Thomas J Hureau
- University of Nice Sophia Antipolis, Toulon, LAMHESS, EA 6309, F-06205, Nice, France University of Lille Nord de France, F-59000, Lille, France; UDSL, EA 4488, F-59790, Ronchin, France
| | - Nicolas Olivier
- University of Lille Nord de France, F-59000, Lille, France; UDSL, EA 4488, F-59790, Ronchin, France
| | - Guillaume Y Millet
- University of Lyon, F-42023, Saint Etienne, France University of Calgary, Faculty of Kinesiology, Human Performance Laboratory, Calgary, Alberta, Canada
| | - Olivier Meste
- CNRS - University of Nice Sophia Antipolis, I3S, F-06900, Sophia Antipolis, France
| | - Gregory M Blain
- University of Nice Sophia Antipolis, Toulon, LAMHESS, EA 6309, F-06205, Nice, France University of Lille Nord de France, F-59000, Lille, France; UDSL, EA 4488, F-59790, Ronchin, France
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Christian RJ, Bishop DJ, Billaut F, Girard O. The role of sense of effort on self-selected cycling power output. Front Physiol 2014; 5:115. [PMID: 24744734 PMCID: PMC3978313 DOI: 10.3389/fphys.2014.00115] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 03/08/2014] [Indexed: 01/09/2023] Open
Abstract
PURPOSE We explored the effects of the sense of effort and accompanying perceptions of peripheral discomfort on self-selected cycle power output under two different inspired O2 fractions. METHODS On separate days, eight trained males cycled for 5 min at a constant subjective effort (sense of effort of '3' on a modified Borg CR10 scale), immediately followed by five 4-s progressive submaximal (sense of effort of "4, 5, 6, 7, and 8"; 40 s between bouts) and two 4-s maximal (sense of effort of "10"; 3 min between bouts) bouts under normoxia (NM: fraction of inspired O2 [FiO2] 0.21) and hypoxia (HY: [FiO2] 0.13). Physiological (Heart Rate, arterial oxygen saturation (SpO2) and quadriceps Root Mean Square (RMS) electromyographical activity) and perceptual responses (overall peripheral discomfort, difficulty breathing and limb discomfort) were recorded. RESULTS Power output and normalized quadriceps RMS activity were not different between conditions during any exercise bout (p > 0.05) and remained unchanged across time during the constant-effort cycling. SpO2 was lower, while heart rate and ratings of perceived difficulty breathing were higher under HY, compared to NM, at all time points (p < 0.05). During the constant-effort cycling, heart rate, overall perceived discomfort, difficulty breathing and limb discomfort increased with time (all p < 0.05). All variables (except SpO2) increased along with sense of effort during the brief progressive cycling bouts (all p < 0.05). During the two maximal cycling bouts, ratings of overall peripheral discomfort displayed an interaction between time and condition with ratings higher in the second bout under HY vs. NM conditions. CONCLUSION During self-selected, constant-effort and brief progressive, sub-maximal, and maximal cycling bouts, mechanical work is regulated in parallel to the sense of effort, independently from peripheral sensations of discomfort.
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Affiliation(s)
- Ryan J. Christian
- Institute of Sport, Exercise and Active Living, College of Sport and Exercise Science, Victoria UniversityMelbourne, VIC, Australia
- Aspetar - Athlete Health and Performance Research Centre, Qatar Orthopaedic and Sports Medicine HospitalDoha, Qatar
| | - David J. Bishop
- Institute of Sport, Exercise and Active Living, College of Sport and Exercise Science, Victoria UniversityMelbourne, VIC, Australia
| | - François Billaut
- Institute of Sport, Exercise and Active Living, College of Sport and Exercise Science, Victoria UniversityMelbourne, VIC, Australia
- Départment de Kinésiology, Université LavalQuébec, QC, Canada
| | - Olivier Girard
- Aspetar - Athlete Health and Performance Research Centre, Qatar Orthopaedic and Sports Medicine HospitalDoha, Qatar
- Faculty of Biology and Medicine, Institute of Sport Sciences, University of LausanneLausanne, Switzerland
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Halperin I, Aboodarda SJ, Basset FA, Byrne JM, Behm DG. Pacing strategies during repeated maximal voluntary contractions. Eur J Appl Physiol 2014; 114:1413-20. [PMID: 24658878 DOI: 10.1007/s00421-014-2872-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 03/05/2014] [Indexed: 10/25/2022]
Abstract
PURPOSE Pacing strategies have been reported to occur during continuous cyclical exercises. However, currently no studies have examined if pacing takes place during repeated maximal voluntary muscle contractions (MVCs). Accordingly, the purpose of this study was to examine if informing subjects on the number of MVCs they would perform would affect force and root mean squared electromyography (EMG), during similar fatiguing protocols. METHODS Thirty well-trained male subjects completed three fatiguing protocols in a randomized order. In the control condition participants were informed they would perform 12 MVCs, and then completed all 12. In the unknown condition they were not told how many MVCs they would perform, but were stopped after 12. Lastly, in the deception condition they were initially told they would perform only 6 MVCs, but after the 6 contractions they were asked to perform a few more repetitions and were stopped after 12. RESULTS Compared to the unknown condition, subjects demonstrated greater forces (p < 0.05, ES = 0.35-1.14, 2-7.5%) and biceps EMG (p < 0.05, ES = 0.6, 6%) in the deception condition during the first six MVCs. Additionally, under all conditions subjects applied greater forces in the last repetition (#12) relative to the previous one (#11) (p < 0.06, ES = 0.36-0.5, 2.8-3.8%). CONCLUSIONS The anticipation of performing a certain number of MVCs led the subjects to utilize different pacing strategies. The results also question the assumption that subjects followed the instruction to exert maximal effort during repeated MVCs.
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Affiliation(s)
- I Halperin
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada
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Interaction of central and peripheral factors during repeated sprints at different levels of arterial O2 saturation. PLoS One 2013; 8:e77297. [PMID: 24155938 PMCID: PMC3796493 DOI: 10.1371/journal.pone.0077297] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/31/2013] [Indexed: 11/19/2022] Open
Abstract
Purpose To investigate the interaction between the development of peripheral locomotor muscle fatigue, muscle recruitment and performance during repeated-sprint exercise (RSE). Method In a single-blind, randomised and cross-over design, ten male team-sport athletes performed two RSE (fifteen 5-s cycling sprints interspersed with 25 s of rest; power self-selected) in normoxia and in acute moderate hypoxia (FIO2 0.138). Mechanical work, total electromyographic intensity (summed quadriceps electromyograms, RMSsum) and muscle (vastus lateralis) and pre-fontal cortex near-infrared spectroscopy (NIRS) parameters were calculated for every sprint. Blood lactate concentration ([Lac-]) was measured throughout the protocol. Peripheral quadriceps fatigue was assessed via changes in potentiated quadriceps twitch force (ΔQtw,pot) pre- versus post-exercise in response to supra-maximal magnetic femoral nerve stimulation. The central activation ratio (QCAR) was used to quantify completeness of quadriceps activation. Results Compared with normoxia, hypoxia reduced arterial oxygen saturation (-13.7%, P=0.001), quadriceps RMSsum (-13.7%, P=0.022), QCAR (-3.3%, P=0.041) and total mechanical work (-8.3%, P=0.019). However, the magnitude of quadriceps fatigue induced by RSE was similar in the two conditions (ΔQtw,pot: -53.5% and -55.1%, P=0.71). The lower cycling performance in hypoxia occurred despite similar metabolic (muscle NIRS parameters and blood [Lac-]) and functional (twitch and M-wave) muscle states. Conclusion Results suggest that the central nervous system regulates quadriceps muscle recruitment and, thereby, performance to limit the development of muscle fatigue during intermittent, short sprints. This finding highlights the complex interaction between muscular perturbations and neural adjustments during sprint exercise, and further supports the presence of pacing during intermittent sprint exercise.
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Bieuzen F, Borne R, Toussaint JF, Hausswirth C. Positive effect of specific low-frequency electrical stimulation during short-term recovery on subsequent high-intensity exercise. Appl Physiol Nutr Metab 2013; 39:202-10. [PMID: 24476476 DOI: 10.1139/apnm-2013-0185] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to test how low-frequency electrical stimulation (LFES; Veinoplus Sport (AdRem Technology, Paris, France)) of the calf muscles affects recovery indices compared with 2 other commonly used recovery methods (active, ACT; passive, PAS). The tests used assessed predominantly anaerobic performance after short-term (15 min) recovery, and the kinetics of blood markers. Fourteen highly trained female handball players completed 2 Yo-Yo Intermittent Recovery tests (level 2; YYIR2) separated by a 15-min recovery period. During recovery, 1 of 3 recovery methods (ACT, LFES or PAS) was randomly selected. Performance (i.e., distance run) was measured at the end of each YYIR2 test. Blood lactate, pH, bicarbonate concentrations, heart rate, respiratory gas exchange and tissue saturation index for the lateral gastrocnemius were recorded. LFES showed a very likely beneficial effect on performance during the second YYIR2 relative to PAS and a possible beneficial effect relative to ACT (distance Pre vs. Post; LFES: -1.8%; ACT: -7.6%; PAS: -15.9%). Compared with PAS recovery, LFES and ACT recovery clearly showed a faster return to baseline for blood lactate, pH and bicarbonate concentrations during the recovery period. LFES of the calf muscles and, to a lesser extent, ACT recovery appear to effectively improve short-term recovery between 2 bouts of exhausting exercises. These methods could be of benefit if applied during half-time, for sports involving successive rounds, or where only a limited recovery period is available.
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Affiliation(s)
- François Bieuzen
- Laboratory of Sport, Expertise and Performance, French Institute of Sport, Expertise and Performance (INSEP), 11 ave. du Tremblay, 75012 Paris, France
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Time course of the cross-over effect of fatigue on the contralateral muscle after unilateral exercise. PLoS One 2013; 8:e64910. [PMID: 23741417 PMCID: PMC3669025 DOI: 10.1371/journal.pone.0064910] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/19/2013] [Indexed: 11/19/2022] Open
Abstract
We investigated the cross-over effect of muscle fatigue and its time course on the non-exercising contralateral limb (NEL) after unilateral fatiguing contractions of the ipsilateral exercising limb (EL). For this purpose, 15 males performed two bouts of 100-second maximal isometric knee extensions with the exercising limb, and neuromuscular function of both the EL and NEL was assessed before (PRE), after a first fatiguing exercise (MID) and after a second fatiguing exercise (POST). Maximal voluntary isometric torque production declined in the EL after the first bout of exercise (-9.6%; p<0.001) while in the NEL, the decrease occurred after the second bout of exercise (-10.6%; p<0.001). At MID, torque decline of the EL was strictly associated to an alteration of the mechanical twitch properties evoked by neurostimulation of the femoral nerve (i.e., peak twitch torque, maximal rate of twitch development). According to these markers, we suggest that peripheral fatigue occurred. At POST, after the second bout of exercise, the voluntary activation level of the knee extensor muscles was altered from PRE (-9.1%; p<0.001), indicating an overall central failure in both the EL and NEL. These findings indicate that two bouts of unilateral fatiguing exercise were needed to induce a cross-over effect of muscle fatigue on the non-exercising contralateral limb. Differential adjustments of the motor pathway (peripheral fatigue vs. central fatigue) might contribute to the respective torque decline in the EL and the NEL. Given that our unilateral fatiguing exercise induced immediate maximal torque reduction in the EL and postponed the loss of torque production in the NEL, it is also concluded that the time course of muscle fatigue differed between limbs.
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Higgins MF, James RS, Price MJ. The effects of sodium bicarbonate (NaHCO3) ingestion on high intensity cycling capacity. J Sports Sci 2013; 31:972-81. [DOI: 10.1080/02640414.2012.758868] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Noakes TD. Fatigue is a Brain-Derived Emotion that Regulates the Exercise Behavior to Ensure the Protection of Whole Body Homeostasis. Front Physiol 2012; 3:82. [PMID: 22514538 PMCID: PMC3323922 DOI: 10.3389/fphys.2012.00082] [Citation(s) in RCA: 222] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 03/20/2012] [Indexed: 11/18/2022] Open
Abstract
An influential book written by A. Mosso in the late nineteenth century proposed that fatigue that “at first sight might appear an imperfection of our body, is on the contrary one of its most marvelous perfections. The fatigue increasing more rapidly than the amount of work done saves us from the injury which lesser sensibility would involve for the organism” so that “muscular fatigue also is at bottom an exhaustion of the nervous system.” It has taken more than a century to confirm Mosso’s idea that both the brain and the muscles alter their function during exercise and that fatigue is predominantly an emotion, part of a complex regulation, the goal of which is to protect the body from harm. Mosso’s ideas were supplanted in the English literature by those of A. V. Hill who believed that fatigue was the result of biochemical changes in the exercising limb muscles – “peripheral fatigue” – to which the central nervous system makes no contribution. The past decade has witnessed the growing realization that this brainless model cannot explain exercise performance. This article traces the evolution of our modern understanding of how the CNS regulates exercise specifically to insure that each exercise bout terminates whilst homeostasis is retained in all bodily systems. The brain uses the symptoms of fatigue as key regulators to insure that the exercise is completed before harm develops. These sensations of fatigue are unique to each individual and are illusionary since their generation is largely independent of the real biological state of the athlete at the time they develop. The model predicts that attempts to understand fatigue and to explain superior human athletic performance purely on the basis of the body’s known physiological and metabolic responses to exercise must fail since subconscious and conscious mental decisions made by winners and losers, in both training and competition, are the ultimate determinants of both fatigue and athletic performance.
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Affiliation(s)
- Timothy David Noakes
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town Cape Town, South Africa
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de Ruiter CJ, Maas EA, Wesseling MGH, de Haan A. Knee extensor fatigue threshold is related to whole-body VO2max. Med Sci Sports Exerc 2012; 44:1366-74. [PMID: 22246220 DOI: 10.1249/mss.0b013e318249d701] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Above a given exercise intensity, rapid muscle fatigue will occur. We explored the possibility of assessing torque threshold for peripheral fatigue during single-legged repetitive isometric knee extensor exercise. We hypothesized this fatigue threshold to be related to the general aerobic fitness level and the so-called "critical torque" (CT) established with a recently validated 5-min all-out test. METHODS Seventeen healthy men (VO(2max) = 44.7-69.6 mL·kg(-1)·min(-1)) performed six submaximal (20%-55% maximal voluntary contraction [MVC]) 5-min bouts of 60 repetitive contractions (3-s on, 2-s off). Torque was changed between bouts in steps of 5% MVC to estimate the highest intensity (fatigue threshold) at which average changes in rsEMG, EMG median power frequency, and tissue deoxygenation (near-infrared spectroscopy) of the three superficial knee extensor muscles were still <5%, signifying steady-state exercise with minimal peripheral fatigue. On another occasion, one bout was performed in an all-out manner with end-test torque representing CT. RESULTS Fatigue threshold (40.0% ± 8.1% MVC) was related (r(2) = 0.57, P < 0.05) to CT (53.1% ± 10.0% MVC), but it was consistently lower (P < 0.05) and only fatigue threshold was significantly related to VO(2max) (r(2) = 0.68), and the first (r(2) = 0.45) and second (r(2) = 0.63) ventilatory threshold obtained during cycle ergometry. CONCLUSIONS Performing submaximal bouts of knee extensor contractions, while monitoring EMG and deoxygenation, seems a feasible manner to estimate an aerobic capacity-related exercise intensity of peripheral fatigue onset. This test may be used to evaluate changes in endurance capacity of single muscle groups, without the necessity for all-out testing, which could be problematic with frail subjects.
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Noakes TD. Is it time to retire the A.V. Hill Model?: A rebuttal to the article by Professor Roy Shephard. Sports Med 2011; 41:263-77. [PMID: 21425886 DOI: 10.2165/11583950-000000000-00000] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recent publications by Emeritus Professor Roy Shephard propose that a "small group of investigators who have argued repeatedly (over the past 13 years) for a 'Central Governor'," should now either "Put up or shut up." Failing this, their 'hypothesis' should be 'consigned to the bottom draw for future reference'; but Professor Shephard's arguments are contradictory. Thus, in different sections of his article, Professor Shephard explains: why there is no need for a brain to regulate exercise performance; why there is no proof that the brain regulates exercise performance; and why the brain's proven role in the regulation of exercise performance is already so well established that additional comment and research is unnecessary. Hence, "The higher centres of an endurance athlete … call forth an initial effort … at a level where a minimal accumulation of lactate in the peripheral muscles is sensed." Furthermore, "a variety of standard texts have illustrated the many mutually redundant feedback loops (to the nervous system) that limit exercise." Yet, the figure from Professor Shephard's 1982 textbook does not contain any links between the nervous system, "many mutually redundant feedback loops" and skeletal muscle. This disproves his contradictory claims that although there is neither any need for, nor any proof of, any role of the brain in the regulation of exercise performance, the physiological mechanisms for this (non-existent) control were already well established in 1982. In contrast, the Central Governor Model (CGM) developed by our "small group … in a single laboratory" after 1998, provides a simple and unique explanation of how 'redundant feedback loops' can assist in the regulation of exercise behaviour. In this rebuttal to his article, I identify (i) the numerous contradictions included in Professor Shephard's argument; (ii) the real meaning of the facts that he presents; (iii) the importance of the evidence that he ignores; and (iv) the different philosophies of how science should be conducted according to either the Kuhnian or the Popperian philosophies of scientific discovery. My conclusion is that the dominance of an authoritarian Kuhnian philosophy, which refuses to admit genuine error or "the need to alter one's course of belief or action," explains why there is little appetite in the exercise sciences for the acceptance of genuinely novel ideas such as the CGM. Furthermore, to advance the case for the CGM, I now include evidence from more than 30 studies, which, in my opinion, can only be interpreted according to a model of exercise regulation where the CNS, acting in an anticipatory manner, regulates the exercise behaviour by altering skeletal muscle recruitment, specifically to ensure that homeostasis is maintained during exercise. Since few, if any, of those studies can be explained by the 'brainless' A.V. Hill Cardiovascular Model on which Professor Shephard bases his arguments, I argue that it is now the appropriate time to retire that model. Perhaps this will bring to an end the charade that holds either (i) that the brain plays no part in the regulation of exercise performance; or, conversely, (ii) that the role of the brain is already so well defined that further research by other scientists is unnecessary. However, this cannot occur in a discipline that is dominated by an authoritarian Kuhnian philosophy.
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Affiliation(s)
- Timothy D Noakes
- Discovery Health Chair of Exercise and Sports Science, UCT/MRC Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Cape Town, South Africa.
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Skein M, Duffield R, Cannon J, Marino FE. Self-paced intermittent-sprint performance and pacing strategies following respective pre-cooling and heating. Eur J Appl Physiol 2011; 112:253-66. [PMID: 21537928 DOI: 10.1007/s00421-011-1972-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 04/15/2011] [Indexed: 11/28/2022]
Abstract
This study examined the effects of pre-exercise cooling and heating on neuromuscular function, pacing and intermittent-sprint performance in the heat. Ten male, team sport athletes completed three randomized, counterbalanced conditions including a thermo-neutral environment (CONT), whole body submersion in an ice bath (ICE) and passive heating in a hot environment (HEAT) before 50 min of intermittent-sprint exercise (ISE) in the heat (31 + 1°C). Exercise involved repeated 15 m maximal sprints and self-paced exercise of varying intensities. Performance was measured by sprint times and distance covered during self-paced exercise. Maximal isometric contractions were performed to determine the maximal voluntary torque (MVT), activation (VA) and contractile properties. Physiological measures included heart rate (HR), core (T (core)) and skin (T (skin)) temperatures, capillary blood and perceptual ratings. Mean sprint times were slower during ICE compared to HEAT (P < 0.05). Total distance covered was not different between conditions, but less distance was covered during HEAT in 31-40 min compared to CONT, and 41-50 min compared to ICE (P < 0.05). MVT was reduced post-exercise compared to post-intervention in CONT and HEAT. VA was reduced post-intervention in HEAT compared to CONT and ICE, and post-exercise compared to ICE (P < 0.05). HR, T (core) and T (skin) during exercise were lower in ICE compared to CONT and HEAT (P < 0.05). Sprint times and distance covered were not affected by ICE and HEAT conditions compared to CONT. However, initial sprint performance was slowed by pre-cooling, with improvements following passive heating possibly due to altered contractile properties. Conversely, pre-cooling improved exercise intensities, whilst HEAT resulted in greater declines in muscle recruitment and ensuing distance covered.
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BILLAUT FRANÇOIS, BISHOP DAVIDJ, SCHAERZ SIMON, NOAKES TIMOTHYD. Influence of Knowledge of Sprint Number on Pacing during Repeated-Sprint Exercise. Med Sci Sports Exerc 2011; 43:665-72. [DOI: 10.1249/mss.0b013e3181f6ee3b] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Noakes TD. Time to move beyond a brainless exercise physiology: the evidence for complex regulation of human exercise performance. Appl Physiol Nutr Metab 2011; 36:23-35. [DOI: 10.1139/h10-082] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In 1923, Nobel Laureate A.V. Hill proposed that maximal exercise performance is limited by the development of anaerobiosis in the exercising skeletal muscles. Variants of this theory have dominated teaching in the exercise sciences ever since, but 90 years later there is little biological evidence to support Hill’s belief, and much that disproves it. The cardinal weakness of the Hill model is that it allows no role for the brain in the regulation of exercise performance. As a result, it is unable to explain at least 6 common phenomena, including (i) differential pacing strategies for different exercise durations; (ii) the end spurt; (iii) the presence of fatigue even though homeostasis is maintained; (iv) fewer than 100% of the muscle fibers have been recruited in the exercising limbs; (v) the evidence that a range of interventions that act exclusively on the brain can modify exercise performance; and (vi) the finding that the rating of perceived exertion is a function of the relative exercise duration rather than the exercise intensity. Here I argue that the central governor model (CGM) is better able to explain these phenomena. In the CGM, exercise is seen as a behaviour that is regulated by complex systems in the central nervous system specifically to ensure that exercise terminates before there is a catastrophic biological failure. The complexity of this regulation cannot be appreciated if the body is studied as a collection of disconnected components, as is the usual approach in the modern exercise sciences.
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Affiliation(s)
- Timothy David Noakes
- UCT–MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town and Sports Science Institute of South Africa, Boundary Road, Newlands, 7700, South Africa (e-mail: )
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Lactate response to short term exercise with elevated starting levels. Eur J Appl Physiol 2010; 110:215-8. [DOI: 10.1007/s00421-010-1481-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2010] [Indexed: 10/19/2022]
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The limit to exercise tolerance in humans: mind over muscle? Eur J Appl Physiol 2010; 109:763-70. [PMID: 20221773 DOI: 10.1007/s00421-010-1418-6] [Citation(s) in RCA: 210] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2010] [Indexed: 10/19/2022]
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