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Coelho TR, Pereira HM, Bittencourt Guimarães AT. Physical function as a marker to assess the effects of occupational long-term pesticide exposure. PLoS One 2024; 19:e0300980. [PMID: 38728311 PMCID: PMC11086880 DOI: 10.1371/journal.pone.0300980] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 03/07/2024] [Indexed: 05/12/2024] Open
Abstract
In this cross-sectional study, we determined the relative impact of long-term occupational exposure to pesticides on physical performance and perception of tiredness. Experimental data was collected in locus from agricultural communities and included surveys to assess the duration of exposure to pesticides, social status, habitual physical activity levels, presence of common mental disorders (CMD), and self-reported tiredness. Plasmatic cholinesterase (PChE), body composition and traditional functional performance tests (Handgrip strength-HGS; Time up and go-TUG; and Sit-to-stand-STS) were obtained. From the 127 individuals tested, cluster analysis yielded 80 individuals divided in Direct Exposed (n = 37) and Indirect Exposed (n = 43); Tired (n = 16), and Not Tired (n = 64). PChE values were within the reference values (5209.64-13943.53 U/L). Pesticide exposure had no influence on PChE levels, CMD or fatigue (p > 0.05), while Self-reported tiredness had (p < 0.05). Principal Component Analyses showed that HGS; STS and TUG (i.e., physical performance variables) are negatively influenced by two independent factors: pesticide exposure and self-reported tiredness. We conclude that chronic pesticide exposure and tiredness can negatively impact physical performance, independently, without clinically significant changes in PChE levels that is a biomarker used to track pesticide intoxication. Functional physical tests can be a useful tool to identify chronic pesticide exposure, and help with the limitations of commonly used parameters (i.e. PChE and CMD). Self-reported tiredness is a confounding variable.
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Affiliation(s)
- Talita Regina Coelho
- Laboratory of Biological Investigations, Graduate Program in Biosciences and Health, State University of West Paraná (Unioeste), R. Universitária, Cascavel, PR, Brazil
- Department of Health Promotion and Surveillance Federal University of Latin American Integration (Unila), Avenida Tarquínio Joslin dos Santos, Foz do Iguaçu, PR, Brazil
| | - Hugo M. Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States of America
| | - Ana Tereza Bittencourt Guimarães
- Laboratory of Biological Investigations, Graduate Program in Biosciences and Health, State University of West Paraná (Unioeste), R. Universitária, Cascavel, PR, Brazil
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Pereira HM, Keenan KG, Hunter SK. Influence of visual feedback and cognitive challenge on the age-related changes in force steadiness. Exp Brain Res 2024:10.1007/s00221-024-06831-w. [PMID: 38613669 DOI: 10.1007/s00221-024-06831-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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 04/05/2024] [Indexed: 04/15/2024]
Abstract
Force steadiness can be influenced by visual feedback as well as presence of a cognitive tasks and potentially differs with age and sex. This study determined the impact of altered visual feedback on force steadiness in the presence of a difficult cognitive challenge in young and older men and women. Forty-nine young (19-30 yr; 25 women, 24 men) and 25 older (60-85 yr; 15 women; 10 men) performed low force (5% of maximum) static contractions with the elbow flexor muscles in the presence and absence of a cognitive challenge (counting backwards by 13) either with low or high visual feedback gain. The cognitive challenge reduced force steadiness (increased force fluctuation amplitude) particularly in women (cognitive challenge × sex: P < 0.05) and older individuals (cognitive challenge × age: P < 0.05). Force steadiness improved with high-gain visual feedback compared with low-gain visual feedback (P < 0.01) for all groups (all interactions: P > 0.05). Manipulation of visual feedback had no influence on the reduced force steadiness in presence of the cognitive challenge for all groups (all P > 0.05). These findings indicate that older individuals and women have greater risk of impaired motor performance of the upper extremity if steadiness is required during a low-force static contraction. Manipulation of visual feedback had minimal effects on the reduced force steadiness in presence of a difficult cognitive challenge.
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Affiliation(s)
- Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA.
| | - Kevin G Keenan
- Joseph J. Zilber College of Public Health, University of Wisconsin-Milwaukee, Milwaukee, USA
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, USA
- Athletic and Human Performance Research Center, Marquette University, Milwaukee, USA
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Peterson J, Chesbro G, Bemben MG, Larson RD, Pereira HM, Black CD. Delayed-Onset Muscle Soreness Alters Mechanical Sensitivity, but Not Thermal Sensitivity or Pain Modulatory Function. J Pain Res 2024; 17:571-581. [PMID: 38347855 PMCID: PMC10860815 DOI: 10.2147/jpr.s449787] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 01/30/2024] [Indexed: 02/15/2024] Open
Abstract
Introduction Many clinical musculoskeletal pain conditions are characterized by chronic inflammation that sensitizes nociceptors. An unresolved issue is whether inflammation affects all nociceptors in a similar manner. Exercise-induced muscle damage (EIMD) has been proposed as a model for simulating clinical inflammatory pain in healthy samples. We sought to test the effect of EIMD on various painful stimuli (pressure and thermal), central pain processing (via the nociceptive flexion reflex) and endogenous pain modulation via conditioned pain modulation and exercise-induced hypoalgesia. Methods Eighteen participants (9F, age: 24.6 ± 3.3) were recruited for repeated measures testing and each completed pain sensitivity testing prior to and 48 hours after an eccentric exercise protocol. The participants performed a minimum of 6 rounds of 10 eccentric knee extension exercises to induce muscle damage and localized inflammation in the right quadriceps. Force decrements, knee range-of-motion, and delayed onset muscle soreness (DOMS) were used to quantify EIMD. Results There was a significant main effect of time for pressure pain (%diff; -58.9 ± 23.1; p = 0.02, ηp2 = 0.28) but no significant main effect was observed for limb (%diff; -15.5 ± 23.9; p = 0.53, ηp2 = 0.02). In contrast, there was a significant interaction between time and limb (p < 0.001, ηp2 = 0.47) whereby participants had lower pressure pain sensitivity in the right leg only after the damage protocol (%diff; -105.9 ± 29.2; p = 0.002). Discussion Individuals with chronic inflammatory pain usually have an increased sensitivity to pressure, thermal, and electrical stimuli, however, our sample, following muscle damage to induce acute inflammation only had sensitivity to mechanical pain. Exercise induced inflammation may reflect a peripheral sensitivity localized to the damaged muscle rather than a global sensitivity like those with chronic pain display.
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Affiliation(s)
- Jessica Peterson
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA
- Department of Kinesiology, New Mexico State University, Las Cruces, NM, USA
- North Florida Foundation of Research and Education, Malcom Randall Veterans Medical Center, Gainesville, FL, USA
| | - Grant Chesbro
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA
| | - Michael G Bemben
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA
| | - Rebecca D Larson
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA
| | - Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA
| | - Christopher D Black
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA
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Delp M, Chesbro GA, Pribble BA, Miller RM, Pereira HM, Black CD, Larson RD. Higher rating of perceived exertion and lower perceived recovery following a graded exercise test during menses compared to non-bleeding days in untrained females. Front Physiol 2024; 14:1297242. [PMID: 38274043 PMCID: PMC10808339 DOI: 10.3389/fphys.2023.1297242] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 12/19/2023] [Indexed: 01/27/2024] Open
Abstract
The underrepresentation of the female population in exercise sciences could be attributed, at least in part, to difficulty in appropriately accounting for the effects of the menstrual cycle (MC). Previous studies examining the effects of the MC on aerobic performance and subjective measures of aerobic performance show conflicting results. Purpose: The study examined how the MC affects the objective and subjective measures of aerobic performance within untrained female participants and in comparison with untrained male participants assessed at similar time intervals. Methods: Twenty-one participants (12 females and 9 males) completed a graded exercise test (GXT) on a cycle ergometer. The female participants were tested during their early follicular (EF; menses), ovulatory (O), and mid-luteal (ML) phases of the MC. The male participants were included as the control group and were randomly assigned to a menstrual cycle phase for each visit. During GXT, maximal oxygen consumption (VO2max), respiratory exchange ratio (RER), maximal heart rate (HRmax), peak blood lactate, and rating of perceived exertion (RPE) were determined. Twenty-four hours post-exercise, the perceived recovery status (PRS) was assessed. The MC phase was estimated using basal body temperature (BBT) in the female participants. Results: The male participants obtained a higher peak power and VO2max compared to the female participants (p < 0.05). All objective measures of aerobic performance did not significantly differ across the MC phases or time points that were tested. In the untrained female participants, an effect of the MC phase on RPE was found, with RPE being higher at EF (8.92 ± 0.79) compared to O (7.67 ± 1.23; p < 0.05) and ML (7.75 ± 1.06; p < 0.05). In addition, an effect of the MC phase on PRS was found, with perceived recovery being lower at EF (6.83 ± 0.94) compared to O (8.83 ± 1.12) and ML (8.67 ± 0.65; all p < 0.005) for the untrained female participants. No significant differences in RPE and PRS were found between tests in the untrained male participants. The female participants had lower perceived recovery following EF (6.83 ± 0.94) compared with the male participants (9.00 ± 1.00; p < 0.001). Conclusion: The untrained female participants perceived greater exertion during GXT and impaired recovery following GXT in EF compared to O and ML. These results may be attributed to either a drop in female sex hormone concentrations or discomfort associated with menses. The male participants did not exhibit any changes over time. Future studies using subjective parameters such as perceived exertion to track the internal load of training in the naturally menstruating female population should consider menses.
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Affiliation(s)
- Morgan Delp
- Body Composition and Human Performance Lab, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Grant A. Chesbro
- Body Composition and Human Performance Lab, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Brian A. Pribble
- Body Composition and Human Performance Lab, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Ryan M. Miller
- Neuromuscular Research Lab, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Hugo M. Pereira
- Neuromuscular Research Lab, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Christopher D. Black
- Human Movement and Neurophysiology Lab, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Rebecca D. Larson
- Body Composition and Human Performance Lab, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
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Lino TB, Scarmagnan GS, Sobrinho-Junior SA, Tessari GMF, Gonçalves GH, Pereira HM, Christofoletti G. Impact of Using Smartphone While Walking or Standing: A Study Focused on Age and Cognition. Brain Sci 2023; 13:987. [PMID: 37508919 PMCID: PMC10376959 DOI: 10.3390/brainsci13070987] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/16/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND Using smartphones during a task that requires upright posture is suggested to be detrimental for the overall motor performance. The aim of this study was to determine the role of age and specific aspects of cognitive function on walking and standing tasks in the presence of smartphone use. METHODS 51 older (36 women) and 50 young (35 women), mean age: 66.5 ± 6.3 and 22.3 ± 1.7 years, respectively, were enrolled in this study. The impact of using a smartphone was assessed during a dynamic (timed up and go, TUG) and a static balance test (performed on a force platform). Multivariate analyses of variance were applied to verify main effects of age, task, estimates of cognitive function and interactions. RESULTS Compared to young, older individuals exhibited a poorer performance on the dynamic and on the static test (age effect: p = 0.001 for both variables). Dual-tasking with a smartphone had a negative impact on both groups (task effect: p = 0.001 for both variables). The negative impact, however, was greater in the older group (age × task effect: p = 0.001 for both variables). Executive function and verbal fluency partially explained results of the dynamic and static tests, respectively. CONCLUSIONS The negative impact of using a smartphone while performing tasks similar to daily activities is higher in older compared to young people. Subclinical deficits in distinct aspects of cognitive function partially explain the decreased performance when dual-tasking.
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Affiliation(s)
- Tayla B Lino
- School of Medicine, Institute of Health, Federal University of Mato Grosso do Sul, UFMS, Campo Grande 79060-900, Brazil
| | - Gabriella S Scarmagnan
- School of Medicine, Institute of Health, Federal University of Mato Grosso do Sul, UFMS, Campo Grande 79060-900, Brazil
| | - Sidney A Sobrinho-Junior
- School of Medicine, Institute of Health, Federal University of Mato Grosso do Sul, UFMS, Campo Grande 79060-900, Brazil
| | - Giovanna M F Tessari
- School of Medicine, Institute of Health, Federal University of Mato Grosso do Sul, UFMS, Campo Grande 79060-900, Brazil
| | - Glaucia H Gonçalves
- School of Medicine, Institute of Health, Federal University of Mato Grosso do Sul, UFMS, Campo Grande 79060-900, Brazil
| | - Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, OU 73019, USA
| | - Gustavo Christofoletti
- School of Medicine, Institute of Health, Federal University of Mato Grosso do Sul, UFMS, Campo Grande 79060-900, Brazil
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Pereira HM, Hunter SK. Cognitive challenge as a probe to expose sex- and age-related differences during static contractions. Front Physiol 2023; 14:1166218. [PMID: 37260592 PMCID: PMC10227451 DOI: 10.3389/fphys.2023.1166218] [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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 05/02/2023] [Indexed: 06/02/2023] Open
Abstract
Despite activities of daily living being frequently performed simultaneously with a cognitive task, motor function is often investigated in isolation, which can hinder the applicability of findings. This brief review presents evidence that 1) performing a cognitive challenge simultaneously with a motor task can negatively impact force steadiness and fatigability of limb muscles during a static contraction, 2) the negative impact on old adults (>65 years old), particularly older women is greater than young when a cognitive challenge is simultaneously performed with a static motor task, 3) age-related mechanisms potentially explain impairments in motor performance in the presence of a cognitive challenge, and 4) the mechanisms for the age-related decrements in motor performance can be distinct between men and women. These observations are highly relevant to the older adults, given the increased risk of accidents and injury when a motor task is performed with a high cognitive-demand task, especially in light of the expanding reliance on an aging workforce.
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Affiliation(s)
- Hugo M. Pereira
- Department of Health and Exercise Science, The University of Oklahoma, Norman, OK, United States
| | - Sandra K. Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, WI, United States
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Black CD, Peterson JA, Bemben MG, Larson RD, Pereira HM, Crowson HM. Symptomatic Covid-19 Infection Impairs Conditioned Pain Modulation But Not Exercise-induced Hypoalgesia. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000879304.29863.64] [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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Chow AMD, Shin J, Wang H, Kellawan JM, Pereira HM. Influence of Transcranial Direct Current Stimulation Dosage and Associated Therapy on Motor Recovery Post-stroke: A Systematic Review and Meta-Analysis. Front Aging Neurosci 2022; 14:821915. [PMID: 35370603 PMCID: PMC8972130 DOI: 10.3389/fnagi.2022.821915] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/14/2022] [Indexed: 11/21/2022] Open
Abstract
Purpose (1) To determine the impact of transcranial direct current stimulation (tDCS) applied alone or combined with other therapies on the recovery of motor function after stroke and (2) To determine tDCS dosage effect. Methods Randomized controlled trials comparing the effects of tDCS with sham, using the Barthel Index (BI), the upper and lower extremity Fugl–Meyer Assessment (FMA), and the Modified Ashworth Scale (MAS), were retrieved from PubMed, Medline (EBSCO), and Cumulative Index to Nursing and Allied Health Literature (CINAHL) from their inception to June 2021. Calculations for each assessment were done for the overall effect and associated therapy accounting for the influence of stroke severity or stimulation parameters. Results A total of 31 studies involving metrics of the BI, the upper extremity FMA, the lower extremity FMA, and the MAS were included. tDCS combined with other therapies was beneficial when assessed by the BI (mean difference: 6.8; P < 0.01) and these studies typically had participants in the acute stage. tDCS effects on the upper and lower extremity FMA are unclear and differences between the sham and tDCS groups as well as differences in the associated therapy type combined with tDCS potentially influenced the FMA results. tDCS was not effective compared to sham for the MAS. Stimulation types (e.g., anodal vs. cathodal) did not influence these results and dosage parameters were not associated with the obtained effect sizes. Conventional therapy associated with tDCS typically produced greater effect size than assisted therapy. The influence of stroke severity is unclear. Conclusion Potential benefits of tDCS can vary depending on assessment tool used, duration of stroke, and associated therapy. Mechanistic studies are needed to understand the potential role of stimulation type and dosage effect after stroke. Future studies should carefully conduct group randomization, control for duration of stroke, and report different motor recovery assessments types. Systematic Review Registration [https://www.crd.york.ac.uk/PROSPERO/], identifier [CRD42021290670].
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Affiliation(s)
- Alan-Michael D. Chow
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Jeonghwa Shin
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Hongwu Wang
- Department of Occupational Therapy, University of Florida, Gainesville, FL, United States
| | - Jeremy Mikhail Kellawan
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Hugo M. Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
- *Correspondence: Hugo M. Pereira,
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Maciel MJ, Pereira HM, Pimenta S, Miranda A, Nunes-Pereira EJ, Correia JH. Differentiation between normal and tumor mammary glands with depth-resolved attenuation coefficient from optical coherence tomography. Biomed Phys Eng Express 2021; 8. [PMID: 34753120 DOI: 10.1088/2057-1976/ac37ca] [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: 07/27/2021] [Accepted: 11/09/2021] [Indexed: 11/11/2022]
Abstract
Optical coherence tomography (OCT) is a well-established imaging technology for high-resolution, cross-sectional imaging of biological tissues. Imaging processing and light attenuation coefficient estimation allows to further improve the OCT diagnostic capability. In this paper we use a commercial OCT system, Telesto II-1325LR from Thorlabs, and demonstrate its ability to differentiate normal and tumor mammary mouse glands with the OCT attenuation coefficient. Using several OCT images of normal and tumor mammary mouse glands (n = 26), a statistical analysis was performed. The attenuation coefficient was calculated in depth, considering a slope of 0.5 mm. The normal glands present a median attenuation coefficient of 0.403 mm-1, comparatively to 0.561 mm-1obtained for tumor mammary glands. This translates in an attenuation coefficient approximately 39% higher for tumor mammary glands when compared to normal mammary glands. The OCT attenuation coefficient estimation eliminates the subjective analysis provided by direct visualization of the OCT images.
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Affiliation(s)
| | | | - Sara Pimenta
- CMEMS-UMinho, University of Minho, Guimarães, Portugal
| | - Alice Miranda
- ICVS, School of Medicine, University of Minho, ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Eduardo J Nunes-Pereira
- Centre of Physics of Minho and Porto Universities (CF-UM-UP), University of Minho, Braga, Portugal
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Miller RM, Heishman AD, Freitas ED, Peak KM, Carr JC, Buchanan SR, Kellawan JM, Pereira HM, Bemben DA, Bemben MG. Midthigh Muscle Composition Across The Adult Female Lifespan. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000760632.91046.17] [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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11
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Freitas EDS, Miller RM, Heishman AD, Peak KM, Bemben DA, Larson RD, Pereira HM, Bemben MG. The Physiological Responses Of Multiple Sclerosis Patients To Blood Flow Restriction Versus Traditional Resistance Exercise. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000764468.92254.2f] [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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Giersch GEW, Charkoudian N, Pereira T, Edgell H, Freeberg KA, Craighead DH, Neill M, Allison EY, Zapcic AK, Smith KJ, Bock JM, Casey DP, Shenouda N, Ranadive SM, Tremblay JC, Williams AM, Simpson LL, Meah VL, Ruediger SL, Bailey TG, Pereira HM, Lei TH, Perry B, Mündel T, Freemas JA, Worley ML, Baranauskas MN, Carter SJ, Johnson BD, Schlader ZJ, Bates LC, Stoner L, Zieff G, Poles J, Adams N, Meyer ML, Hanson ED, Greenlund IM, Bigalke JA, Carter JR, Kerr ZY, Stanford K, Pomeroy A, Boggess K, de Souza HLR, Meireles A, Arriel RA, Leite LHR, Marocolo M, Chapman CL, Atencio JK, Kaiser BW, Comrada LN, Halliwill JR, Minson CT, Williams JS, Dunford EC, MacDonald MJ, Santisteban KJ, Larson EA, Reed E, Needham KW, Gibson BM, Gillen J, Barbosa TC, Cardoso LLY, Gliemann L, Tamariz-Ellemann A, Hellsten Y, DuBos LE, Babcock MC, Moreau KL, Wickham KA, Vagula M, Moir ME, Klassen SA, Rodrigues A. Commentaries on Point:Counterpoint: Investigators should/should not control for menstrual cycle phase when performing studies of vascular control. J Appl Physiol (1985) 2021; 129:1122-1135. [PMID: 33197376 DOI: 10.1152/japplphysiol.00809.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, Massachusetts,Oak Ridge Institute for Science and Education, Oak Ridge, Tennnessee
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, Massachusetts
| | - T Pereira
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada
| | - H Edgell
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada
| | - Kaitlin A Freeberg
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado
| | - Daniel H Craighead
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado
| | - Matthew Neill
- Department of Kinesiology, Lakehead University, Thunder Bay, Ontario, Canada
| | - Elric Y Allison
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Andrea K Zapcic
- Department of Kinesiology, Lakehead University, Thunder Bay, Ontario, Canada
| | - Kurt J Smith
- Integrative Physiology Lab, Department of Kinesiology and Nutrition, University of Chicago, Chicago, Illinois
| | - Joshua M Bock
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Darren P Casey
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa,Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa,Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Ninette Shenouda
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Sushant M Ranadive
- Department of Kinesiology, University of Maryland, College Park, Maryland
| | - Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, University of British Columbia–Okanagan, Kelowna, British Columbia, Canada
| | - Alexandra M Williams
- Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, Canada,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, Canada
| | - Lydia L Simpson
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, United Kingdom
| | - Victoria L Meah
- Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport, and Recreation, Women and Children's Health Research Institute, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Stefanie L Ruediger
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre of Research on Exercise, Physical Activity and Health, The University of Queensland, Australia
| | - Tom G Bailey
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre of Research on Exercise, Physical Activity and Health, The University of Queensland, Australia,School of Nursing, Midwifery and Social Work, The University of Queensland, Australia
| | - Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma
| | - Tze-Huan Lei
- College of Physical Education, Hubei Normal University, Huangshi, China,Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Blake Perry
- School of Health Sciences, Massey University, Wellington, New Zealand
| | - Toby Mündel
- School of Sport Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| | - Jessica A Freemas
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Morgan L Worley
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Marissa N Baranauskas
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Stephen J Carter
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Blair D Johnson
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Zachary J Schlader
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Lauren C Bates
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Lee Stoner
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Gabriel Zieff
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jillian Poles
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Nathan Adams
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michelle L Meyer
- Department of Emergency Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Erik D Hanson
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Ian M Greenlund
- Department of Health and Human Development, Montana State University, Bozeman, Montana,Department of Psychology, Montana State University, Bozeman, Montana
| | - Jeremy A Bigalke
- Department of Health and Human Development, Montana State University, Bozeman, Montana,Department of Psychology, Montana State University, Bozeman, Montana
| | - Jason R Carter
- Department of Health and Human Development, Montana State University, Bozeman, Montana,Department of Psychology, Montana State University, Bozeman, Montana
| | - Zachary Y Kerr
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Kathleen Stanford
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Alex Pomeroy
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Kim Boggess
- Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Hiago L R de Souza
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Anderson Meireles
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Rhai A Arriel
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Laura H R Leite
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Moacir Marocolo
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | | | - Jessica K Atencio
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Brendan W Kaiser
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Lindan N Comrada
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - John R Halliwill
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | | | - Jennifer S Williams
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Emily C Dunford
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Maureen J MacDonald
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | | | - Emily A Larson
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Emma Reed
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Karen W Needham
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Brandon M Gibson
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Jenna Gillen
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Canada
| | - Thales C Barbosa
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
| | - Licy L Yanes Cardoso
- Department of Cell and Molecular Biology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Lasse Gliemann
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | | | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Lyndsey E DuBos
- Division of Geriatric Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Matthew C Babcock
- Division of Geriatric Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Kerrie L Moreau
- Division of Geriatric Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado,Veterans Affairs Eastern Colorado Geriatric Research, Educational and Clinical Center, Denver, Colorado
| | - Kate A Wickham
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | | | - M Erin Moir
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | | | - Alex Rodrigues
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
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Pereira HM, de Lima FF, Silva BM, Kohn AF. Sex differences in fatigability after ischemic preconditioning of non-exercising limbs. Biol Sex Differ 2020; 11:59. [PMID: 33109241 PMCID: PMC7590792 DOI: 10.1186/s13293-020-00338-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/18/2020] [Indexed: 12/11/2022] Open
Abstract
Background Ischemic preconditioning (IPC) is suggested to decrease fatigability in some individuals but not others. Sex differences in response to IPC may account for this variability and few studies systematically investigated the effects of IPC in men and women. The goal of this study was to determine if time to task failure, perception of pain, and neuromuscular mechanisms of fatigability were altered by IPC in men and women. Methods Ten women (29 ± 5 years old) and 10 men (28 ± 6 years old) performed isometric contractions with the plantar flexor muscles of the dominant leg at 20% of maximal voluntary contraction until task failure. We used a repeated measures design where each individual performed 3 randomized and counterbalanced test sessions: (A) IPC session, cuff inflation and deflation (5 min each repeated 3 times) performed before the exercise by inflating cuffs to the non-dominant leg and arm; (B) sham session, cuffs were inflated for a short period (1 min); and (C) control session, no cuffs were involved. Results Compared with control, IPC increased time to task failure in men (mean difference, 5 min; confidence interval (CI) of mean difference, 2.2; 7.8 min; P = 0.01) but not women (mean difference, − 0.6 min; CI of mean difference, − 3.5; 2.4 min; P = 0.51). In men, but not women, the IPC-induced increase in time to task failure was associated with lower response to pressure pain (r = − 0.79). IPC further exposed sex differences in arterial pressure during fatiguing contractions (session × sex: P < 0.05). Voluntary activation, estimated with the twitch interpolation technique, and presynaptic inhibition of leg Ia afferents were not altered after IPC for men and women. The tested variables were not altered with sham. Conclusions The ergogenic effect of IPC on time to task failure was observed only in men and it was associated with reductions in the perception of pain. This pilot data suggest the previously reported inter-individual variability in exercise-induced fatigability after IPC could be a consequence of the sex and individual response to pain.
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Affiliation(s)
- Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma, 1401 Asp Ave, Norman, OK, 73019, USA.
| | - Felipe F de Lima
- Biomedical Engineering Laboratory/EPUSP, University of São Paulo, São Paulo, SP, Brazil
| | - Bruno M Silva
- Department of Physiology, Federal University of São Paulo, São Paulo, SP, Brazil
| | - André F Kohn
- Biomedical Engineering Laboratory/EPUSP, University of São Paulo, São Paulo, SP, Brazil
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Delesalle Q, Lopes AM, Gawor JP, Zani D, Pereira HM, Mestrinho LA. Comparative morphometry of the temporomandibular joint in brachycephalic and mesocephalic cats using multislice CT and cone beam CT. J Feline Med Surg 2020; 23:507-512. [PMID: 33030097 DOI: 10.1177/1098612x20960657] [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] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The purpose of this study was to analyse and compare morphometric measurements of the temporomandibular joint (TMJ) in two groups of cats with brachycephalic and mesocephalic craniofacial skull conformations using multislice CT and cone beam CT. METHODS CT records of 20 cats without TMJ pathology were included in the study, and were divided into two groups according to those with mesocephalic or brachycephalic skull conformation. Width and depth of the mandibular fossa, width and height of the head of the mandible, and two different angles were measured in 40 TMJs. RESULTS TMJ conformation differed between groups: 3/6 parameters were statistically different. Brachycephalic cats had a significantly narrower mandibular fossa, a shorter head of the mandible and a wider angle of congruence (angle 2). CONCLUSIONS AND RELEVANCE The results provide morphometric measurements that can serve as a reference tool for the veterinary radiologist and surgeon when TMJ evaluation is necessary. Moreover, the study identified significant differences between the two craniofacial skull conformations.
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Affiliation(s)
| | - António M Lopes
- Centro de Investigação Interdisciplinar em Sanidade Animal (CIISA), Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portugal
| | | | - Davide Zani
- Department of Veterinary Radiology, Academic Veterinary Hospital, University of Milan, Lodi, Italy
| | | | - Lisa A Mestrinho
- Centro de Investigação Interdisciplinar em Sanidade Animal (CIISA), Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portugal
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15
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Miller RM, Heishman AD, Freitas ED, Buchanan SR, Kaur J, Brown BS, Peak KM, Norman JN, Joniak KE, Kellawan JM, Pereira HM, Bemben DA, Bemben MG. Critical Ages For Changes In Isometric Force Production In Women Aged 20 To 89 Years. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000680288.18980.b0] [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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16
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Freitas EDS, Miller RM, Heishman AD, Kaur J, Peak KM, Combs C, Bemben DA, Larson R, Pereira HM, Bemben MG. The Perceptual Responses Of Multiple Sclerosis Patients To Traditional Versus Blood Flow Restriction Resistance Exercise. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000681200.43988.56] [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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17
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Abstract
Estrogen and progesterone have distinct concentrations across the menstrual cycle, each one promoting several physiological alterations other than preparing the uterus for pregnancy. Whether these physiological alterations can influence motor output during a fatiguing contraction is the goal of this review, with an emphasis on the obtained effect sizes. Studies on this topic frequently attempt to report if there is a statistically significant difference in fatigability between the follicular and luteal phases of the menstrual cycle. Although the significant difference (the P-value) can inform the probability of the event, it does not indicate the magnitude of it. We also investigated whether the type of task performed (e.g., isometric vs. dynamic) can further influence the magnitude by which exercise-induced fatigue changes with fluctuations in the concentration of ovarian hormones. We retrieved experimental studies in eumenorrheic women published between 1975 and 2019. The initial search yielded 921 studies, and after manual refinement, 46 experimental studies that reported metrics of motor output in both the follicular and luteal phases of the menstrual cycle were included. From these retrieved studies, 15 showed a statistical difference between the luteal and follicular phases (seven showing less fatigability during the luteal phase and eight during the follicular phase). The effect size was not consistent across studies and with a large range (-6.77; 1.61, favoring the luteal and follicular phase, respectively). The inconsistencies across studies may be a consequence of the differences in the limb used during the fatiguing contraction (upper vs. lower extremity), the type of contraction (isometric vs. dynamic), the muscle mass engaged (single limb vs. full body), and the techniques used to define the menstrual cycle phase (e.g., serum concentration vs. reported day of menses). Further studies are required to determine the effects of a regular menstrual cycle phase on the exercise-induced fatigability.
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Affiliation(s)
- Hugo M. Pereira
- Department of Health and Exercise Science, The University of Oklahoma, Norman, OK, United States
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18
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Senefeld J, Pereira HM, Elliott N, Yoon T, Hunter SK. Sex Differences in Mechanisms of Recovery after Isometric and Dynamic Fatiguing Tasks. Med Sci Sports Exerc 2019; 50:1070-1083. [PMID: 29298217 DOI: 10.1249/mss.0000000000001537] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The purpose of this study was to determine whether supraspinal mechanisms contribute to the sex difference in fatigability during and recovery from a dynamic and isometric fatiguing task with the knee extensors. METHODS Transcranial magnetic stimulation and electrical stimulation were used to determine voluntary activation and contractile properties of the knee extensors in 14 men and 17 women (20.8 ± 1.9 yr) after a 1) 60-s sustained, maximal voluntary isometric contraction (MVIC), and 2) dynamic fatiguing task involving 120 maximal voluntary concentric contractions with a 20% MVIC load. RESULTS There were no differences between men and women in the reduction of maximal torque during the sustained MVIC (54.4% ± 18.9% vs 55.9% ± 11.2%, P = 0.49) or in the decrease in power during the dynamic fatiguing task (14.7% ± 20.1% vs 14.2% ± 18.5%, P = 0.92). However, MVIC torque recovered more quickly for women than men after the sustained MVIC and the dynamic task (P < 0.05). The transcranial magnetic stimulation-elicited superimposed twitch was larger for men than for women during the sustained MVIC and in recovery (immediately post, R0.1: 4.7% ± 3.3% vs 2.4% ± 1.9% MVIC; P = 0.02), with no sex difference after the dynamic task (P = 0.35). The reduction in resting twitch amplitude was larger for men than for women immediately after the dynamic task (37% ± 22% vs 23% ± 18%; P = 0.016) with no sex difference after the sustained MVIC (64% ± 16% vs 67% ± 11%; P = 0.46). CONCLUSIONS Supraspinal fatigue contributed to fatigability of the knee extensors more for men than for women after a maximal isometric task, whereas contractile mechanisms explained the sex difference in torque recovery after the fast-velocity dynamic task. The mechanisms for the sex difference in fatigability are task dependent.
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Affiliation(s)
- Jonathon Senefeld
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Hugo M Pereira
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Nicholas Elliott
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Tejin Yoon
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI
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Pereira HM, Schlinder-DeLap B, Keenan KG, Negro F, Farina D, Hyngstrom AS, Nielson KA, Hunter SK. Oscillations in neural drive and age-related reductions in force steadiness with a cognitive challenge. J Appl Physiol (1985) 2019; 126:1056-1065. [PMID: 30817244 DOI: 10.1152/japplphysiol.00821.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
A cognitive challenge when imposed during a low-force isometric contraction will exacerbate sex- and age-related decreases in force steadiness, but the mechanism is not known. We determined the role of oscillations in the common synaptic input to motor units on force steadiness during a muscle contraction with a concurrent cognitive challenge. Forty-nine young adults (19-30 yr; 25 women, 24 men) and 36 old adults (60-85 yr; 19 women, 17 men) performed a cognitive challenge (counting backward by 13) during an isometric elbow flexion task at 5% of maximal voluntary contraction. Single-motor units were decomposed from high-density surface EMG recordings. For a subgroup of participants, motor units were matched during control and cognitive challenge trials, so the same motor unit was analyzed across conditions. Reduced force steadiness was associated with greater oscillations in the synaptic input to motor units during both control and cognitive challenge trials ( r = 0.45-0.47, P < 0.01). Old adults and young women showed greater oscillations in the common synaptic input to motor units and decreased force steadiness when the cognitive challenge was imposed, but young men showed no change across conditions (session × age × sex, P < 0.05). Oscillations in the common synaptic input to motor units is a potential mechanism for altered force steadiness when a cognitive challenge is imposed during low-force contractions in young women and old adults. NEW & NOTEWORTHY We found that oscillations in the common synaptic input to motor units were associated with a reduction in force steadiness when a cognitive challenge was imposed during low-force contractions of the elbow flexor muscles in young women and old men and women but not young men. Age- and sex-related muscle weakness was associated with these changes.
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Affiliation(s)
- Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma , Norman, Oklahoma
| | | | - Kevin G Keenan
- Department of Kinesiology, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Università degli Studi di Brescia , Brescia , Italy
| | - Dario Farina
- Department of Bioengineering, Imperial College London, Royal School of Mines , London , United Kingdom
| | | | - Kristy A Nielson
- Department of Psychology, Marquette University , Milwaukee, Wisconsin
| | - Sandra K Hunter
- Department of Physical Therapy, Marquette University , Milwaukee, Wisconsin
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20
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Pereira HM, Schlinder-Delap B, Nielson KA, Hunter SK. Force Steadiness During a Cognitively Challenging Motor Task Is Predicted by Executive Function in Older Adults. Front Physiol 2018; 9:1316. [PMID: 30333758 PMCID: PMC6176355 DOI: 10.3389/fphys.2018.01316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [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: 04/28/2018] [Accepted: 08/30/2018] [Indexed: 12/12/2022] Open
Abstract
Motor performance and cognitive function both decline with aging. Older adults for example are usually less steady for a constant-force task than young adults when performing low-intensity contractions with limb muscles. Healthy older adults can also show varying degrees of cognitive decline, particularly in executive function skills. It is not known, however, whether age-related changes in steadiness of low-force tasks and cognitive function are independent of one another. In this study, we determined if executive function skills in aging are associated with the steadiness during a low-force muscle contraction performed with and without the imposition of a cognitive challenge. We recruited 60 older adults (60–85 years old, 34 women, 26 men) and 48 young adults (19–30 years old, 24 women, 24 men) to perform elbow flexor muscle contractions at 5% of maximal voluntary contraction (MVC) force in the presence and absence of a difficult mental-math task (counting backward by 13 from a four-digit number). Force steadiness was quantified as the coefficient of variation (CV) of force and executive function was estimated with the Trail-making Test part A and B. The cognitive challenge increased the CV of force (i.e., decreased force steadiness) with greater changes in older adults than young adults (5.2 vs. 1.3%, respectively, cognitive challenge × age: P < 0.001). Older adults were 35% slower in both parts A and B of the Trail-making Test (P < 0.001), and to eliminate the effects of age and education on this variable, all further analyses were performed with the age-corrected z-scores for each individual using established normative values. Hierarchical regression models indicated that decreased force steadiness during a cognitive challenge trial was in part, explained by the performance in the Trail-making Test part A and B in older (r = 0.53 and 0.50, respectively, P < 0.05), but not in young adults (P > 0.05). Thus, healthy community-dwelling older adults, who have poorer executive function skills, exhibit reduced force steadiness during tasks when also required to perform a high cognitive demand task, and are likely at risk of reduced capacity to perform daily activities that involve cognitively challenging motor tasks.
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Affiliation(s)
- Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, United States
| | - Bonnie Schlinder-Delap
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, United States
| | - Kristy A Nielson
- Department of Psychology, Marquette University, Milwaukee, WI, United States
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, United States
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21
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Pereira HM, Silva BM, Kohn AF. Fatigability of Plantar Flexor Muscles After Remote Ischemic Preconditioning. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536530.07117.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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Abstract
Age-related changes in the basic functional unit of the neuromuscular system, the motor unit, and its neural inputs have a profound effect on motor function, especially among the expanding number of old (older than ∼60 yr) and very old (older than ∼80 yr) adults. This review presents evidence that age-related changes in motor unit morphology and properties lead to impaired motor performance that includes 1) reduced maximal strength and power, slower contractile velocity, and increased fatigability; and 2) increased variability during and between motor tasks, including decreased force steadiness and increased variability of contraction velocity and torque over repeat contractions. The age-related increase in variability of motor performance with aging appears to involve reduced and more variable synaptic inputs that drive motor neuron activation, fewer and larger motor units, less stable neuromuscular junctions, lower and more variable motor unit action potential discharge rates, and smaller and slower skeletal muscle fibers that coexpress different myosin heavy chain isoforms in the muscle of older adults. Physical activity may modify motor unit properties and function in old men and women, although the effects on variability of motor performance are largely unknown. Many studies are of cross-sectional design, so there is a tremendous opportunity to perform high-impact and longitudinal studies along the continuum of aging that determine 1) the influence and cause of the increased variability with aging on functional performance tasks, and 2) whether lifestyle factors such as physical exercise can minimize this age-related variability in motor performance in the rapidly expanding numbers of very old adults.
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Affiliation(s)
- Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin; and
| | - Hugo M Pereira
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin; and
| | - Kevin G Keenan
- Department of Kinesiology, College of Health Sciences, University of Wisconsin, Milwaukee, Wisconsin
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23
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Hilbers JP, Schipper AM, Hendriks AJ, Verones F, Pereira HM, Huijbregts MAJ. An allometric approach to quantify the extinction vulnerability of birds and mammals. Ecology 2016; 97:615-26. [PMID: 27197389 DOI: 10.1890/14-2019.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Methods to quantify the vulnerability of species to extinction are typically limited by the availability of species-specific input data pertaining to life-history characteristics and population dynamics. This lack of data hampers global biodiversity assessments and conservation planning. Here, we developed a new framework that systematically quantifies extinction risk based on allometric relationships between various wildlife demographic parameters and body size. These allometric relationships have a solid theoretical and ecological foundation. Extinction risk indicators included are (1) the probability of extinction, (2) the mean time to extinction, and (3) the critical patch size. We applied our framework to assess the global extinction vulnerability of terrestrial carnivorous and non-carnivorous birds and mammals. Irrespective of the indicator used, large-bodied species were found to be more vulnerable to extinction than their smaller counterparts. The patterns with body size were confirmed for all species groups by a comparison with IUCN data on the proportion of extant threatened species: the models correctly predicted a multimodal distribution with body size for carnivorous birds and a monotonic distribution for mammals and non-carnivorous birds. Carnivorous mammals were found to have higher extinction risks than non-carnivores, while birds were more prone to extinction than mammals. These results are explained by the allometric relationships, predicting the vulnerable species groups to have lower intrinsic population growth rates, smaller population sizes, lower carrying capacities, or larger dispersal distances, which, in turn, increase the importance of losses due to environmental stochastic effects and dispersal activities. Our study is the first to integrate population viability analysis and allometry into a novel, process-based framework that is able to quantify extinction risk of a large number of species without requiring data-intensive, species-specific information. The framework facilitates the estimation of extinction vulnerabilities of data-deficient species. It may be applied to forecast extinction vulnerability in response to a changing environment, by incorporating quantitative relationships between wildlife demographic parameters and environmental drivers like habitat alteration, climate change, or hunting.
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Pereira HM, Spears VC, Schlinder-Delap B, Yoon T, Harkins A, Nielson KA, Hoeger Bement M, Hunter SK. Sex Differences in Arm Muscle Fatigability With Cognitive Demand in Older Adults. Clin Orthop Relat Res 2015; 473:2568-77. [PMID: 25712862 PMCID: PMC4488210 DOI: 10.1007/s11999-015-4205-1] [Citation(s) in RCA: 16] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Muscle fatigability can increase when a stressful, cognitively demanding task is imposed during a low-force fatiguing contraction with the arm muscles, especially in women. Whether this occurs among older adults (>60 years) is currently unknown. QUESTIONS/PURPOSES We aimed to determine if higher cognitive demands, stratified by sex, increased fatigability in older adults (>60 years). Secondarily, we assessed if varying cognitive demand resulted in decreased steadiness and was explained by anxiety or cortisol levels. METHODS Seventeen older women (70±6 years) and 13 older men (71±5 years) performed a sustained, isometric, fatiguing contraction at 20% of maximal voluntary contraction until task failure during three sessions: high cognitive demand (high CD=mental subtraction by 13); low cognitive demand (low CD=mental subtraction by 1); and control (no subtraction). RESULTS Fatigability was greater when high and low CD were performed during the fatiguing contraction for the women but not for the men. In women, time to failure with high CD was 16±8 minutes and with low CD was 17±4 minutes, both of which were shorter than time to failure in control contractions (21±7 minutes; high CD mean difference: 5 minutes [95% confidence interval {CI}, 0.78-9.89], p=0.02; low CD mean difference: 4 minutes [95% CI, 0.57-7.31], p=0.03). However, in men, no differences were detected in time to failure with cognitive demand (control: 13±5 minutes; high CD mean difference: -0.09 minutes [95% CI, -2.8 to 2.7], p=1.00; low CD mean difference: 0.75 minutes [95% CI, -1.1 to 2.6], p=0.85). Steadiness decreased (force fluctuations increased) more during high CD than control. Elevated anxiety, mean arterial pressure, and salivary cortisol levels in both men and women did not explain the greater fatigability during high CD. CONCLUSIONS Older women but not men showed marked increases in fatigability when low or high CD was imposed during sustained static contractions with the elbow flexor muscles and contrasts with previous findings for the lower limb. Steadiness decreased in both sexes when high CD was imposed. CLINICAL RELEVANCE Older women are susceptible to greater fatigability of the upper limb with heightened mental activity during sustained postural contractions, which are the foundation of many work-related tasks.
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Affiliation(s)
- Hugo M. Pereira
- Department of Physical Therapy, Marquette University, PO Box 1881, Milwaukee, WI 53201 USA
| | - Vincent C. Spears
- Department of Physical Therapy, Marquette University, PO Box 1881, Milwaukee, WI 53201 USA
| | - Bonnie Schlinder-Delap
- Department of Physical Therapy, Marquette University, PO Box 1881, Milwaukee, WI 53201 USA
| | - Tejin Yoon
- Michigan Technological University, Houghton, MI USA
| | - April Harkins
- Department of Clinical Laboratory Sciences, Marquette University, Milwaukee, WI USA
| | | | - Marie Hoeger Bement
- Department of Physical Therapy, Marquette University, PO Box 1881, Milwaukee, WI 53201 USA
| | - Sandra K. Hunter
- Department of Physical Therapy, Marquette University, PO Box 1881, Milwaukee, WI 53201 USA
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Pereira HM, Esser TJ, Schlinder-Delap B, Senefeld J, Sundberg CW, Deering R, Hunter SK. Cognitive Demand Decreases Steadiness and Dexterity with Aging. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000478351.48030.72] [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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Deering R, Senefeld J, Pashibin T, Pereira HM, Hoeger-Bement M, Eickmeyer S, Hunter SK. Fatigability And Steadiness Of The Trunk Flexor Muscles In Young, Healthy Adults. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000476952.63675.1d] [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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Pereira HM, Spears VC, Schlinder-Delap B, Yoon T, Nielson KA, Hunter SK. Age and sex differences in steadiness of elbow flexor muscles with imposed cognitive demand. Eur J Appl Physiol 2015; 115:1367-79. [PMID: 25633070 DOI: 10.1007/s00421-015-3113-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 01/14/2015] [Indexed: 01/25/2023]
Abstract
PURPOSE These studies determined (1) age- and sex-related differences in steadiness of isometric contractions when high cognitive demand was imposed across a range of forces with the elbow flexor muscles (study 1) and; (2) sex differences in steadiness among older adults when low cognitive demand was imposed (study 2). METHODS 36 young adults (18-25 years; 18 women) and 30 older adults (60-82 years; 17 women) performed isometric contractions at 5, 30 and 40 % of maximum voluntary contraction (MVC). Study 1 involved a high-cognitive demand session (serial subtractions by 13 during the contraction) and a control session (no mental math). Study 2 (older adults only) involved a low-cognitive demand session (subtracting by 1s). RESULTS Older individuals exhibited greater increases in force fluctuations (coefficient of variation of force, CV) with high cognitive demand than young adults, with the largest age difference at 5 % MVC (P = 0.01). Older adults had greater agonist EMG activity with high-cognitive demand and women had greater coactivation than men (P < 0.05). In study 2, CV of force increased with low cognitive demand for the older women but not for the older men (P = 0.03). CONCLUSION Older adults had reduced steadiness and increased muscle activation when high cognitive demand was imposed while low cognitive demand induced increased force fluctuations in older women but not older men. These findings have implications for daily and work-related tasks that involve cognitive demand performed simultaneously during submaximal isometric contractions in an aging workforce.
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Affiliation(s)
- Hugo M Pereira
- Department of Physical Therapy, Marquette University, P.O. Box 1881, Milwaukee, WI, 53201, USA
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Vanden Noven ML, Pereira HM, Yoon T, Stevens AA, Nielson KA, Hunter SK. Motor Variability during Sustained Contractions Increases with Cognitive Demand in Older Adults. Front Aging Neurosci 2014; 6:97. [PMID: 24904410 PMCID: PMC4033244 DOI: 10.3389/fnagi.2014.00097] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [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: 03/03/2014] [Accepted: 05/05/2014] [Indexed: 01/26/2023] Open
Abstract
To expose cortical involvement in age-related changes in motor performance, we compared steadiness (force fluctuations) and fatigability of submaximal isometric contractions with the ankle dorsiflexor muscles in older and young adults and with varying levels of cognitive demand imposed. Sixteen young (20.4 ± 2.1 year: 8 men, 9 women) and 17 older adults (68.8 ± 4.4 years: 9 men, 8 women) attended three sessions and performed a 40 s isometric contraction at 5% maximal voluntary contraction (MVC) force followed by an isometric contraction at 30% MVC until task failure. The cognitive demand required during the submaximal contractions in each session differed as follows: (1) high-cognitive demand session where difficult mental math was imposed (counting backward by 13 from a 4-digit number); (2) low-cognitive demand session which involved simple mental math (counting backward by 1); and (3) control session with no mental math. Anxiety was elevated during the high-cognitive demand session compared with other sessions for both age groups but more so for the older adults than young adults (p < 0.05). Older adults had larger force fluctuations than young adults during: (1) the 5% MVC task as cognitive demand increased (p = 0.007), and (2) the fatiguing contraction for all sessions (p = 0.002). Time to task failure did not differ between sessions or age groups (p > 0.05), but the variability between sessions (standard deviation of three sessions) was greater for older adults than young (2.02 ± 1.05 vs. 1.25 ± 0.51 min, p < 0.05). Thus, variability in lower limb motor performance for low- and moderate-force isometric tasks increased with age and was exacerbated when cognitive demand was imposed, and may be related to modulation of synergist and antagonist muscles and an altered neural strategy with age originating from central sources. These data have significant implications for cognitively demanding low-force motor tasks that are relevant to functional and ergonomic in an aging workforce.
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Affiliation(s)
- Marnie L Vanden Noven
- Exercise Science Program, Department of Physical Therapy, Marquette University , Milwaukee, WI , USA
| | - Hugo M Pereira
- Exercise Science Program, Department of Physical Therapy, Marquette University , Milwaukee, WI , USA
| | - Tejin Yoon
- Exercise Science Program, Department of Physical Therapy, Marquette University , Milwaukee, WI , USA
| | - Alyssa A Stevens
- Exercise Science Program, Department of Physical Therapy, Marquette University , Milwaukee, WI , USA
| | - Kristy A Nielson
- Department of Psychology, Marquette University , Milwaukee, WI , USA
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University , Milwaukee, WI , USA
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Pereira HM, Schlinder-Delap B, Yoon T, Keenan KG, Hunter SK. Cognitive Stress and Visual Gain Affects Force Fluctuations at Low Forces. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000495501.30221.61] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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-Ross ML, Pereira HM, Pruse J, Yoon T, Schlinder-Delap B, Nielson KA, Hunter SK. Stressor-induced increase in muscle fatigability of young men and women is predicted by strength but not voluntary activation. J Appl Physiol (1985) 2014; 116:767-78. [PMID: 24526582 DOI: 10.1152/japplphysiol.01129.2013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study investigated mechanisms for the stressor-induced changes in muscle fatigability in men and women. Participants performed an isometric-fatiguing contraction at 20% maximal voluntary contraction (MVC) until failure with the elbow flexor muscles. Study one (n = 55; 29 women) involved two experimental sessions: 1) a high-stressor session that required a difficult mental-math task before and during a fatiguing contraction and 2) a control session with no mental math. For some participants (n = 28; 14 women), cortical stimulation was used to examine mechanisms that contributed to muscle fatigability during the high-stressor and control sessions. Study two (n = 23; nine women) determined the influence of a low stressor, i.e., a simple mental-math task, on muscle fatigability. In study one, the time-to-task failure was less for the high-stressor session than control (P < 0.05) for women (19.4%) and men (9.5%): the sex difference response disappeared when covaried for initial strength (MVC). MVC force, voluntary activation, and peak-twitch amplitude decreased similarly for the control and high-stressor sessions (P < 0.05). In study two, the time-to-task failure of men or women was not influenced by the low stressor (P > 0.05). The greater fatigability, when exposed to a high stressor during a low-force task, was not exclusive to women but involved a strength-related mechanism in both weaker men and women that accelerated declines in voluntary activation and slowing of contractile properties.
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Affiliation(s)
- Manda L Keller-Ross
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
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Affiliation(s)
- Hugo M Pereira
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, USA
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Pereira LM, Obara K, Dias JM, Menacho MO, Guariglia DA, Schiavoni D, Pereira HM, Cardoso JR. Comparing the Pilates method with no exercise or lumbar stabilization for pain and functionality in patients with chronic low back pain: systematic review and meta-analysis. Clin Rehabil 2011; 26:10-20. [PMID: 21856719 DOI: 10.1177/0269215511411113] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To perform a systematic review with meta-analyses that evaluates the effectiveness of the Pilates method on the pain and functionality outcome in adults with non-specific chronic low back pain. DATA SOURCES The search was performed in the following databases: Medline, Embase, AMED, Cinahl, Lilacs, Scielo, SportDiscus, ProQuest, Web of Science, PEDro, Academic Search Premier and the Cochrane Central Register of Controlled Trials from 1950 to 2011; the following keywords were used: 'Pilates', 'Pilates-based', 'back exercises', 'exercise therapy', 'low back pain', 'back pain' and 'backache'. REVIEW METHODS The inclusion criteria were studies that assessed the effects of the Pilates method on patients with chronic low back pain. RESULTS Five studies met the inclusion criteria. The total number of patients was 71 in the Pilates group and 68 in the control group. Pilates exercise did not improve functionality (standardized mean difference (SMD = -1.34; 95% confidence interval (CI) -2.80, 0.11; P = 0.07) or pain between Pilates and control groups (SMD = -1.99; 95% CI -4.35, 0.37; P = 0.10). Pilates and lumbar stabilization exercises presented no significant difference in functionality (mean difference (MD) = -0.31; 95% CI -1.02, 0.40; P = 0.39) or pain (MD = -0.31; 95% CI -1.02, 0.40; P = 0.39). CONCLUSION The Pilates method did not improve functionality and pain in patients who have low back pain when compared with control and lumbar stabilization exercise groups.
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Affiliation(s)
- Ligia M Pereira
- MSc Programme in Physical Education, Universidade Estadual de Londrina-UEM, Londrina, Brazil
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Pereira HM, Nowotny AH, Santos ABAN, Cardoso JR. Electromyographic activity of knee stabilizer muscles during six different balance board stimuli after anterior cruciate ligament surgery. Electromyogr Clin Neurophysiol 2009; 49:117-124. [PMID: 19400407] [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] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The purpose of this study was to compare the electrical activity of the knee stabilizers, in patients with ACL (anterior cruciate ligament) reconstructed and uninjured individuals during different balance board stimuli. Eleven post-surgery individuals and eleven uninjured controls participated in the study. The muscular activity of the vastus medialis obliquus, vastus lateralis, semitendinosus, biceps femoris and gastrocnemius medial were analyzed by surface electromyography during the execution of six different balance board activities. All electromyographic data were reported as percentage of RMS mean values obtained in maximal voluntary isometric contractions (MVIC) for each muscle. When comparing the individuals with ACL reconstructed and uninjured controls, minor electromyographic activity was observed (MVIC %) for all the muscles in the surgery group (P < 0.05), however, when comparing each exercise between the groups, a statistically significant difference for vastus lateralis was demonstrated in the floor exercise (P = 0.02) and for gastrocnemius on the round board (P = 0.04). Individuals ACL reconstructed presented a decrease in muscular activity during different balance board stimuli, which suggests that compensatory alterations after ACL may still exist even after a surgery to repair an ACL rupture.
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Carvalho C, Pereira HM, Ferreira J, Pina C, Mendonça D, Rosa AC, Carmo-Fonseca M. Chromosomal G-dark bands determine the spatial organization of centromeric heterochromatin in the nucleus. Mol Biol Cell 2001; 12:3563-72. [PMID: 11694589 PMCID: PMC60276 DOI: 10.1091/mbc.12.11.3563] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [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: 11/11/2022] Open
Abstract
Gene expression can be silenced by proximity to heterochromatin blocks containing centromeric alpha-satellite DNA. This has been shown experimentally through cis-acting chromosome rearrangements resulting in linear genomic proximity, or through trans-acting changes resulting in intranuclear spatial proximity. Although it has long been been established that centromeres are nonrandomly distributed during interphase, little is known of what determines the three-dimensional organization of these silencing domains in the nucleus. Here, we propose a model that predicts the intranuclear positioning of centromeric heterochromatin for each individual chromosome. With the use of fluorescence in situ hybridization and confocal microscopy, we show that the distribution of centromeric alpha-satellite DNA in human lymphoid cells synchronized at G(0)/G(1) is unique for most individual chromosomes. Regression analysis reveals a tight correlation between nuclear distribution of centromeric alpha-satellite DNA and the presence of G-dark bands in the corresponding chromosome. Centromeres surrounded by G-dark bands are preferentially located at the nuclear periphery, whereas centromeres of chromosomes with a lower content of G-dark bands tend to be localized at the nucleolus. Consistent with the model, a t(11; 14) translocation that removes G-dark bands from chromosome 11 causes a repositioning of the centromere, which becomes less frequently localized at the nuclear periphery and more frequently associated with the nucleolus. The data suggest that "chromosomal environment" plays a key role in the intranuclear organization of centromeric heterochromatin. Our model further predicts that facultative heterochromatinization of distinct genomic regions may contribute to cell-type specific patterns of centromere localization.
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Affiliation(s)
- C Carvalho
- Instituto de Histologia e Embriologia, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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Abstract
Task allocation is the process that adjusts the number of workers in each colony task in response to the environment. There is no central coordination of task allocation; instead workers use local cues from the environment and from other workers to decide which task to perform. We examine two aspects of task allocation: the sensitivity to the environment of task distribution, and the rate of response to environmental changes. We investigate how these two aspects are influenced by: (1) colony size, and (2) behavioral rules used by workers, i.e. how a worker uses cues from the environment and from social interactions with other workers in deciding which task to perform. We show that if workers use social cues in their choice of task, response time decreases with increasing colony size. Sensitivity of task distribution to the environment may decrease or not with colony size, depending on the behavioral rules used by workers. This produces a trade-off in task allocation: short response times can be achieved by increasing colony size, but at the cost of decreased sensitivity to the environment. We show that when a worker's response to social interactions depends on the local environment, sensitivity of task distribution to the environment is not affected by colony size and the trade-off is avoided.
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Affiliation(s)
- H M Pereira
- Department of Biological Sciences, Stanford University, Stanford, CA, 94305-5020, USA.
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Abstract
In this report, we present a hypothesis on the mechanism used by interstitial collagenases to cleave their natural substrate, interstitial collagens. The hypothesis is based on the assumption that the proline hinge domain of interstitial collagenase adopts a collagen-like conformation. With a collagen-like domain, the enzyme is able to disturb the quaternary organization of the triple helix in the collagenase-susceptible site. A modeling analysis suggests that interaction between prolines of both collagen and collagenase forming a kind of "proline zipper" is involved in the destabilization step. This destabilization makes the three-collagen helix susceptible to the catalytic cleft of the catalytic core.
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Affiliation(s)
- S J De Souza
- Ludwig Institute for Cancer Research, Sao Paulo Branch, Brasil
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