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- Aging (17)
- Muscle fatigue (14)
- Sex differences (12)
- Gender (10)
- Physical activity (8)
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- Elbow flexor muscles (7)
- Exercise (7)
- Multiple sclerosis (7)
- Transcranial magnetic stimulation (7)
- Biomechanics (6)
- Walking (5)
- Central fatigue (4)
- Contractile properties (4)
- Electromyography (4)
- Force fluctuations (4)
- Stroke (4)
- Voluntary activation (4)
- Dynamic contractions (3)
- Electromyogram (3)
- Fatigue (3)
- Hip flexors (3)
- Injury (3)
- Isometric contractions (3)
- Neurological disease (3)
- Pressor response (3)
- Rehabilitation (3)
- Skeletal muscle (3)
- Strength (3)
- Stress (3)
- Women (3)
Articles 91 - 102 of 102
Full-Text Articles in Physical Therapy
Supraspinal Fatigue Does Not Explain The Sex Difference In Muscle Fatigue Of Maximal Contractions, Sandra K. Hunter, Jane E. Butler, Gabrielle Todd, Simon C. Gandevia, Janet L. Taylor
Supraspinal Fatigue Does Not Explain The Sex Difference In Muscle Fatigue Of Maximal Contractions, Sandra K. Hunter, Jane E. Butler, Gabrielle Todd, Simon C. Gandevia, Janet L. Taylor
Exercise Science Faculty Research and Publications
Young women are less fatigable than young men for maximal and submaximal contractions, but the contribution of supraspinal fatigue to the sex difference is not known. This study used cortical stimulation to compare the magnitude of supraspinal fatigue during sustained isometric maximal voluntary contractions (MVCs) performed with the elbow flexor muscles of young men and women. Eight women (25.6 ± 3.6 yr, mean ± SD) and 9 men (25.4 ± 3.8 yr) performed six sustained MVCs (22-s duration each, separated by 10 s). Before the fatiguing contractions, the men were stronger than the women (75.9 ± 9.2 vs. 42.7 ± …
Active Hyperemia And Vascular Conductance Differ Between Men And Women For An Isometric Fatiguing Contraction, Sandra K. Hunter, Jennie M. Schletty, Kristine M. Schlachter, Erin E. Griffith, Aaron J. Polichnowski, Alexander V. Ng
Active Hyperemia And Vascular Conductance Differ Between Men And Women For An Isometric Fatiguing Contraction, Sandra K. Hunter, Jennie M. Schletty, Kristine M. Schlachter, Erin E. Griffith, Aaron J. Polichnowski, Alexander V. Ng
Exercise Science Faculty Research and Publications
To understand the role of muscle perfusion in the sex differences of muscle fatigue, we compared the time to task failure, postcontraction (active) hyperemia, and vascular conductance for an isometric fatiguing contraction performed by young men and women with the handgrip muscles at 20% of maximal voluntary contraction (MVC) force. In study 1, the men (n = 16) were stronger than the women (n = 18), and study 2, the men (n = 7) and women (n = 7) were matched for strength. Isometric contractions were sustained during two sessions: 1) until the target …
Effects Of Sprint Training On Extrarenal Potassium Regulation With Intense Exercise In Type 1 Diabetes, Alison R. Harmer, Patricia A. Ruell, Michael J. Mckenna, Donald J. Chisholm, Sandra K. Hunter, Jeanette M. Thom, Norman R. Morris, Jeff R. Flack
Effects Of Sprint Training On Extrarenal Potassium Regulation With Intense Exercise In Type 1 Diabetes, Alison R. Harmer, Patricia A. Ruell, Michael J. Mckenna, Donald J. Chisholm, Sandra K. Hunter, Jeanette M. Thom, Norman R. Morris, Jeff R. Flack
Exercise Science Faculty Research and Publications
Effects of sprint training on plasma K+ concentration ([K+]) regulation during intense exercise and on muscle Na+-K+-ATPase were investigated in subjects with Type 1 diabetes mellitus (T1D) under real-life conditions and in nondiabetic subjects(CON). Eight subjects with T1D and seven CON undertook 7 wk of sprint cycling training. Before training, subjects cycled to exhaustion at 130% peak O2 uptake. After training, identical work was performed. Arterialized venous blood was drawn at rest, during exercise, and at recovery and analyzed for plasma glucose, [K+], Na+ concentration ([Na+]), catecholamines, …
Variability Of Motor Unit Discharge And Force Fluctuations Across A Range Of Muscle Forces In Older Adults, Brian L. Tracy, Katrina S. Maluf, Jennifer L. Stephenson, Sandra K. Hunter
Variability Of Motor Unit Discharge And Force Fluctuations Across A Range Of Muscle Forces In Older Adults, Brian L. Tracy, Katrina S. Maluf, Jennifer L. Stephenson, Sandra K. Hunter
Exercise Science Faculty Research and Publications
Variability of motor unit discharge is a likely contributor to the greater force fluctuations observed in old adults at low muscle forces. We sought to determine whether the variability of motor unit discharge rate underlies the fluctuations in force during steady contractions across a range of forces in young (n = 11) and old (n = 14) adults. The coefficient of variation (CV) for discharge rate and force were measured during a force-matching task as the first dorsal interosseous muscle performed isometric contractions. The recruitment thresholds of the 78 motor units ranged from 0.04% to 34% of maximal …
Muscle Endurance Is Greater For Old Men Compared With Strength-Matched Young Men, Sandra K. Hunter, Ashley Critchlow, Roger M. Enoka
Muscle Endurance Is Greater For Old Men Compared With Strength-Matched Young Men, Sandra K. Hunter, Ashley Critchlow, Roger M. Enoka
Exercise Science Faculty Research and Publications
The purpose was to compare the time to task failure for a sustained isometric contraction performed at a submaximal intensity with the elbow flexor muscles by young and old men who were matched for strength. Eight young men (18–31 yr) and eight old men (67–76 yr) sustained an isometric contraction at 20% of maximal voluntary contraction (MVC) torque until the target torque could no longer be achieved for at least 5 s. The maximal torque exerted at the wrist was similar for the young and old men before the fatiguing task (65.9 ± 8.0 vs. 65.4 ± 8.7 N·m; P …
Time To Task Failure Differs With Load Type When Old Adults Perform A Submaximal Fatiguing Contraction, Sandra K. Hunter, Ludovic Rochette, Ashley Critchlow, Roger M. Enoka
Time To Task Failure Differs With Load Type When Old Adults Perform A Submaximal Fatiguing Contraction, Sandra K. Hunter, Ludovic Rochette, Ashley Critchlow, Roger M. Enoka
Exercise Science Faculty Research and Publications
Young adults exhibit a longer time to task failure when performing a submaximal isometric contraction by pushing against a force transducer (force task) than when supporting an equivalent inertial load (position task). The purpose of this study was to compare the time to failure for old adults when they performed a force task and a position task with the elbow flexor muscles. Eighteen old adults (72 ± 4 years) performed the force and position tasks at 20% maximal voluntary contraction (MVC) force until task failure. The time to task failure was briefer for the position task (10.6 ± 6.1 min) …
Influence Of Aging On Sex Differences In Muscle Fatigability, Sandra K. Hunter, Ashley Critchlow, Roger M. Enoka
Influence Of Aging On Sex Differences In Muscle Fatigability, Sandra K. Hunter, Ashley Critchlow, Roger M. Enoka
Exercise Science Faculty Research and Publications
The purpose of this study was to compare time to task failure for a sustained isometric contraction performed at a submaximal intensity with elbow flexor muscles by young and old men and women. Twenty-seven young (14 men and 13 women, 18–35 yr) and 18 old (10 men and 8 women, 65–80 yr) adults sustained an isometric contraction at 20% of maximal voluntary contraction torque until target torque could no longer be achieved for ≥5 s. Young adults were stronger than old adults (66.8 ± 17.9 vs. 47.7 ± 18.1 N·m, P < 0.05), and men were stronger than women (69.8 ± 17.9 vs. 47.1 ± 15.3 N·m, P < 0.05), with no interaction between age and sex (P > 0.05). Time to task failure was longer …
Men Are More Fatigable Than Strength-Matched Women When Performing Intermittent Submaximal Contractions, Sandra K. Hunter, Ashley Critchlow, In-Sik Shin, Roger M. Enoka
Men Are More Fatigable Than Strength-Matched Women When Performing Intermittent Submaximal Contractions, Sandra K. Hunter, Ashley Critchlow, In-Sik Shin, Roger M. Enoka
Exercise Science Faculty Research and Publications
The purpose of this study was to compare the time to task failure for a series of intermittent submaximal contractions performed with the elbow flexor muscles by men and women who were matched for strength (n = 20, 18–34 yr). The fatigue task comprised isometric contractions at 50% of maximal voluntary contraction (MVC) torque (6-s contraction, 4-s rest). The MVC torque was similar for the men and women [64.8 ± 9.2 (SD) vs. 62.2 ± 7.9 N·m; P > 0.05]. However, the time to task failure was longer for the women (1,408 ± 1,133 vs. 513 ± 194 s; P …
Muscle Fatigue And The Mechanisms For Task Failure, Sandra K. Hunter, Jacques Duchateau, Roger M. Enoka
Muscle Fatigue And The Mechanisms For Task Failure, Sandra K. Hunter, Jacques Duchateau, Roger M. Enoka
Exercise Science Faculty Research and Publications
An alternative approach in the study of muscle fatigue is to address the question, “What causes task failure during a fatiguing contraction?” This approach is described by considering how variation in the type of load supported and contraction intensity influence both the time to task failure and the centrally mediated adjustments in reflex activity and motor unit behavior
Fatigability Of The Elbow Flexor Muscles For A Sustained Submaximal Contraction Is Similar In Men And Women Matched For Strength, Sandra K. Hunter, Ashley Critchlow, In-Sik Shin, Roger M. Enoka
Fatigability Of The Elbow Flexor Muscles For A Sustained Submaximal Contraction Is Similar In Men And Women Matched For Strength, Sandra K. Hunter, Ashley Critchlow, In-Sik Shin, Roger M. Enoka
Exercise Science Faculty Research and Publications
The purpose of this study was to compare the time to task failure for a submaximal fatiguing contraction sustained with the elbow flexor muscles by men and women who were matched for strength (n = 20, 18-35 yr). The maximal torque exerted at the wrist was similar for the men and women [64.5 ± 8.7 (SD) vs. 64.5 ± 8.3 N·m; P > 0.05], which meant that the average torque exerted during the fatiguing contraction [20% of maximum voluntary contraction (MVC)] was similar for the two sexes. The time to task failure was similar for these strength-matched men and women …
Ventilatory Phenotypes Among Four Strains Of Adult Rats., Matthew Hodges, Hubert Forster, Paula E. Papanek, Melinda R. Dwinell, Genevieve E. Hogan
Ventilatory Phenotypes Among Four Strains Of Adult Rats., Matthew Hodges, Hubert Forster, Paula E. Papanek, Melinda R. Dwinell, Genevieve E. Hogan
Exercise Science Faculty Research and Publications
Our purpose in this study was to identify different ventilatory phenotypes among four different strains of rats. We examined 114 rats from three in-house, inbred strains and one outbred strain: Brown Norway (BN;n = 26), Dahl salt-sensitive (n = 24), Fawn-hooded Hypertensive (FHH: n = 27), and outbred Sprague-Dawley rats (SD; n = 37). We measured eupneic (room air) breathing and the ventilatory responses to hypoxia (12% O2-88% N2), hypercapnia (7% CO2), and two levels of submaximal exercise. Primary strain differences were between BN and the other strains. BN rats had a …
Angiotensin Ii And Vegf Are Involved In Angiogenesis Induced By Short-Term Exercise Training, Sandra L. Amaral, Paula E. Papanek, Andrew S. Greene
Angiotensin Ii And Vegf Are Involved In Angiogenesis Induced By Short-Term Exercise Training, Sandra L. Amaral, Paula E. Papanek, Andrew S. Greene
Exercise Science Faculty Research and Publications
Results from our laboratory have suggested a pathway involving angiotensin II type 1 (AT1) receptors and vascular endothelial growth factor (VEGF) in angiogenesis induced by electrical stimulation. The present study investigated if similar mechanisms underlie the angiogenesis induced by short-term exercise training. Seven days before training and throughout the training period, male Sprague-Dawley rats received either captopril or losartan in their drinking water. Rats underwent a 3-day treadmill training protocol. The tibialis anterior and gastrocnemius muscles were harvested under anesthesia and lightly fixed in formalin (vessel density) or frozen in liquid nitrogen (VEGF expression). In controls, treadmill training …