Physical Therapy Commons^™

Sex Differences In Neuromuscular Fatigability Of The Knee Extensors Post-Stroke, Meghan Kirking, Reivian B. Barillas, Philip A. Nelson, Sandra K. Hunter, Allison S. Hyngstrom

Exercise Science Faculty Research and Publications

Background and Purpose: Despite the implications of optimizing strength training post-stroke, little is known about the differences in fatigability between men and women with chronic stroke. The purpose of this study was to determine the sex differences in knee extensor muscle fatigability and potential mechanisms in individuals with stroke. Methods: Eighteen participants (10 men, eight women) with chronic stroke (≥6 months) and 23 (12 men, 11 women) nonstroke controls participated in the study. Participants performed an intermittent isometric contraction task (6 s contraction, 3 s rest) at 30% of maximal voluntary contraction (MVC) torque until failure to maintain the target …

Muscle Function And Fatigability Of Trunk Flexors In Males And Females, Rita Deering, Jonathon Senefeld, Tatyana Pashibin, Donald A. Neumann, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Background

Optimal function of the abdominal muscles is necessary for several life functions including lifting and carrying tasks. Sex differences in strength and fatigability are established for many limb muscles and back extensor muscles, but it is unknown if sex differences exist for the abdominal muscles despite their functional importance.

Methods

Eighteen females (24.3 ± 4.8 years) and 15 males (24.1 ± 6.6 years) performed (1) isometric trunk flexion maximal voluntary contractions (MVCs) in a range of trunk positions to establish a torque-angle curve and (2) submaximal (50% MVC), intermittent isometric contraction (6 s on, 4 s off) until task …

Sex Differences In Elite Swimming With Advanced Age Are Less Than Marathon Running, Jonathon Senefeld, Michael J. Joyner, A. Stevens, Sandra K. Hunter

Exercise Science Faculty Research and Publications

The sex difference in marathon performance increases with finishing place and age of the runner but whether this occurs among swimmers is unknown. The purpose was to compare sex differences in swimming velocity across world record place (1st–10th), age group (25–89 years), and event distance. We also compared sex differences between freestyle swimming and marathon running. The world's top 10 swimming times of both sexes for World Championship freestyle stroke, backstroke, breaststroke, and butterfly events and the world's top 10 marathon times in 5-year age groups were obtained. Men were faster than women for freestyle (12.4 ± 4.2%), backstroke (12.8 …

Impaired Hyperemic Response To Exercise Post Stroke, Matthew J. Durand, Spencer A. Murphy, Kathleen K. Schaefer, Sandra K. Hunter, Brian D. Schmit, David D. Gutterman, Allison S. Hyngstrom

Exercise Science Faculty Research and Publications

Individuals with chronic stroke have reduced perfusion of the paretic lower limb at rest; however, the hyperemic response to graded muscle contractions in this patient population has not been examined. This study quantified blood flow to the paretic and non-paretic lower limbs of subjects with chronic stroke after submaximal contractions of the knee extensor muscles and correlated those measures with limb function and activity. Ten subjects with chronic stroke and ten controls had blood flow through the superficial femoral artery quantified with ultrasonography before and immediately after 10 second contractions of the knee extensor muscles at 20, 40, 60, and …

Spinal And Supraspinal Motor Control Predictors Of Rate Of Torque Development, S. T. Johnson, Kristof Kipp, M. F. Norcross, M. A. Hoffman

Exercise Science Faculty Research and Publications

During explosive movements and potentially injurious situations, the ability to rapidly generate torque is critical. Previous research has suggested that different phases of rate of torque development (RTD) are differentiately controlled. However, the extent to which supraspinal and spinal mechanisms predict RTD at different time intervals is unknown. RTD of the plantarflexors across various phases of contraction (i.e., 0–25, 0–50, 0–100, 0–150, 0–200, and 0–250 ms) was measured in 37 participants. The following predictor variables were also measured: (a) gain of the resting soleus H-reflex recruitment curve; (b) gain of the resting homonymous post-activation depression recruitment curve; (c) gain of …

Age And Sex Differences In Steadiness Of Elbow Flexor Muscles With Imposed Cognitive Demand, Hugo M. Pereira, Vincent C. Spears, Bonnie Schlinder-Delap, Tejin Yoon, Kristy A. Nielson, Sandra K. Hunter

Exercise Science Faculty Research and Publications

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 …

Stroke-Related Effects On Maximal Dynamic Hip Flexor Fatigability And Functional Implications, Henry Kuhnen, Megan M. Rybar, Tanya Onushko, Ryan E. Doyel, Sandra K. Hunter, Brian D. Schmit, Allison S. Hyngstrom

Exercise Science Faculty Research and Publications

Introduction: Stroke-related changes in maximal dynamic hip flexor muscle fatigability may be more relevant functionally than isometric hip flexor fatigability. Methods: Ten chronic stroke survivors performed 5 sets of 30 hip flexion maximal dynamic voluntary contractions (MDVC). A maximal isometric voluntary contraction (MIVC) was performed before and after completion of the dynamic contractions. Both the paretic and nonparetic legs were tested. Results: Reduction in hip flexion MDVC torque in the paretic leg (44.7%) was larger than the nonparetic leg (31.7%). The paretic leg had a larger reduction in rectus femoris EMG (28.9%) between the first and last …

Use Of Audio Biofeedback To Reduce Tibial Impact Accelerations During Running, Claire M. Wood, Kristof Kipp

Exercise Science Faculty Research and Publications

Visual biofeedback of tibial peak positive acceleration (PPA) during running has been used successfully as a method of gait retraining to reduce PPAs. Audio biofeedback generated from PPA may present a novel, portable alternative. The purpose of this study was to investigate the feasibility of using PPA-generated audio biofeedback to reduce PPAs while running. Nine runners were fitted with a wireless accelerometer on their left tibia. PPAs were recorded and a custom LabVIEW program was used to emit a single beep once the PPA reached a preset threshold. The numerical difference between this threshold and peak PPA during running was …

The Stroke-Related Effects Of Hip Flexion Fatigue On Over Ground Walking, Megan M. Rybar, Eric R. Walker, Henry Kuhnen, Daniel R. Ouellette, Reivian Berrios, Sandra K. Hunter, Allison S. Hyngstrom

Exercise Science Faculty Research and Publications

Individuals post stroke often rely more on hip flexors for limb advancement during walking due to distal weakness but the effects of muscle fatigue in this group is not known. The purpose of this study was to quantify how stroke affects the influence of hip flexor fatigue on over ground walking kinematics and performance and muscle activation. Ten individuals with chronic stroke and 10 without stroke (controls) participated in the study. Maximal walking speed, walking distance, muscle electromyograms (EMG), and lower extremity joint kinematics were compared before and after dynamic, submaximal fatiguing contractions of the hip flexors (30% maximal load) …

Fatigue And Recovery From Dynamic Contractions In Men And Women Differ For Arm And Leg Muscles, Jonathon Senefeld, Tejin Yoon, Marie K. Hoeger Bement, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Introduction: Whether there is a gender difference in fatigue and recovery from maximal velocity fatiguing contractions and across muscles is not understood. Methods: Sixteen men and 19 women performed 90 isotonic contractions at maximal voluntary shortening velocity (maximal velocity concentric contractions, MVCC) with the elbow flexor and knee extensor muscles (separate days) at a load equivalent to 20% maximal voluntary isometric contraction (MVIC). Results: Power (from MVCCs) decreased similarly for men and women for both muscles (P > 0.05). Men and women had similar declines in MVIC of elbow flexors, but men had greater reductions in knee extensor MVIC force and …

Functional Implications Of Impaired Control Of Submaximal Hip Flexion Following Stroke, Allison S. Hyngstrom, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Introduction: We quantified sub-maximal torque regulation during low to moderate intensity isometric hip flexion contractions in individuals with stroke and the associations with leg function. Methods: 10 participants with chronic stroke and 10 controls performed isometric hip flexion contractions at 5%, 10%, 15%, 20%, and 40% of maximal voluntary contraction (MVC) in paretic, non-paretic, and control legs. Results: Participants with stroke had larger torque fluctuations (coefficient of variation, CV), for both the paretic and non-paretic legs, than controls (Pr² =0.45) and Berg Balance Score (r²=0.38). At 5% MVC, there were larger torque fluctuations in the …

Near Infrared Spectroscopic Monitoring During Cardiopulmonary Exercise Testing Detects Anaerobic Threshold, Rohit P. Rao, Michael J. Danduran, J. E. Dixon, Rohit S. Loomba, George M. Hoffman

Exercise Science Faculty Research and Publications

Cardiopulmonary exercise testing (CPET) provides assessment of the integrative responses involving the pulmonary, cardiovascular, and skeletal muscle systems. Application of exercise testing remains limited to children who are able to understand and cooperate with the exercise protocol. Near-infrared spectroscopy (NIRS) provides a noninvasive, continuous method to monitor regional tissue oxygenation (rSO2). Our specific aim was to predict anaerobic threshold (AT) during CPET noninvasively using two-site NIRS monitoring. Achievement of a practical noninvasive technology for estimating AT will increase the compatibility of CPET. Patients without structural or acquired heart disease were eligible for inclusion if they were ordered to undergo CPET …

Supraspinal Fatigue Impedes Recovery From A Low-Intensity Sustained Contraction In Old Adults, Tejin Yoon, Bonnie Schlinder-Delap, Manda L. Keller, Sandra K. Hunter

Exercise Science Faculty Research and Publications

This study determined the contribution of supraspinal fatigue and contractile properties to the age difference in neuromuscular fatigue during and recovery from a low-intensity sustained contraction. Cortical stimulation was used to evoke measures of voluntary activation and muscle relaxation during and after a contraction sustained at 20% of maximal voluntary contraction (MVC) until task failure with elbow flexor muscles in 14 young adults (20.9 ± 3.6 yr, 7 men) and 14 old adults (71.6 ± 5.4 yr, 7 men). Old adults exhibited a longer time to task failure than the young adults (23.8 ± 9.0 vs. 11.5 ± 3.9 min, …

Near Infrared Spectroscopy Describes Physiologic Payback Associated With Excess Postexercise Oxygen Consumption In Healthy Controls And Children With Complex Congenital Heart Disease, Michael J. Danduran, J. E. Dixon, Rohit P. Rao

Exercise Science Faculty Research and Publications

Exercise creates a physiologic burden with recovery from such effort crucial to adaptation. Excess postexercise oxygen consumption (EPOC) refers to the body’s increased metabolic need after work. This investigation was designed to determine the role of near infrared spectroscopy (NIRS) in the description of exercise recovery in healthy controls (NL) and children with congenital heart disease (CHD). Subjects were recruited with exercise testing performed to exhaustion. Exercise time (EXT), heart rate (HR), and oxygen consumption (VO₂) were measured. Four-site NIRS (brain, kidney, deltoid, and vastus lateralis) were measured during exercise and into recovery to establish trends. Fifty individuals …

Association Between The Female Athlete Triad And Endothelial Dysfunction In Dancers, Anne Z. Hoch, Paula E. Papanek, Aniko Szabo, Michael E. Widlansky, Jane E. Schimke, David D. Gutterman

Exercise Science Faculty Research and Publications

Objective: To determine the prevalence of the 3 components of the female athlete triad [disordered eating, menstrual dysfunction, low bone mineral density (BMD)] and their relationships with brachial artery flow-mediated dilation in professional dancers.

Design: Prospective study.

Setting: Academic institution in the Midwest.

Participants: Twenty-two professional ballet dancers volunteered for this study.

Interventions: The prevalence of the female athlete triad and its relationship to endothelial dysfunction.

Main Outcome Measures: Subjects completed questionnaires to assess disordered eating and menstrual status/history. They also completed a 3-day food record and wore an accelerometer for 3 days to …

Pain Perception After Isometric Exercise In Women With Fibromyalgia, Marie K. Hoeger Bement, Andy Weyer, Sarah Hartley, Breanna Drewek, April L. Harkins, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Objective: The purpose of this study was to identify exercise protocols incorporating isometric contractions that provide pain relief in women with fibromyalgia.

Design: A before-after trial.

Setting: A physical therapy department in an academic setting.

Participants: Fifteen women (mean ± SD, 52 ± 11y) with fibromyalgia.

Interventions: Subjects completed 4 sessions: 1 familiarization and 3 experimental. The following randomized experimental sessions involved the performance of isometric contractions with the elbow flexor muscles that varied in intensity and duration: (1) 3 maximal voluntary contractions (MVCs), (2) 25% MVC held to task failure, and (3) 25% MVC …

Resilient Observer Design For Discrete-Time Nonlinear Systems With General Criteria, Chung Seop Jeong, Edwin E. Yaz, Yvonne I. Yaz

Exercise Science Faculty Research and Publications

A class of discrete-time nonlinear system and measurement equations having incrementally conic nonlinearities and finite energy disturbances is considered. A linear matrix inequality based resilient observer design approach is presented to guarantee the satisfaction of a variety of performance criteria ranging from simple estimation error boundedness to dissipativity in the presence of bounded perturbations on the gain. Some simulation examples are included to illustrate the proposed design methodology.

The Underrecognized Role Of Impaired Muscle Function In Cancer-Related Fatigue, Alexander V. Ng

Exercise Science Faculty Research and Publications

No abstract provided.

Age And Load Compliance Alter Time To Task Failure For A Submaximal Fatiguing Contraction With The Lower Leg, Erin E. Griffith, Tejin Yoon, Sandra K. Hunter

Exercise Science Faculty Research and Publications

The purpose of this study was to compare the time to failure and muscle activation of young and old adults for a sustained isometric submaximal contraction with the dorsiflexor muscles when the foot was restrained to a force transducer (force-control task) compared with supporting an equivalent inertial load unrestrained in the sagittal plane (position-control task). Seventeen young (23.6 ± 6.5 yr) and 12 old (70.0 ± 5.0 yr) adults performed the force-control and position-control tasks at 30% maximal voluntary contraction (MVC) until task failure on separate days. Despite the similar load torque for each task, time to failure was longer …

Reliability Of Surface Electromyography During Maximal Voluntary Isometric Contractions, Jump Landings, And Cutting, Mckenzie Fauth, Erich Petushek, Christina Feldmann, Brittni Hsu, Luke Garceau, Brittney Lutsch, William Ebben

Exercise Science Faculty Research and Publications

The reliability of electromyographic (EMG) data has been examined for isometric and slow dynamic tasks, but little is known about the repeatability of this data for ballistic movements. The purpose of this study was to examine the within-session, trial-to-trial reliability of a variety of quadriceps and hamstrings muscles during isometric and ballistic activities. Data were analyzed by way of intraclass correlation coefficients (ICC), intersubject coefficients of variation (CV_inter), and intrasubject coefficients of variation (CV_intra). Twenty-four subjects performed 3 repetitions each of 2 randomly ordered test exercises, including landing from a depth jump (J) and cutting after …

Gender-Based Analysis Of Hamstring And Quadriceps Muscle Activation During Jump Landings And Cutting, William Ebben, Mckenzie Fauth, Erich Petushek, Luke Garceau, Brittni Hsu, Brittney Lutsch, Christina Feldmann

Exercise Science Faculty Research and Publications

This study evaluated gender differences in the magnitude and timing of hamstring and quadriceps activation during activities that are believed to cause anterior cruciate ligament (ACL) injuries. Twelve men (age = 21.0 ± 1.2 years; body mass = 81.61 ± 13.3 kg; and jump height = 57.61 ± 10.15 cm) and 12 women (age = 19.91 ± 0.9 years; body mass = 64.36 ± 6.14 kg; and jump height = 43.28 ± 7.5) performed 3 repetitions each of the drop jump (jump) normalized to the subject's vertical jump height, and a sprint and cut at a 45-degree angle (cut). Electromyography …

Response To Task-Specific Sex Differences In Muscle Fatigue: Is There A Common Underlying Cause?, Sandra K. Hunter

Exercise Science Faculty Research and Publications

No abstract provided.

Sex Differences In Response To Cognitive Stress During A Fatiguing Contraction, Tejin Yoon, Manda Linea Keller, Bonnie Schlinder-Delap, April L. Harkins, Romuald Lepers, Sandra K. Hunter

Exercise Science Faculty Research and Publications

This study compared the time to task failure for a submaximal fatiguing contraction in the presence and absence of a cognitive stressor in men and women. In study 1, 10 men and 10 women (22 ± 3 yr of age) performed an isometric fatiguing contraction at 20% maximal voluntary contraction force until task failure with the elbow flexor muscles during two separate sessions. Subjects performed a mental-math task during one of the fatiguing contractions that aimed to increase anxiety and stress (stressor session). Salivary cortisol and reported levels of arousal (visual analog scale for anxiety, and State-Trait Anxiety Inventory …

Sex Differences And Mechanisms Of Task-Specific Muscle Fatigue, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Women can be less fatigable than men due to sex-related differences within the neuromuscular system that impact physiological adjustments during a fatiguing task. The involved mechanism(s) for the sex difference, however, is task specific. This review explores the novel hypothesis that variation of the task will alter the magnitude of the sex-difference in muscle fatigue and the contribution of involved mechanisms.

Sex Differences In Time To Task Failure And Blood Flow For An Intermittent Isometric Fatiguing Contraction, Sandra K. Hunter, Erin E. Griffith, Kristine M. Schlachter, Tim D. Kufahl

Exercise Science Faculty Research and Publications

The purpose of this study was to compare the time to task failure, postcontraction hyperemia, and vascular conductance of young men and women for a submaximal intermittent fatiguing contraction performed with the handgrip muscles. Twenty men and 20 women (mean SD: 22 4 years) performed an isometric contraction at 50% of maximal voluntary contraction (MVC) (6-s contraction, 4-s rest) until task failure. Forearm venous occlusion plethysmography was used to estimate the peak blood flow (after 10-min occlusion) and blood flow at rest after 6-s submaximal contractions of varying intensities, and during an intermittent fatiguing contraction at 1-min intervals and task …

Recovery From Supraspinal Fatigue Is Slowed In Old Adults After Fatiguing Maximal Isometric Contractions, Sandra K. Hunter, Gabrielle Todd, Jane E. Butler, Simon C. Gandevia, Janet L. Taylor

Exercise Science Faculty Research and Publications

This study compared the contribution of supraspinal fatigue to muscle fatigue in old and young adults. Transcranial magnetic stimulation (TMS) of motor cortex was used to assess voluntary activation during maximal voluntary contractions (MVCs) of elbow flexor muscles in 17 young adults (25.5 ± 3.6 yr; mean ± SD) and 7 old adults (73.0 ± 3.3 yr). Subjects performed a fatigue task involving six sustained MVCs (22-s duration, separated by 10 s). Young adults exhibited greater reductions in maximal voluntary torque (67 ± 15% of baseline) than the old (37 ± 6%; P < 0.001). Increments in torque (superimposed twitch) generated by TMS during sustained MVCs increased for the young and old(P < 0.001) but were larger for the old adults at the start of the sustained contractions and during recovery (P < 0.05). Voluntary activation was less for the old adults at the start of some sustained contractions and during recovery(P = 0.02). Motor-evoked potential …

Time To Task Failure And Muscle Activation Vary With Load Type For A Submaximal Fatiguing Contraction With The Lower Leg, Sandra K. Hunter, Tejin Yoon, Joseph Farinella, Erin E. Griffith, Alexander V. Ng

Exercise Science Faculty Research and Publications

The purpose was to compare the time to failure and muscle activation patterns for a sustained isometric submaximal contraction with the dorsiflexor muscles when the foot was restrained to a force transducer (force task) compared with supporting an equivalent inertial load and unrestrained (position task). Fifteen men and women (mean ± SD; 21.1 ± 1.4 yr) performed the force and position tasks at 20% maximal voluntary contraction force until task failure. Maximal voluntary contraction force performed before the force and position tasks was similar (333 ± 71 vs. 334 ± 65 N), but the time to task failure was briefer …

Mechanisms Of Fatigue Differ After Low- And High-Force Fatiguing Contractions In Men And Women, Tejin Yoon, Bonnie A. Schlinder-Delap, Erin E. Griffith, Sandra K. Hunter

Exercise Science Faculty Research and Publications

The magnitude of failure in voluntary drive after fatiguing contractions of different intensities in men and women is not known. The purpose of this study was to compare the time to task failure and voluntary activation of men and women for a sustained isometric contraction performed at a low and high intensity with the elbow flexor muscles. Nine men and nine women sustained an isometric contraction at 20% and 80% of maximal voluntary contraction (MVC) force until task failure during separate sessions. The men had a shorter time to failure than women for the 20% but not the 80% MVC …

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

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 …