Recreational Therapy Commons^™

The Relationship Between Blood Flow And Motor Unit Firing Rates In Response To Fatiguing Exercise Post-Stroke, Spencer Murphy, Matthew J. Durand, Francesco Negro, Dario Farina, Sandra K. Hunter, Brian D. Schmit, David D. Gutterman, Allison S. Hyngstrom

Exercise Science Faculty Research and Publications

We quantified the relationship between the change in post-contraction blood flow with motor unit firing rates and metrics of fatigue during intermittent, sub-maximal fatiguing contractions of the knee extensor muscles after stroke. Ten chronic stroke survivors (>1-year post-stroke) and nine controls participated. Throughout fatiguing contractions, the discharge timings of individual motor units were identified by decomposition of high-density surface EMG signals. After five consecutive contractions, a blood flow measurement through the femoral artery was obtained using an ultrasound machine and probe designed for vascular measurements. There was a greater increase of motor unit firing rates from the beginning of …

Oscillations In Neural Drive And Age-Related Reductions In Force Steadiness With A Cognitive Challenge, Hugo M. Pereira, Bonnie A. Schlinder-Delap Mrs., Kevin G. Keenan, Francesco Negro, Dario Farina, Allison S. Hyngstrom, Kristy A. Nielson, Sandra K. Hunter

Exercise Science Faculty Research and Publications

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 …

Ballroom Dance For Persons With Multiple Sclerosis: A Pilot Feasibility Study, Alexander V. Ng, Sheri Bunyan, Jimin Suh, Pamela Huenink, Tyler Gregory, Shannon Gambon, Deborah Miller

Exercise Science Faculty Research and Publications

Purpose: The purpose of this study was to evaluate the exercise intensity and feasibility of recreational ballroom dance for persons with multiple sclerosis (MS).

Methods: Seven persons with MS participated in 2 one-hour dance sessions per week for 6 weeks. Dance types included rumba, foxtrot, waltz, and push-pull. Six other persons with MS comprised a control group that did not dance. Heart rate and ratings of perceived exertion (RPE) were monitored during the sessions. Outcomes included: quality of life, fatigue, depression, self-efficacy, timed up and go, Berg Balance Scale, Dynamic Gait Index and the Multiple Sclerosis Functional Composite comprising 9-hole …

A Substruction Approach To Assessing The Theoretical Validity Of Measures, Polly Ryan, Marianne E. Weiss, Paula E. Papanek

Exercise Science Faculty Research and Publications

Background

Validity is about the logic, meaningfulness, and evidence used to defend inferences made when interpreting results. Substruction is a heuristic or process that visually represent the hierarchical structure between theory and measures.

Purpose

To describe substruction as a method for assessing the toretical validity of research measures.

Methods

Using Fawcett's Conceptual-Theoretical-Empirical Structure. an exemplar is presented of substruction from the Individual and Family Self-Management Theory to the Striving to be strong study concepts and empirical measures.

Results

Substruction tables display evidence supporting theoretical validity of the instruments used in the study.

Conclusion

A high degree of congruence between theory …

Force Steadiness During A Cognitively Challenging Motor Task Is Predicted By Executive Function In Older Adults, Hugo M. Pereira, Bonnie A. Schlinder-Delap Mrs., Kristy A. Nielson, Sandra K. Hunter

Exercise Science Faculty Research and Publications

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 …

Home-Based, Square-Stepping Exercise Program Among Older Adults With Multiple Sclerosis: Results Of A Feasibility Randomized Controlled Study, Emerson Sebastião, Edward Mcauley, Ryosuke Shigematsu, Brynn C. Adamson, Rachel E. Bollaert, Robert W. Motl

Exercise Science Faculty Research and Publications

There is very little known about exercise rehabilitation approaches for older adults with multiple sclerosis (MS), yet this growing segment of the MS population experiences declines in cognition and mobility associated with disease progression and aging. We conducted a RCT examining the feasibility of a 12-week, home-based Square-Stepping Exercise (SSE) program in older adults with MS. Older adults with MS (N = 26) with mild-to-moderate levels of disability were recruited and randomized into the intervention (i.e., SSE) or a minimal activity, attention-control conditions. Participants in the SSE condition received a mat for home-based practice of the step patterns, an …

Gait Variability And Energy Cost Of Overground Walking In Persons With Multiple Sclerosis: A Cross-Sectional Study, Emerson Sebastião, Rachel E. Bollaert, Elizabeth A. Hubbard, Robert W. Motl

Exercise Science Faculty Research and Publications

Objective: This study examined the associations between gait variability based on common spatiotemporal parameters and energetic cost of walking in persons with multiple sclerosis.

Design: Eighty-six persons with multiple sclerosis underwent the 6-min walk while wearing a portable metabolic unit. The cost of walking was generated by dividing the net steady-state VO₂ (milliliter per kilogram per minute) by walking speed during the 6-min walk. Participants further completed two trials of walking on the GAITRite mat at a self-selected pace for measuring spatiotemporal parameters. Variability of step length, step time, stride length, swing time, stance time, stride velocity, and single- …

Associations Of Functional Connectivity And Walking Performance In Multiple Sclerosis, Rachel E. Bollaert, Kyle Poe, Elizabeth A. Hubbard, Robert W. Motl, Lara A. Pilutti, Curtis L. Johnson, Bradley P. Sutton

Exercise Science Faculty Research and Publications

Background

Persons with multiple sclerosis (MS) often demonstrate impaired walking performance, and neuroimaging methods such as resting state functional connectivity. (RSFC) may support a link between central nervous system damage and disruptions in walking.

Objectives

This study examined associations between RSFC in cortical networks and walking performance in persons with MS.

Methods

29 persons with MS underwent 3-T brain magnetic resonance imaging (MRI) and we computed RSFC among 68 Gy matter regions of interest in the brain. Participants completed the Timed 25-foot Walk as a measure of walking performance. We examined associations using partial Pearson product-moment correlation analyses (r …

Mechanisms For The Increased Fatigability Of The Lower Limb In People With Type 2 Diabetes, Jonathon Senefeld, Steven B. Magill, April L. Harkins, Alison R. Harmer, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Fatiguing exercise is the basis of exercise training and a cornerstone of management of type 2 diabetes mellitus (T2D), however, little is known about the fatigability of limb muscles and the involved mechanisms in people with T2D. The purpose was to compare fatigability of knee extensor muscles between people with T2D and controls without diabetes and determine the neural and muscular mechanisms for a dynamic fatiguing task. Seventeen people with T2D (10 men, 7 women: 59.6{plus minus}9.0 years) and 21 age-, BMI- and physical activity-matched controls (11 men, 10 women: 59.5{plus minus}9.6 years) performed 120 high-velocity concentric contractions (1 contraction/3 …

Physical Activity And Annual Medical Outlay In U.S. Colorectal, Breast And Prostate Cancer Survivors, Alice F. Yan, Yang Wang, Alexander V. Ng

Exercise Science Faculty Research and Publications

Multiple chronic conditions in cancer survivors are highly prevalent and may increase health care costs for both patients and the health care system. Studies of cancer survivors reveal positive effects of physical activity (PA) on reducing risk of cancer recurrence, other chronic conditions, and secondary cancer. Few nationally representative studies have examined how physical activity levels have affected survivors' annual economic burden in the United States.

Leisure-time physical activity data from the National Health Interview Survey was linked to health care expenditure data from the Medical Expenditure Panel Survey data (2008–2012). We calculated per-person annual total medical expenditures for identified …

Six-Minute Walk Test Performance In Persons With Multiple Sclerosis While Using Passive Or Powered Ankle-Foot Orthoses, Morgan K. Boes, Rachel E. Bollaert, Richard M. Kesler, Yvonne C. Learmonth, Mazharul Islam, Matthew N. Petrucci, Robert W. Motl, Elizabeth T. Hsiao-Wecksler

Exercise Science Faculty Research and Publications

Objective

To determine whether a powered ankle-foot orthosis (AFO) that provides dorsiflexor and plantar flexor assistance at the ankle can improve walking endurance of persons with multiple sclerosis (MS).

Design

Short-term intervention.

Setting

University research laboratory.

Participants

Participants (N=16) with a neurologist-confirmed diagnosis of MS and daily use of a prescribed custom unilateral passive AFO.

Interventions

Three 6-minute walk tests (6MWTs), 1 per footwear condition: shoes (no AFO), prescribed passive AFO, and portable powered AFO (PPAFO). Assistive devices were worn on the impaired limb.

Main Outcome Measures

Distance walked and metabolic cost of transport were recorded during each 6MWT and …

Validation Of The Godin Leisure-Time Exercise Questionnaire Classification Coding System Using Accelerometry In Multiple Sclerosis, Robert W. Motl, Rachel E. Bollaert, Brian M. Sandroff

Exercise Science Faculty Research and Publications

Objective: There have been recent efforts toward creating a health contribution score (HCS) from the Godin Leisure-Time Exercise Questionnaire (GLTEQ) that reflects public-health guidelines for levels of moderate-to-vigorous physical activity (MVPA). The HCS yields categories of insufficiently active (less substantial or low benefits), moderately active (some benefits), and active (substantial benefits). The present study examined the validity of the GLTEQ HCS and its categories as reflecting levels of MVPA in multiple sclerosis (MS). Method: The sample included 684 persons with MS. Participants wore an accelerometer on an elastic belt around the waist above the nondominant hip during the waking hours …

Girls In The Boat: Sex Differences In Rowing Performance And Participation, Kevin G. Keenan, Jonathon Senefeld, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Men outperform women in many athletic endeavors due to physiological and anatomical differences (e.g. larger and faster muscle); however, the observed sex differences in elite athletic performance are typically larger than expected, and may reflect sex-related differences in opportunity or incentives. As collegiate rowing in the United States has been largely incentivized for women over the last 20 years, but not men, the purpose of this study was to examine sex differences in elite rowing performance over that timeframe. Finishing times from grand finale races for collegiate championship on-water performances (n = 480) and junior indoor performances (n = 1,280) …

Contraction Intensity And Sex Differences In Knee-Extensor Fatigability, Paul Ansdell, Kevin Thomas, Glyn Howatson, Sandra K. Hunter, Stuart Goodall

Exercise Science Faculty Research and Publications

Females are less fatigable than males during isometric contractions across various muscles and intensities. However, sex differences in knee-extensor fatigability remain relatively unexplored. Purpose: To determine the sex difference in performance fatigability for intermittent, isometric contractions of the knee-extensor muscles. Methods: Eighteen participants (10 males, 8 females) performed intermittent, isometric, knee-extensor contractions at 30% of their maximal voluntary force (MVC) for 30 min and in a separate session at 50% MVC until task-failure. During both fatiguing protocols a MVC was performed every 60 s and electromyography (EMG) was recorded during all contractions. Results: At task completion males had a larger …

Physiological Response To Firefighting Activities Of Various Work Cycles Using Extended Duration And Prototype Scba, Richard M. Kesler, Ipek Ensari, Rachel E. Bollaert, Robert W. Motl, Elizabeth T. Hsiao-Wecksler, Karl S. Rosengren, Bo Fernhall, Denise L. Smith, Gavin P. Horn

Exercise Science Faculty Research and Publications

Firefighters’ self-contained breathing apparatus (SCBA) protects the respiratory system during firefighting but increases the physiological burden. Extended duration SCBA (>30 min) have increased air supply, potentially increasing the duration of firefighting work cycles. To examine the effects of SCBA configuration and work cycle (length and rest), 30 firefighters completed seven trials using different SCBA and one or two bouts of simulated firefighting following work cycles common in the United States. Heart rate, core temperature, oxygen consumption, work output and self-reported perceptions were recorded during all activities. Varying SCBA resulted in few differences in these parameters. However, during a second …

Sex Differences In Spatial Accuracy Relate To The Neural Activation Of Antagonistic Muscles In Young Adults, Agostina Casamento-Moran, Sandra K. Hunter, Yen-Ting Chen, Min-Hyuk Kwon, Emily J. Fox, Basma Yacoubi, Evangelos A. Christou

Exercise Science Faculty Research and Publications

Sex is an important physiological variable of behavior, but its effect on motor control remains poorly understood. Some evidence suggests that women exhibit greater variability during constant contractions and poorer accuracy during goal-directed tasks. However, it remains unclear whether motor output variability or altered muscle activation impairs accuracy in women. Here, we examine sex differences in endpoint accuracy during ankle goal-directed movements and the activity of the antagonistic muscles. Ten women (23.1 ± 5.1 years) and 10 men (23 ± 3.7 years) aimed to match a target (9° in 180 ms) with ankle dorsiflexion. Participants performed 50 trials and we …

Physical Activity Modulates Corticospinal Excitability Of The Lower Limb In Young And Old Adults, Hamidollah Hassanlouei, Christopher W. Sundberg, Ashleigh E. Smith, Andrew Kuplic, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Aging is associated with reduced neuromuscular function, which may be due in part to altered corticospinal excitability. Regular physical activity (PA) may ameliorate these age-related declines, but the influence of PA on corticospinal excitability is unknown. The purpose of this study was to determine the influence of age, sex, and PA on corticospinal excitability by comparing the stimulus-response curves of motor evoked potentials (MEP) in 28 young (22.4 ± 2.2 yr; 14 women and 14 men) and 50 old adults (70.2 ± 6.1 yr; 22 women and 28 men) who varied in activity levels. Transcranial magnetic stimulation was used to …

Cardio-Protection Afforded By Β-Blockade Is Maintained During Resistance Exercise, Alexander V. Ng, Jason M. Conviser, Shawn S. Rockey, D. Paul Thomas

Exercise Science Faculty Research and Publications

Objectives

Whether or not the cardio-protective effect of β-adrenergic blockade is retained during resistance exercise has not been systematically evaluated. Therefore the purpose of this study was to measure selected cardiorespiratory responses to isometric exercise involving hand-gripping, single-leg extension, or double-leg dead-lift, under placebo (control), β₁-selective (atenolol), and non-selective (propranolol) adrenergic blockade conditions.

Design

Eleven young male adults were evaluated in a randomized, double-blinded, repeated measures study design and performed all three exercise modalities at 30% of maximal voluntary contraction under placebo, atenolol and propranolol conditions.

Methods

Heart rate, systolic and diastolic blood pressure, rate-pressure product, oxygen uptake, …

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 …

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 …

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 …

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 …

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 …

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 …

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.

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 …