Sports Sciences Commons^™

A Biomechanical Comparison Of Successful And Unsuccessful Power Clean Attempts, Kristof Kipp, Carolyn M. Meinerz

Exercise Science Faculty Research and Publications

Although the power clean is an almost ubiquitous exercise in the strength and conditioning setting, relatively little is known about the biomechanics of successful and unsuccessful power clean lift attempts. The purpose of this study was to determine biomechanical differences between successful and unsuccessful power clean lift attempts in male collegiate athletes. Fifteen male lacrosse players (Age: 20.1 ± 1.2; Height: 1.78 ± 0.07 m; Body mass: 80.4 ± 8.1 kg; Relative one-repetition maximum power clean: 1.25 ± 0.13 kg/kg) were videotaped during a lifting session that required the completion of maximal effort power cleans to establish a one-repetition maximum. …

The Relevance Of Sex Differences In Performance Fatigability, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Performance fatigability differs between men and women for a range of fatiguing tasks. Women are usually less fatigable than men, and this is most widely described for isometric fatiguing contractions and some dynamic tasks. The sex difference in fatigability is specific to the task demands so that one mechanism is not universal, including any sex differences in skeletal muscle physiology, muscle perfusion, and voluntary activation. However, there are substantial knowledge gaps about the task dependency of the sex differences in fatigability, the involved mechanisms, and the relevance to clinical populations and with advanced age. The knowledge gaps are in part …

Mechanical Demands Of The Hang Power Clean And Jump Shrug: A Joint-Level Perspective, Kristof Kipp, Philip Malloy, Jordan Smith, Matthew D. Giordanelli, Michael T. Kiely, Christopher Geiser, Timothy J. Suchomel

Exercise Science Faculty Research and Publications

The purpose of this study was to investigate the joint- and load-dependent changes in the mechanical demands of the lower extremity joints during the hang power clean (HPC) and the jump shrug (JS). Fifteen male lacrosse players were recruited from an NCAA DI team, and completed three sets of the HPC and JS at 30%, 50%, and 70% of their HPC 1-Repetition Maximum (1-RM HPC) in a counterbalanced and randomized order. Motion analysis and force plate technology were used to calculate the positive work, propulsive phase duration, and peak concentric power at the hip, knee, and ankle joints. Separate three-way …

Muscle-Specific Effective Mechanical Advantage And Joint Impulse In Weightlifting, Kristof Kipp, Chad Harris

Exercise Science Faculty Research and Publications

Lifting greater loads during weightlifting exercises may theoretically be achieved through increasing the magnitudes of net joint impulses or manipulating the joints’ effective mechanical advantage (EMA). The purpose of this study was to investigate muscle-specific EMA and joint impulse as well as impulse-momentum characteristics of the lifter-barbell system across a range of external loads during the execution of the clean. Collegiate-level weightlifters performed submaximal cleans at 65, 75, and 85% of their 1-repetition maximum (1-RM) while data from a motion analysis system and a force plate were used to calculate lifter-barbell system impulse and velocity, as well as net extensor …

Reliability And Validity Of Ratings Of Perceived Exertion In Persons With Multiple Sclerosis, Brice T. Cleland, Benjamin A. Ingraham, Molly C. Pitluck, Alexander V. Ng

Exercise Science Faculty Research and Publications

Objective: To test the reliability and validity of using the Borg rating of perceived exertion (RPE) scale (ratings 6e20) in persons with multiple sclerosis (PwMS).

Design: Nonrandomized repeated measures.

Setting: Research laboratory.

Participants: Volunteer sample (N=27) comprised of 16 PwMS (10 women) and 11 age-matched persons without multiple sclerosis (MS) (6 women). Clinical measures included symptomatic fatigue, depression, and MS functional capacity.

Interventions: A submaximal cycling test was performed to estimate maximal capacity. Participants then pedaled for 2 minutes at 50% and 60% of predicted maximal oxygen consumption per unit time (V̇O₂), and physiological measures and RPE were …

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 …

The Two-Hour Marathon: What's The Equivalent For Women?, Sandra K. Hunter, Michael J. Joyner, Andrew M. Jones

Exercise Science Faculty Research and Publications

The principal characteristic of the runner who may break the two-hour barrier in the marathon will be their sex: the person will be male. The fastest men outperform the fastest women because of sex differences in physiology including a higher VȮ2 max. This viewpoint addresses the questions of what is the two-hour equivalent for women, and who will break this barrier? The current sex difference in the world record for the marathon is ~10% which is slightly less than the mean sex difference in performance usually documented between elite men and women distance runners. Based on comparisons of the top …

Men Are More Likely Than Women To Slow In The Marathon, Robert O. Deaner, Rickey E. Carter, Michael J. Joyner, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Studies on nonelite distance runners suggest that men are more likely than women to slow their pace in a marathon.

Purpose: This study determined the reliability of the sex difference in pacing across many marathons and after adjusting women's performances by 12% to address men's greater maximal oxygen uptake and also incorporating information on racing experience.

Methods: Data were acquired from 14 US marathons in 2011 and encompassed 91,929 performances. For 2929 runners, we obtained experience data from a race-aggregating Web site. We operationalized pace maintenance as the percentage change in pace observed in the second half of the marathon …

Effects Of Sex And Gender On Adaptation To Space: Musculoskeletal Health, Lori Ploutz-Snyder, Susan Bloomfield, Scott M. Smith, Sandra K. Hunter, Kim Templeton, Debra Bemben

Exercise Science Faculty Research and Publications

There is considerable variability among individuals in musculoskeletal response to long-duration spaceflight. The specific origin of the individual variability is unknown but is almost certainly influenced by the details of other mission conditions such as individual differences in exercise countermeasures, particularly intensity of exercise, dietary intake, medication use, stress, sleep, psychological profiles, and actual mission task demands. In addition to variations in mission conditions, genetic differences may account for some aspect of individual variability. Generally, this individual variability exceeds the variability between sexes that adds to the complexity of understanding sex differences alone. Research specifically related to sex differences of …

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 …

Differences In Kinematic Control Of Ankle Joint Motions In People With Chronic Ankle Instability, Kristof Kipp, Rianna M. Palmieri-Smith

Exercise Science Faculty Research and Publications

Background

People with chronic ankle instability display different ankle joint motions compared to healthy people. The purpose of this study was to investigate the strategies used to control ankle joint motions between a group of people with chronic ankle instability and a group of healthy, matched controls.

Methods

Kinematic data were collected from 11 people with chronic ankle instability and 11 matched control subjects as they performed a single-leg land-and-cut maneuver. Three-dimensional ankle joint angles were calculated from 100 ms before, to 200 ms after landing. Kinematic control of the three rotational ankle joint degrees of freedom was investigated by …

Correlations Between Internal And External Power Outputs During Weightlifting Exercise, Kristof Kipp, Chad Harris, Michelle B. Sabick

Exercise Science Faculty Research and Publications

Identifying loads that maximize mechanical power is important because training at such loads may optimize gains in dynamic athletic performance. The purpose of this study was to examine correlations between measures of external mechanical power output and internal mechanical joint power output across different loads during a weightlifting exercise. Ten subjects performed 3 sets of the clean exercise at 65, 75, and 85% of 1 repetition maximum (1RM). Peak external mechanical power output was calculated with 4 commonly used methods, whereas an inverse dynamics approach was used to calculate peak internal mechanical power output for the hip, knee, and ankle …

Fatigability And Recovery Of Arm Muscles With Advanced Age For Dynamic And Isometric Contractions, Tejin Yoon, Bonnie Schlinder-Delap, Sandra K. Hunter

Exercise Science Faculty Research and Publications

This study determined whether age-related mechanisms can increase fatigue of arm muscles during maximal velocity dynamic contractions, as it occurs in the lower limb. We compared elbow flexor fatigue of young (n = 10, 20.8 ± 2.7 years) and old men (n = 16, 73.8 ± 6.1 years) during and in recovery from a dynamic and an isometric postural fatiguing task. Each task was maintained until failure while supporting a load equivalent to 20% of maximal voluntary isometric contraction (MVIC) torque. Transcranial magnetic stimulation (TMS) was used to assess supraspinal fatigue (superimposed twitch, SIT) and muscle relaxation. Time …

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 …

Sex Differences In Marathon Running With Advanced Age: Physiology Or Participation?, Sandra K. Hunter, Alyssa A. Stevens

Exercise Science Faculty Research and Publications

The sex difference in marathon performance increases with age and place of the finisher, even at the elite level. Sociological factors may explain the increased sex gap, but there is limited empirical evidence for specific factors.

Purpose: The purposes of this study were to determine the sex difference in velocity for the marathon across the place of finisher (1st–10th place) with advanced age and (2) to determine the association between the sex difference in participation (ratio of men-to-women finishers) and the sex difference in running velocity.

Methods: Running times of the first 10 placed men and women in the 5-yr …

Electromyographical Analysis Of Lower Extremity Muscle Activation During Variations Of The Loaded Step-Up Exercise, Christopher J. Simenz, Luke Garceau, Brittney Lutsch, Timothy J. Suchomel, William P. Ebben

Exercise Science Faculty Research and Publications

The loaded step-up exercise allows strength and conditioning practitioners to incorporate a unilateral resistance for athletes while performing extension at the hip, knee, and plantar flexion at the ankle. This study evaluated the activation of the biceps femoris (BF), gluteus maximus (GMx), gluteus medius (GMe), rectus femoris, semitendinosus (ST), vastus lateralis, and vastus medialis during 4 variations of the step-up exercise to assess the specific muscle training stimulus of each exercise variation. The exercises included the step-up, crossover step-up, diagonal step-up, and lateral step-up. Fifteen women who regularly engaged in lower body resistance training performed the 4 exercises with 6 …

Weightlifting Performance Is Related To Kinematic And Kinetic Patterns Of The Hip And Knee Joints, Kristof Kipp, Josh Redden, Michelle B. Sabick, Chad Harris

Exercise Science Faculty Research and Publications

The purpose of this study was to investigate the correlations between biomechanical outcome measures and weightlifting performance. Joint kinematics and kinetics of the hip, knee, and ankle were calculated while 10 subjects performed a clean at 85% of 1 repetition maximum (1RM). Kinematic and kinetic time-series patterns were extracted with principal components analysis. Discrete scores for each time-series pattern were calculated and used to determine how each pattern was related to body mass–normalized 1RM. Two hip kinematic and 2 knee kinetic patterns were significantly correlated with relative 1RM. The kinematic patterns captured hip and trunk motions during the first pull …

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 …

Folic Acid Supplementation Improves Vascular Function In Professional Dancers With Endothelial Dysfunction, Anne Z. Hoch, Paula E. Papanek, Aniko Szabo, Michael E. Widlansky, David D. Gutterman

Exercise Science Faculty Research and Publications

Objective

To determine if folic acid supplementation improves vascular function (brachial artery flow-mediated dilation [FMD]) in professional dancers with known endothelial dysfunction.

Design

Prospective cross-sectional study.

Setting

Academic institution in the Midwestern United States.

Subjects

Twenty-two professional ballet dancers volunteered for this study.

Main Outcome Measures

Subjects completed a 3-day food record to determine caloric and micronutrient intake. Menstrual status was determined by interview and questionnaire. Endothelial function was determined as flow-induced vasodilation measured by high-frequency ultrasound of the brachial artery. A change in brachial diameter of

Results

Sixty-four percent of dancers (n = 14) had abnormal brachial artery FMD …

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.

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 …