Rehabilitation and Therapy Commons^™

Muscle-Specific Contributions To Lower Extremity Net Joint Moments While Squatting With Different External Loads, Kristof Kipp, Hoon Kim, William I. Wolf

Exercise Science Faculty Research and Publications

The purpose of this study was to determine muscle-specific contributions to lower extremity net joint moments (NJMs) during squats with different external loads. Nine healthy subjects performed sets of the back squat exercise with 0, 25, 50, and 75% of body mass as an added external load. Motion capture and force plate data were used to calculate NJMs and to estimate individual muscle forces via static optimization. Individual muscle forces were multiplied by their respective moment arms to calculate the resulting muscle-specific joint moment. Statistical parametric mapping (α = 0.05) was used to determine load-dependent changes in the time series …

Maximal Strength In Relation To Force And Velocity Patterns During Countermovement Jumps, Michael H. Haischer, John Krzyszkowski, Stuart Roche, Kristof Kipp

Exercise Science Faculty Research and Publications

Maximal strength is important for the performance of dynamic athletic activities, such as countermovement jumps (CMJ). Although measures of maximal strength appear related to discrete CMJ variables, such as peak ground reaction forces (GRF) and center-of-mass (COM) velocity, knowledge about the association between strength and the time series patterns during CMJ will help characterize changes that can be expected in dynamic movement with changes in maximal strength. Purpose: To investigate the associations between maximal strength and GRF and COM velocity patterns during CMJ. Methods: Nineteen female college lacrosse players performed 3 maximal-effort CMJs and isometric midthigh pull. GRF …

Hip And Knee Joint Angle Patterns And Kicking Velocity In Female And Male Professional Soccer Players: A Principal Component Analysis Of Waveforms Approach, Archit Navandar, Kristof Kipp, Enrique Navarro

Exercise Science Faculty Research and Publications

This study used principal component analysis (PCA) of waveforms to extract movement patterns from hip and knee angle time-series data; and determined if the extracted movement patterns were predictors of ball velocity during a soccer kick. Twenty-three female and nineteen male professional soccer players performed maximal effort instep kicks while motion capture and post-impact ball velocities data were recorded. Three-dimensional hip and knee joint angle time-series data were calculated from the beginning of the kicking leg’s backswing phase until the end of the follow-through phase and entered into separate PCAs for females and males. Three principal components (PC) (i.e., movement …

Influence Of The Bar Position On Joint-Level Biomechanics During Isometric Pulling Exercises, Nayun Ahn, Hoon Kim, John Krzyszkowski, Stuart Roche, Kristof Kipp

Exercise Science Faculty Research and Publications

The purpose of this study was to investigate the influence of the bar position on ankle, knee, and hip net joint moments (NJMs), relative muscular effort (RME), and vertical ground reaction forces (GRFs) during isometric pulling exercises, such as the isometric midthigh pull. Eight female lacrosse athletes performed maximal effort isometric pulls at 3 different bar positions (low: above patella, mid: midthigh, and high: crease of hip) while motion capture and GRF data were recorded. Net joint moments were calculated with inverse dynamics. Relative muscle effort was defined as the ratio between the inverse dynamics NJMs and the maximum theoretical …

Wellness And Multiple Sclerosis: The National Ms Society Establishes A Wellness Research Working Group And Research Priorities, Robert W. Motl, Ellen M. Mowry, Dawn M. Ehde, Nicholas G. Larocca, Kathy E. Smith, Kathleen Costello, Lynne Shinto, Alex V. Ng, Amy B. Sullivan, Barbara Geisser, Kevin K. Mccully, Bo Fernhall, Malachy Bishop, Matthew Plow, Patrizia Casaccia, Nancy D. Chiaravalloti

Exercise Science Faculty Research and Publications

Background:

People with multiple sclerosis (MS) have identified “wellness” and associated behaviors as a high priority based on “social media listening” undertaken by the National MS Society (i.e. the Society).

Objective:

The Society recently convened a group that consisted of researchers with experience in MS and wellness-related research, Society staff members, and an individual with MS for developing recommendations regarding a wellness research agenda.

Method:

The members of the group engaged in focal reviews and discussions involving the state of science within three approaches for promoting wellness in MS, namely diet, exercise, and emotional wellness.

Results:

That process informed a …

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 …

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 …

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 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) …

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 …

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, …

Pain Relief In Older Adults Following Static Contractions Is Not Task-Dependent, Kathy J. Lemley, Breanna Drewek, Lauren Miller, Sandra K. Hunter, Marie K. Hoeger Bement

Physical Therapy Faculty Research and Publications

Pain complaints increase with age. Exercise is frequently utilized for pain relief but the optimal exercise prescription to relieve pain is not clear. Following static contractions, young adults experience the greatest pain relief with low intensity, long duration contractions. The pain response to static contractions in older adults however is unknown.

PURPOSE : To compare pain reports in healthy older adults before and after static contractions of varying intensity and duration.

METHODS: Pain perception was assessed in 23 healthy older adults (11 men, 12 women; 72.0 ± 6.3 yrs) using a pressure pain device consisting of a 10 N force …

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 …

Does Plasma Ss-Endorphin Influence Exercise-Induced Hypoalgesia In Healthy Adults?, Kathy Lemley

Maria Dittman Library Research Competition: Student Award Winners

Anecdotal reports can be found in the literature of athletes who suffer from an injury, yet continue to participate in their sport with little or no pain. These reports have resulted in an interest in the possible role of stress, including exercise, in analgesia. Exercise-induced hypoalgesia (EIH), a decrease in pain perception following exercise, has been found to occur in healthy adults. In the 1970’s opioid peptides with analgesic properties were discovered (Dalayeun, Nores & Bergal, 1993). One of these peptides, β-endorphin, is believed to be released from the anterior pituitary into the circulation under a variety of stressors, including …