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Full-Text Articles in Life Sciences

Constraining Kinematics During Single-Leg Squats And Step-Ups Can Reduce Quadratus Lumborum Activation And Facilitate Gluteal Activation, Shaylyn Kowalchuk Aug 2016

Constraining Kinematics During Single-Leg Squats And Step-Ups Can Reduce Quadratus Lumborum Activation And Facilitate Gluteal Activation, Shaylyn Kowalchuk

Electronic Thesis and Dissertation Repository

Increased quadratus lumborum activation and decreased gluteal activation may lead to lateral pelvic drop and increased hip adduction and internal rotation during single-leg exercises. These activation patterns and motions are associated with low back pain or lower extremity injuries. The purpose of this study was to evaluate if mechanically restricting hip adduction and internal rotation of the femur affected muscle activation. Twenty female track and field athletes performed single-leg squats and step-ups, and the quadratus lumborum, gluteus medius and maximus muscles activations were measured with surface electromyography. This study tested the hypothesis that mechanically restricted exercises would decrease quadratus lumborum ...


Exercise-Induced Glycogen Reduction Increases Muscle Activity, Matthew S. Tenan, J. Troy Blackburn, Robert G. Mcmurray Jul 2016

Exercise-Induced Glycogen Reduction Increases Muscle Activity, Matthew S. Tenan, J. Troy Blackburn, Robert G. Mcmurray

International Journal of Exercise Science

International Journal of Exercise Science 9(3): 336-346, 2016. Intramuscular glycogen stores are an important energy source during extended bouts of strenuous exercise. A substantial reduction in glycogen could influence neural muscular drive and result in a decreasing quality of exercise performance and potentially increased injury rates. The aim of this study was to examine the effect of glycogen reduction on motor drive as determined by the surface electromyogram (EMG) amplitude and median frequency during a cycling graded exercise test. Eight trained cyclists performed a discontinuous cycling graded exercise test to exhaustion under both normal and glycogen reduced conditions. EMG ...


Time Course Of Changes In Neuromuscular Parameters During Fatiguing High-Load And Low-Load Concentric Dynamic Constant External Resistance Leg Extension Muscle Actions, Cory M. Smith Apr 2016

Time Course Of Changes In Neuromuscular Parameters During Fatiguing High-Load And Low-Load Concentric Dynamic Constant External Resistance Leg Extension Muscle Actions, Cory M. Smith

Nutrition & Health Sciences Dissertations & Theses

The purpose of this study was to simultaneously assess electromyographic (EMG) and mechanomyographic (MMG) signals to examine the time course of changes in EMG amplitude, EMG frequency, MMG amplitude, and MMG frequency from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) muscles during high-load (70%1 repetitions maximum; 1-RM) and low-load (30% 1-RM) concentric, dynamic constant external resistance (DCER) leg extension muscle actions to failure. Twelve men performed two randomized visits consisting of either 30 or 70% 1-RM DCER leg extension muscle actions to failure. Maximal voluntary isometric contractions (MVIC) and 1-RM measurements were performed before and ...


Electromyography Study Of Muscle Fatigue During Isometric Exercises In Swimmers And Non-Swimmers, Tiffany Aeling Jan 2016

Electromyography Study Of Muscle Fatigue During Isometric Exercises In Swimmers And Non-Swimmers, Tiffany Aeling

Theses, Dissertations and Capstones

The use of electromyography (EMG) techniques offer strong evaluation of musculature fatigue during activity in different exercises. Studies show that EMG can be used to monitor fatigue patterns in muscles composing the upper extremities and thoracic areas of the human body by analyzing median frequency values. Advances in muscle fatigue research have been critical for improving rehabilitation programs for patients with musculoskeletal conditions. Despite these developments, many collegiate athletes are still at high risk for muscle injury on and off the playing field. Therefore, in order to help reduce injury numbers, it is important that current research focus on the ...


An Evaluation Of Modern Day Kitchen Knives: An Ergonomic And Biomechanical Approach, Olivia Morgan Janusz Jan 2016

An Evaluation Of Modern Day Kitchen Knives: An Ergonomic And Biomechanical Approach, Olivia Morgan Janusz

Graduate Theses and Dissertations

The focus of this study was to evaluate how different knife characteristics affect the consumer's ability to slice vegetables. There are many variables to a knife and there are beliefs about what makes for a better knife. There are two common multipurpose knives used for slicing vegetables, the chef knife and the santoku knife. The aim of the first portion of the study was to investigate if there is a difference in cutting between a chef knife and a santoku knife, a ceramic knife and a stainless steel knife, and a sharp and dull knife in terms of muscle ...


The Effect Of Cardiorespiratory Fitness On The Assessment Of The Physical Working Capacity At The Fatigue Threshold, Brittney M. Mikkelsen, Jorge Zuniga, William K. Herron, Frances E. Frauso, Anne N. Pulliam Jan 2016

The Effect Of Cardiorespiratory Fitness On The Assessment Of The Physical Working Capacity At The Fatigue Threshold, Brittney M. Mikkelsen, Jorge Zuniga, William K. Herron, Frances E. Frauso, Anne N. Pulliam

Journal Articles

Purpose: The purpose of this study was to determine if different cardiorespiratory fitness levels (maximal oxygen uptake or VO2max) affect neuromuscular fatigue as measured by the physical working capacity at the fatigue threshold (PWCFT). Methods: Fourteen adults (14 men; mean ± SD; age = 20.79 ± 0.89 years; body weight = 80.7 ± 10.91 kg; height = 178.4 ± 5.29 cm) volunteered to participate in the investigation. Each participant performed an incremental cycle ergometry test to fatigue while electromyographic (EMG) signals were measured from the vastus lateralis (VL) muscle. Mean, standard deviation, and range values were calculated for the power outputs ...


Neural Recovery Rates Of Knee Extensors Following A Resistance Exercise Protocol, Darren Michael Polk Jan 2016

Neural Recovery Rates Of Knee Extensors Following A Resistance Exercise Protocol, Darren Michael Polk

LSU Master's Theses

Fatigue can manifest in the human body in a multitude of ways, one of these is neural-based fatigue. Neural-based fatigue occurs when the nerve fails to activate a muscle (Brooks et al., 2005). The purpose of this research is to investigate rates of neural recovery following a resistance exercise protocol. A pre-test consisting of a 5-second maximum voluntary isometric knee extension was performed. Next, each subject performed a resistance exercise protocol consisting of 5 sets of 10 repetitions of isokinetic knee extensions. Post-tests following the resistance exercise protocol consisted of 5-second maximum voluntary isometric knee extensions after 1, 5, 10 ...


A Complete Kinematic, Kinetic, And Electromyographical Analysis Of The Football Throw In Collegiate Quarterbacks, Kyle R. Bohnert Jan 2016

A Complete Kinematic, Kinetic, And Electromyographical Analysis Of The Football Throw In Collegiate Quarterbacks, Kyle R. Bohnert

Theses and Dissertations--Kinesiology and Health Promotion

The biomechanics of the overhead throw has been extensively studied in regards to baseball pitching. However, an understanding of the proper mechanics needed to successfully throw a football has not previously been investigated. Thus, the purpose of this study was to investigate the kinematics, kinetics, and electromyography of the football throws in elite quarterbacks. Three collegiate quarterbacks were evaluated using a multi-camera motion capture system and electromyography electrodes. The results of this study are able to give a breakdown in the types of mechanics needed in each of the phases of the throw. This study demonstrated that during the early ...


Central And Peripheral Weight Gain Affect Trunk Kinematics And Lower-Extremity Muscle Activation Differently During Sit-To-Stand, Michelle Christine Walaszek Jan 2016

Central And Peripheral Weight Gain Affect Trunk Kinematics And Lower-Extremity Muscle Activation Differently During Sit-To-Stand, Michelle Christine Walaszek

Theses and Dissertations--Kinesiology and Health Promotion

Background: Obesity-induced alterations in biomechanics and muscle recruitment during activities of daily living, such as sit-to-stand (STS) are often attributed to increases in adipose tissue (AT) mass. Central or peripheral distribution of AT may differently affect biomechanics and muscle recruitment.

Methods: Fifteen healthy, normal weight (BMI 22.4 ± 1.9 kg/m2, 24.1 ± 4.2 years) subjects volunteered. External loads equivalent to a 5 kg/m2 BMI increase were applied in three conditions: unloaded (UN), centrally loaded (CL), and peripherally loaded (PL). Subjects completed three successful STS movements in a backless chair under each load condition in ...


Static Stretching And Preconditioning Exercise Augments Power Output In Recreational Athletes, Mark R. Mason Jan 2016

Static Stretching And Preconditioning Exercise Augments Power Output In Recreational Athletes, Mark R. Mason

Theses and Dissertations--Kinesiology and Health Promotion

The purpose of this study was to determine the independent and combined effects of performing a preconditioning exercise and antagonist stretching on vertical jump (VJ) performance. Twenty club rugby players performed a VJ in four conditions: control condition, following static stretching, following a preconditioning exercise, and following the combined treatment of static stretching and a preconditioning exercise. Electromyographic (EMG) activity was measured in the gluteus maximus, vastus lateralis, gastrocnemius medialis, and tibialis anterior during the VJ trials. Repeated measures ANOVA were used to compare VJ and EMG outcomes across conditions. A Bonferroni correction was used to account for multiple post-hoc ...


Relationship Between Metabolic By-Products And Nervous System Failure/Fatigue, Tyler Mitchell Farney Jan 2016

Relationship Between Metabolic By-Products And Nervous System Failure/Fatigue, Tyler Mitchell Farney

LSU Doctoral Dissertations

Fatigue has generally been defined as an acute impairment of exercise/sport performance that includes both an increase in the perceived effort necessary to exert a desired force or power output, and the inability to produce the desired force or power output. The majority of research to date looking at fatigue has focused upon substrate utilization, however, what is relatively unknown is the contribution the nervous system has upon fatigue. Therefore, the purpose of this dissertation was to investigate potential mechanisms that relate to neural fatigue. An additional purpose was to determine if there were any relationships between metabolic by-products ...