Physiology Commons^™

Role Of Fat Content On The Structure And Function Of Human Skeletal Muscle, Joseph A. Gordon Iii

Doctoral Dissertations

Muscle size does not fully explain variations in muscle strength. Fat content has been implicated in muscle weakness, though this relationship remains unclear. The relationship between fat and strength may vary between scales (e.g., cellular, organ, and organism). The goal of this dissertation was to clarify the role of fat in the structure and function of muscle using in vitro and in vivo techniques across multiple scales in adults 21-45 years old. Study 1 tested the agreement of intramyocellular lipid (IMCL) content between oil red o (ORO) and magnetic resonance spectroscopy (MRS) techniques. These measures of IMCL were also compared …

Link Between Muscle And Whole-Body Energetic Responses To Exercise, Christopher M.T. Hayden

Masters Theses

Substantial evidence exists regarding how skeletal muscles use energy and how this affects muscular performance. What remains unclear is how characteristics of muscle energetics affect whole-body energetics during daily living, and what effects this may have on mobility. The goal of this study was to determine the associations between muscle and whole-body energetics including the relationships between: 1) muscle PCr depletion (∆PCr) in response to light intensity isotonic contractions and the oxygen deficit at the onset of a 30-min treadmill walk (30MTW), and, 2) muscle oxidative capacity and excess post-exercise oxygen consumption (EPOC; 30MTW), respiratory exchange ratio (RER; 30MTW), and …

Mechanisms Of Statin Effects On Muscle And Neuronal Proteostasis, Daniel Yu

University Scholar Projects

Statins are widely prescribed and used chronically, but we know little about the effects on long-term protein homeostasis during stress and aging. Our aim was to quantify the effect of statins on stress-induced protein damage. We administered atorvastatin in a dose-response curve in Caenorhabditis elegans under naïve control conditions and in conditions of hypertonic and heat stress known to induce muscle damage measurable as countable puncta in a polyglutamine aggregation model of damage. We observed that there is significant polyglutamine aggregation variability among worms at baseline and thus further study requires within experiment baseline controls, per worm. Our results are …

Mechanisms That Limit Oxidative Phosphorylation During High-Intensity Muscle Contractions In Vivo, Miles F. Bartlett

Doctoral Dissertations

Skeletal muscle oxidative capacity plays a critical role in human health and disease. Although current models of oxidative phosphorylation sufficiently describe skeletal muscle energetics during moderate-intensity contractions, much is still unknown about the mechanisms that control and limit oxidative phosphorylation during high-intensity contractions. In particular, the oxygen cost of force generation is augmented during exercise at workloads above the lactate threshold. Presently, it is unclear whether this augmentation in muscle oxygen consumption is driven by increased rates of oxidative ATP synthesis (ATP_OX) or by decreases in the efficiency of ATP_OX due to mitochondrial uncoupling. To address this …

The Effects Of Two Different Resistance Training Protocols With Similar Volume On Muscular Strength, Muscle Thickness, And Fat-Free Mass, Cory Worthey

Theses and Dissertations

The manipulation of exercise volume, intensity, and order is associated with producing different musculoskeletal changes. These resistance training program variables affect mechanical tension and metabolic stress associated with resistance training, therefore affecting strength and hypertrophic outcomes. PURPOSE: The purpose of this study was to examine the effects of two different volume-equated total body exercise protocols over 9 weeks using compound exercises on muscular strength, muscle thickness, and fat-free mass. METHODS: Eight well-trained men were randomly assigned to a hypertrophy-style protocol (HG) performing 3 sets of 10 repetitions with 90 seconds rest between sets (n = 4) or a strength-style protocol …

Lifestyle Contributors To Cardiovascular Disease Risk, Adam J. Berrones

Theses and Dissertations--Kinesiology and Health Promotion

Aortic stiffness is an independent risk factor that has prognostic value regarding future cardiovascular disease (CVD) events such as myocardial infarction, strokes, and heart failure. Although death rates due to coronary heart disease have declined in recent years, the leading global killer remains CVD and prevalence is still high. Understanding lifestyle contributors associated with aortic stiffness would provide the public with insight into targeting key health-related behaviors.

The purpose of this observational study was to examine the association of physical activity, physical function, and dietary quality as independent factors contributing to aortic stiffness in apparently healthy middle aged men. Fifty-two …

A Comparison Of Three Computer-Based Methods Used To Determine Emg Signal Amplitude, Doug Renshaw*, Matthew R. Bice†, Camille Cassidy‡, James A. Eldridge‡, Douglas W. Powell‡

James Eldridge

Electromyography is a commonly used method to determine relative effort and neuromuscular drive to skeletal muscle. A limitation of the interpretation of EMG within the literature is the many methods used to determine the intensity of muscle activation. In the current study, ten healthy young adults performed a level walking task while EMG was recorded from the tibialis anterior, medial gastrocnemius and fibularis longus. The EMG data were rectified and smoothed using the root mean squared (RMS). Peak RMS (pRMS), mean RMS (mRMS) and integrated EMG (iEMG) were normalized to the peak value within the subject and were used to …

Twenty-One Days Of Lunar Environment Alters Muscle Fiber Areas In Mouse Gastrocnemius, Edwin M. Savio, Kevin L. Shimkus, Jeff M. Hord, John Will Deaver, Michael P. Wiggs, Brandon R. Macias, Florence Lima, Ramon D. Boudreaux, Yasaman Shirazi-Fard, Elizabeth S. Greene, Les A. Braby, Harry A. Hogan, John M. Lawler, Susan A. Bloomfield, James D. Fluckey

International Journal of Exercise Science: Conference Proceedings

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The Effect Of Music As A Motivational Tool On Isokinetic Concentric Performance In College Aged Students, Maurice M. Godwin, Ronnette T. Hopson, Carley K. Newman, Timothy J. Leszczak

International Journal of Exercise Science

International Journal of Exercise Science 7(1) : 54-61, 2014. Music has been identified as a motivational tool in physical activity and associated with improved performance in aerobic and anaerobic exercise. However, the effects of music on isokinetic strength testing have not been examined. The purpose of this study was to measure the difference in lower limb isokinetic force output in males and females when exposed to a motivational environment (arousing music) and non-motivational environment (silence). A 2 x 2 analysis of variance (group x gender) was used with participants (n = 19; 12 male, 7 female) serving as their …

Effects Of Multiple Bouts Of Long-Duration Hindlimb Unloading And Recovery On Rat Plantaris Muscle, Emily E. Jaroszewski, Kevin L. Shimkus, Yasaman Shirazi-Fard, Harry A. Hogan, James D. Fluckey

International Journal of Exercise Science: Conference Proceedings

Exposure to microgravity results in a rapid reduction of muscle mass. However, few studies exist designed to examine the effects of multiple long-term exposures to microgravity with alternating recovery periods on skeletal muscle. To determine what happens to the recovery of skeletal muscle when faced with subsequent unloading and recovery periods. Male Sprague-Dawley (6 mo) were assigned to the following groups as shown in figure 1 below: 28d hindlimb unloading (1HU), 28d HU session followed by a 56d recovery bout of normal cage ambulation at 1g (1HU+REC), 2 cycles of 28d HU with a 56d recovery period between unloadings (2HU), …

A Comparison Of Three Computer-Based Methods Used To Determine Emg Signal Amplitude, Doug Renshaw*, Matthew R. Bice†, Camille Cassidy‡, James A. Eldridge‡, Douglas W. Powell‡

International Journal of Exercise Science

Electromyography is a commonly used method to determine relative effort and neuromuscular drive to skeletal muscle. A limitation of the interpretation of EMG within the literature is the many methods used to determine the intensity of muscle activation. In the current study, ten healthy young adults performed a level walking task while EMG was recorded from the tibialis anterior, medial gastrocnemius and fibularis longus. The EMG data were rectified and smoothed using the root mean squared (RMS). Peak RMS (pRMS), mean RMS (mRMS) and integrated EMG (iEMG) were normalized to the peak value within the subject and were used to …

A Motor And A Brake: Two Leg Extensor Muscles Acting At The Same Joint Manage Energy Differently In A Running Insect, Anna N. Ahn, Robert J. Full

All HMC Faculty Publications and Research

The individual muscles of a multiple muscle group at a given joint are often assumed to function synergistically to share the load during locomotion. We examined two leg extensors of a running cockroach to test the hypothesis that leg muscles within an anatomical muscle group necessarily manage (i.e. produce, store, transmit or absorb) energy similarly during running. Using electromyographic and video motion-analysis techniques, we determined that muscles 177c and 179 are both active during the first half of the stance period during muscle shortening. Using the in vivo strain and stimulation patterns determined during running, we measured muscle power output. …