Ethan C Hill

Ethan C Hill
University of Central Florida | UCF · School of Kinesiology and Physical Therapy

PhD

About

108
Publications
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Introduction
The primary focus of our research is to identify the exercise modality that is most effective and efficient at stimulating muscle hypertrophy and increasing muscle strength in men and women. We examine eccentric contraction-based resistance training, low-load resistance training, blood flow restriction, and local vs. systemic hypoxia. Our lab is currently applying our findings to help mitigate age-related losses in muscle function and to identify exercise countermeasures during spaceflight.

Publications

Publications (108)
Article
Full-text available
Purpose: The purpose of this study was to examine the acute effects of low-load blood flow restriction (LLBFR) and low-load non-BFR (LL) on neuromuscular function following a bout of standardized, fatiguing leg extension muscle actions. Methods: Fourteen men (mean age ± SD = 23±4 yrs) volunteered to participate in this investigation and randomly...
Article
Full-text available
Proppe, CE, Rivera, PM, Beltran E, Hill EC. Effects of a Cooling Vest on a 10-km Cycling Performance and Neuromuscular Function in a Thermoneutral Environment. JEPonline 2022;25(3):92-105. Previous research has shown that cooling interventions can alter exercise performance, comfort, and rating of perceived exertion (RPE) in hot environments but le...
Article
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Women exhibit an attenuated exercise pressor reflex (EPR) when compared to men. The influence of sex-specific mechanisms related to the EPR and performance fatigability remain to be fully elucidated. The purpose was to determine the impact of oxygenation and metabolic efficiency on sex-specific performance fatigability and increases in mean arteria...
Article
Rivera, Paola M., Chris E. Proppe, Esther Beltran, and Ethan C. Hill. Acute effects of local ischemic hypoxia and systemic hypoxemia on neuromuscular and cognitive function. High Alt Med Biol. 00:000-000, 2021. Background: The application of blood flow restriction (BFR) induces local ischemic hypoxia within the muscle(s) distal to the restriction d...
Article
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PurposeLiterature is conflicted on whether electromechanical delay durations decrease following resistance training programs. Therefore, the aim of this study is to examine the contributions and durations of the electrochemical (EMDE-M) and mechanical (EMDM-F) components to the overall electromechanical delay (EMDE-F) during step isometric muscle a...
Article
BACKGROUND: Low-load resistance training with blood flow restriction (LL + BFR) attenuated delayed onset muscle soreness (DOMS) under some conditions. OBJECTIVE: The purpose of this study examined the effects of reciprocal concentric-only elbow flexion-extension muscle actions at 30% of peak torque on indices of DOMS. METHODS: Thirty untrained wome...
Article
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Purpose The present study examined acute normobaric hypoxic exposure on the number of repetitions to failure, electromyographic (EMG) repetition duration (Time), EMG root mean square (RMS) and EMG mean power frequency (MPF) during biceps brachii (BB) dynamic constant external resistance (DCER) exercise. Methods Thirteen subjects performed two sets...
Article
The purpose of the present study was to examine the acute changes in muscle swelling (as assessed by muscle thickness and echo intensity) and muscle blood flow associated with an acute bout of low-load blood flow restriction (LLBFR) and low-load non-blood flow restriction (LL) exercise. Twenty women (mean±SD;22±2yrs) volunteered to perform an acute...
Article
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Purpose The purpose of this investigation was to examine the individual and composite patterns of responses and time-course of changes in muscle size, strength, and edema throughout a 4 week low-load blood flow restriction (LLBFR) resistance training intervention. Methods Twenty recreationally active women (mean ± SD; 23 ± 3 years) participated in...
Article
BACKGROUND: Few studies have examined sex differences in performance fatigability and the bilateral deficit in a dynamic modality. OBJECTIVES: The purpose of this study was to examine: 1) Leg-, mode-, and sex-specific differences in performance fatigability during maximal, dynamic leg extension muscle actions and; 2) the time course of fatigue-indu...
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Objectives: This study examined performance fatigability and the patterns of neuromuscular responses for electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) during bilateral (BL) and unilateral (UL) maximal, isokinetic leg extensions. Methods: Peak torque for each repetition and EMG and MMG signals...
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PurposeThe purpose of the present study was to examine the day-to-day consistency and inter-subject variability of composite and individual, neuromuscular and torque patterns of responses as a result of a fatiguing bout of maximal, bilateral, isokinetic leg extension muscle actions.Methods Ten men (Mean ± SD = 21.6 ± 2.5 years) completed two testin...
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BACKGROUND: Blood flow restriction (BFR) resistance training (RT) has garnered recent interest, but female-specific data remains scarce. OBJECTIVE: The purpose was to examine the effects of 2-wks of low-load concentric, isokinetic, reciprocal forearm flexion and extension training, with and without BFR on perceptual responses, performance fatigabil...
Thesis
BACKGROUND: The capacity to do work is greatly affected by high altitude exposure. Larger muscle groups of the lower body and exercises primarily aerobic in nature have been well investigated at high altitude. The present study examined acute altitude exposure on the number of repetitions to failure and electromyographic (EMG) repetition duration (...
Article
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Neltner TJ, Housh TJ, Smith CM, Anders JP, Keller JL, Hill EC, Schmidt RJ, Johnson GO. Similar Fatigue-Induced Changes in Neuromuscular Patterns of Responses for Contralateral Legs during Maximal Bilateral Leg Extensions. JEPonline 2020;23(2):1-17. The purpose of the present study was to compare individual and composite neuromuscular patterns of re...
Article
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The purpose of this investigation was to use the RPE clamp protocol to examine sex-related differences in performance fatigability and neuromuscular responses as the result of a sustained isometric leg extension muscle action anchored to RPE = 2. Twenty adults (10 men, 10 women) performed sustained muscle actions at RPE = 2 for 5-min. Maximal volun...
Article
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Purpose Low-load venous blood flow restriction resistance training (RT + BFR) has been demonstrated to increase muscle strength to a greater degree than low-load non-BFR resistance training (RT) during isotonic training, but no previous investigations have examined RT + BFR versus RT during isokinetic training. The purpose of the present study was...
Article
Objectives: Little is known regarding the variables or mechanisms mediating cross-education as a result of resistance training. Therefore, the purpose of the present study was to examine the effects of low-load eccentric-only blood flow restriction (Ecc-BFR) and low-load concentric-only BFR (Con-BFR) on indices of cross-education. Design: Thirty...
Article
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Previous studies have demonstrated that ayurvedic ingredients exhibit ergogenic (performance enhancing) properties, however, no previous studies have examined the ergogenic potential of Asparagus racemosus. The purpose of the present study was to examine the ergogenic efficacy of supplementation with 500 mg·d−1 of A. racemosus during bench press tr...
Article
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The purpose of the study was to examine the fatigue-related patterns of responses for electromyography (EMG), mechanomyography (MMG), and force during a sustained isometric muscle action anchored to RPE = 5. Ten men (22.9 ± 2.0 year) performed maximal voluntary isometric contractions (MVIC) prior to and following an isometric leg extension muscle a...
Article
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Keller, JL, Housh, TJ, Hill, EC, Smith, CM, Schmidt, RJ, and Johnson, GO. Are there sex-specific neuromuscular or force responses to fatiguing isometric muscle actions anchored to a high perceptual intensity? J Strength Cond Res XX(X): 000-000, 2019-The purpose of this study was to use the ratings of perceived exertion (RPE) clamp model to examine...
Article
The purpose of this study was to compare isokinetic peak torque and the patterns of responses for electromyographic (EMG) and mechanomyographic (MMG), amplitude (AMP) and mean power frequency (MPF) for bilateral (BL) versus unilateral (UL), maximal, isokinetic leg extensions. Eleven recreationally trained women (Mean ± SD: age 22.9 ± 0.9 yrs; body...
Article
Full-text available
Purpose Unaccustomed exercise can result in delayed onset muscle soreness (DOMS), particularly as a result of the eccentric phase of the muscle contraction. Resistance training combined with venous blood flow restriction (vBFR) may attenuate DOMS, but the available information in this regard is conflicting. Therefore, the purpose of this study was...
Article
Purpose: The purpose of this study was to examine the changes in reflex-electromechanical delay (EMD) as a result of 2- and 4-wks of variable resistance training (VRT) or dynamic constant external resistance (DCER) leg press training. Material and Methods: Thirty-six men were randomised into either the Control, DCER, or VRT groups. The DCER and VRT...
Article
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Purpose The mediators of the perception of effort during exercise are still unclear. The aim of the present study was to examine physiological responses during runs using a rating of perceived exertion (RPE)-clamp model at the RPE corresponding to the gas exchange threshold (RPEGET) and 15% above GET (RPEGET+15%) to identify potential mediators and...
Article
Jenkins, NDM, Miramonti, AA, Hill, EC, Smith, CM, Cochrane-Snyman, KC, Housh, TJ, and Cramer, JT. Mechanomyographic amplitude is sensitive to load-dependent neuromuscular adaptations in response to resistance training. J Strength Cond Res XX(X): 000-000, 2019-We examined the sensitivity of the mechanomyographic amplitude (MMGRMS) and frequency (MMG...
Article
Full-text available
The purpose of this study was to compare the composite, inter-individual, and intra-individual differences in the patterns of responses for electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) during fatiguing, maximal, bilateral, and isokinetic leg extension muscle actions. Thirteen recreationally acti...
Article
Objectives: This project proposes a unique methodology utilizing electromyography and mechanomyography to determine the intensity of a desired movement which may be useful in further developing decomposition algorithms for prosthetic controls. Methods: Ten males performed isometric leg extension muscle actions corresponding to 20, 40, 60, 80, an...
Article
The purposes of this study were to examine the effects of 4-wks of forearm flexion and extension blood flow restriction (BFR) resistance training versus non-BFR resistance training versus BFR without resistance training on: 1) muscle strength; 2) muscle power; 3) muscle size; and 4) neuromuscular adaptation. Forty women (mean±SD; 22±3 years) volunt...
Article
Objective: The purpose of this investigation was to examine the ability of the electromyographic (EMG) and mechanomyographic (MMG) amplitude versus torque relationships to track group and individual changes in muscle hypertrophy as a result of resistance training. Approach: Twelve women performed four weeks of forearm flexion blood flow restrict...
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Background: Shilajit is a safe, fluvic mineral complex exudate that is common to Ayurvedic medicine and is composed of fulvic acids, dibenzo-α-pyrones, proteins, and minerals. The purpose of this study was to examine the effects of 8 weeks of Shilajit supplementation at 250 mg·d− 1 (low dose) and 500 mg·d− 1 (high dose) versus placebo on maximal vo...
Article
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Purpose The purpose of the present study was to examine the fatigue-related patterns of responses for electromyography (EMG), mechanomyography (MMG), and force during a sustained, submaximal isometric leg extension muscle action anchored at RPE = 5. Methods Ten women (23.1 ± 2.3 year) performed two, maximal voluntary isometric contractions (MVIC)...
Article
Full-text available
Objectives The purpose of this study was to examine the effects of exercise intensity and strength on sex-related differences in eccentric peak torque (PT), muscle blood flow, and neuromuscular responses following fatiguing, submaximal forearm flexion eccentric protocols. Methods Thirty-six subjects were stratified by sex and strength into 4 equal...
Article
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Background Ultrasound has been used for noninvasive assessments of endothelial function in both clinical and athletic settings and to identify changes in muscle blood flow in response to exercise, nutritional supplementation, and occlusion. The purposes of the present study were to examine the reliability and relative contributions of arterial cros...
Article
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This study aimed to combine co-activation as well as anterior and posterior cruciate ligament force estimations with the motor unit activation strategies employed by the primary muscles that are involved in the movement at the knee joint. Fourteen male subject performed 25 maximal concentric isokinetic leg extension muscle actions at 120 s−1. Elect...
Article
The primary purpose of the present investigation was to examine sex-related differences as a result of fatiguing eccentric muscle actions on torque, muscle blood flow, electromyography, and mechanomyography. Eighteen men and 18 women performed peak torque trials prior to (pretest), immediately after (posttest), and 5-min after (recovery) completing...
Article
Full-text available
PurposeLow-intensity venous blood flow restriction (vBFR) resistance training has been shown to promote increases in muscle strength and size. Eccentric-only muscle actions are typically a more potent stimulus to increase muscle strength and size than concentric-only muscle actions performed at the same relative intensities. Therefore, the purpose...
Article
Full-text available
Hill, EC, Housh, TJ, Smith, CM, Keller, JL, Schmidt, RJ, and Johnson, GO. High- vs. low-intensity fatiguing eccentric exercise on muscle thickness, strength, and blood flow. J Strength Cond Res 35(1): 33-40, 2021-The purpose of this investigation was to examine the acute effects of equal volumes of fatiguing high- vs. low-intensity eccentric muscle...
Article
PURPOSE: To examine the changes in mechanomyographic (MMG) amplitude following 3 and 6 weeks of 80% vs. 30% one repetition maximum (1RM) resistance training in the leg extensors. METHODS: Twenty-six healthy men (23.1 ± 4.7 years; height = 180.6 ± 6.0 cm; weight = 80.0 ± 14.1 kg) participated in this randomized, repeated measures, between-group des...
Article
The mechanisms underlying velocity-specific decreases in torque production during eccentric muscle actions remain unclear. Therefore, the purpose of the present study was to examine electrical efficiency at 60 and 180°·s −1 during fatiguing, maximal eccentric isokinetic muscle actions of the leg extensors. Thirteen men visited the lab on two occasi...
Article
The purpose of the present investigation was to examine potential gender-related differences in electromyographic (EMG) and mechanomyographic (MMG) responses during submaximal, concentric, isokinetic, forearm flexion muscle contractions. Twelve men and twelve women performed concentric peak torque trials prior to (pretest) and following (posttest)...
Article
Full-text available
The purpose of this study was to examine sex-related differences in the accuracy of estimating actual target force and to compare the accuracy of estimating actual target force using percentages of maximal voluntary isometric contraction (MVIC) or ratings of perceived exertion (RPE) values during isometric leg flexion and leg extension muscle actio...
Article
Objective: Examine muscle-specific differences and the effects of fatigue and recovery on electromechanical delay (EMD) during maximal isokinetic muscle actions. Approach: Thirteen men performed maximal isokinetic knee extension muscle actions at 60ºs-1, pretest, posttest, and after 5-min of recovery from 25 maximal isokinetic knee extensions. Th...
Article
BACKGROUND: Little is known regarding the influence of force application during fatigue when the total amount of work is equal. That is, do changes in force applications result in different fatigue mechanisms despite the overall work being the same. OBJECTIVE: The aim of the current study was to examine the effects of alternating forces versus repe...
Article
This study used a combined electromyographic, mechanomyographic, and force approach to identify electromechanical delay (EMD) from the onsets of the electromyographic to force signals (EMDE-F), onsets of the electromyographic to mechanomyogrpahic signals (EMDE-M), and onsets of mechanomyographic to force signals (EMDM-F). The purposes of the curren...
Article
The purposes of this study were to examine: 1) the potential muscle-specific differences in voluntary electromechanical delay (EMD) and relaxation electromechanical delay (R-EMD), and 2) the effects of intensity on EMD and R-EMD during step incremental isometric muscle actions from 10 to 100% maximal voluntary isometric contraction (MVIC). EMD and...
Article
The purposes of the present study were to examine: 1) the effects of fatigue on electromechanical delay from the onsets of the electromyographic signal to force production (EMDE-F), the onsets of the electromyographic to mechanomyographic signals (EMDE-M), the onsets of the mechanomyographic signal to force production (EMDM-F), as well as the cessa...
Article
The purpose of the present study was to examine the effects of 2 different work-to-rest ratios, but the same mean load, cycle time, and total duration of the exercise bout, on maximal voluntary isometric contraction torque and neuromuscular responses to fatiguing, intermittent, submaximal, isometric, forearm flexion muscle actions. Ten men performe...
Article
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Purpose: The purposes of the present study were: (1) to determine whether the physical working capacity at the fatigue threshold (PWCFT) model that has been used for estimating the onset of neuromuscular fatigue in the vastus lateralis (VL) during incremental treadmill running could also be applied to the vastus medialis (VM), biceps femoris (BF),...
Article
Full-text available
We examined the neuromuscular adaptations following 3 and 6 weeks of 80% versus 30% one repetition maximum (1RM) resistance training to failure in the leg extensors. Twenty-six men (age = 23.1 ± 4.7 yrs) were randomly assigned to a high- (80% 1RM; n = 13) or low-load (30% 1RM; n = 13) resistance training group and completed leg extension resistance...
Article
The purpose of the current study was to examine the time course of changes in neuromuscular responses from the vastus medialis (VM) during low versus high intensity dynamic constant external resistance (DCER) leg extension muscle actions to failure. Thirteen men performed DCER leg extensions to failure at 30% and 70% 1-repetition maximum (1-RM) as...
Article
This study used a combined electromyographic, mechanomyographic, and force approach to identify electromechanical delay (EMD) from the onsets of the electromyographic to force signals (EMDE-F), onsets of the electromyographic to mechanomyogrpahic signals (EMDE-M), and onsets of mechanomyographic to force signals (EMDM-F). The purposes of the curren...
Article
The purpose of the present study was to examine the effects of electrode placements centered over and offset from the innervation zone (IZ) with different interelectrode distances (IED) on the time and frequency domain parameters of the electromyographic (EMG) signal during a fatiguing submaximal, isometric workout. 11 adults performed an isometric...
Article
BACKGROUND: It has been hypothesized [1] that the amplitude of the mechanomyographic (MMG) signal should track mean power output (MP) during dynamic muscle actions. Bodor's hypothesis has been supported in studies of non-fatigued muscles where MMG amplitude was shown to track velocity-related changes in MP, but not moment production, during concent...
Article
Introduction: The onsets of the electromyographic (EMG) signal, mechanomyographic (MMG) signal, and force production were used to identify voluntary electromechanical delay (EMD) during maximal and submaximal leg extensions. Methods: Twelve men performed 30% 1-repetition maximum concentric, dynamic constant external resistance leg extensions to...
Article
Full-text available
Objective To determine the effects of constant versus alternating applications of torque during fatiguing, intermittent isometric muscle actions of the leg extensors on maximal voluntary isometric contraction (MVIC) torque and neuromuscular responses. Methods Sixteen subjects performed two protocols, each consisting of 50 intermittent isometric mu...