1 We hypothesized that either the recruitment of additional muscle motor units and/or progressive less efficient fast-twitch fibres was predominant contributor to oxygen 1uptake (V̇ O 2 ) observed during heavy exercise. Using surface electromyographic (EMG) techniques, we compared V̇ response with integrated EMG (iEMG) and mean power frequency (MPF) vastus lateralis repeated bouts moderate (below lactate threshold, <LT) (above >LT) intensity cycle ergometer Seven male subjects (age 29 ± 7...

This study examined the effect of heavy-intensity warm-up exercise on O 2 uptake (V˙o ) kinetics at onset moderate-intensity (80% ventilation threshold), constant-work rate in eight older (65 ± yr) and seven younger adults (26 1 yr). Step increases work from loadless cycling to moderate (Mod ), heavy exercise, were performed. Each bout was 6 min duration separated by cycling.V˙o modeled use a two-component exponential model. Heart (HR) using single During Mod , time constant (τ) for...

The effect of prior heavy-intensity warm-up exercise on subsequent moderate-intensity phase 2 pulmonary O uptake kinetics (τV̇o ) was examined in young adults exhibiting relatively fast (FK; τV̇o &lt; 30 s; n = 6) and slow (SK; &gt; V̇o without warm up. Subjects performed four repetitions a moderate (Mod 1 )-heavy-moderate protocol cycle ergometer with work rates corresponding to 80% estimated lactate threshold (moderate intensity) 50% difference between peak (heavy intensity); each...

Numerous studies have shown that stretching routines can induce strength and force deficits, although the amount of needed to cause these deficits remains unclear. Therefore, purpose study was examine relationship between varying amounts acute static on jumping performance. By systematically increasing stretching, possible differences in jump height may be discovered, defining a line where becomes detrimental Ten collegiate athletes 10 recreational completed 3 different treatments 1 control...

The aim of this study was to examine the effect skeletal muscle stretching on peripheral, central, and autonomic cardiovascular responses in humans. Twelve healthy males completed a controlled passive stretch plantar flexors for 4 min at three different intensities. Doppler ultrasound velocimetry imaging techniques assessed mean leg blood flow (MLBF), antegrade flow, retrograde popliteal artery. Near-infrared spectroscopy concentration deoxygenated hemoglobin + myoglobin ([HHb]) sum its...

Previous studies in isolated muscle preparations have shown that blood flow becomes compromised at higher contraction frequencies. The purpose of this study was to examine the effect increases frequency and tension on mean (MBF) during voluntary exercise humans. Nine male subjects [23.6 +/- 3.7 (SD) yr] performed incremental knee extension exhaustion supine position three frequencies [40, 60, 80 contractions/min (cpm)]. Mean velocity femoral artery determined beat by using Doppler...

To test for evidence of a muscle pump effect during steady-state upright submaximal knee extension exercise, seven male subjects performed discontinuous, incremental exercise stages (3 min/stage) at 40 contractions/min, work rates ranging to 60-75% peak aerobic rate. Cardiac cycle-averaged blood flow (MBF) responses and contraction-averaged were calculated from continuous Doppler sonography the femoral artery. Net contribution was estimated by difference between mean (MBFM) early recovery...

Abstract This study compared the muscular activation of pectoralis major, anterior deltoid and triceps brachii during a free‐weight barbell bench press performed at 0°, 30°, 45° –15° angles. Fourteen healthy resistance trained males (age 21.4 ± 0.4 years) participated in this study. One set six repetitions for each conditions 65% one repetition maximum were performed. Surface electromyography (sEMG) was utilised to examine selected muscles eccentric concentric phases. In addition, phase...

Previous studies suggest that women experience less vascular occlusion than men when generating the same relative contractile force. This study examined forearm blood flow (FBF) in and during isometric handgrip exercise requiring Thirty-eight subjects [20 18 men, 22.8 +/- 0.6 yrs old (means SE)] performed low- moderate-force on two occasions. Subjects five maximum voluntary contractions (MVC) before to determine 20% 50% MVC target forces. Time task failure (TTF) was determined subject could...

Skeletal muscle contractions are associated with physical stimuli that act upon vasculature, including increased shear stress and blood pressure. It is unclear if acute dynamic exercise alters local vascular function. The purpose of this study was to examine the role hemodynamics on effects function, as evaluated by brachial artery flow-mediated dilation (FMD). Healthy individuals (n = 14; age, 18–34 years) performed 30 min handgrip at fast slow contractions. Blood pressure during measured...

Summary The purpose of the investigation was to observe how varying occlusion durations affected neuromuscular activation and microvascular oxygenation during low‐volume isometric knee extension exercise. Healthy, recreationally active males performed at a variety submaximal intensities under different blood flow restriction ( BFR ) durations. pressure (130% SBP applied either 5 min prior exercise PO ), immediately IO or not CON ). Surface electromyography (s EMG near‐infrared spectroscopy...

Compared with moderate- and heavy-intensity exercise, the adjustment of O 2 uptake (V̇o ) to exercise intensities that elicit peak V̇o has received relatively little attention. This study examined response 21 young, healthy subjects (25 ± 6 yr; mean SD) during cycle ergometer step transitions in work rate (WR) corresponding 90, 100, 110% WR achieved a preliminary ramp protocol (15-30 W/min). Gas exchange was measured breath by interpolated 1-s values. kinetics were determined use two- or...

The [H + ] and [HCO 3 − of biological solutions is determined by the [Formula: see text], concentration strong ions (mainly Na , K Ca 2+ Cl lactate ), weak acids proteins, phosphates). Two mathematical models are available that use a quantitative approach to describe acid–base behaviour plasma, but which differ in their treatment acid component: Stewart model (using ion difference (SID = [Na [Cl ]) [protein] TOT ); Fencl SID, [albumin], [P i ). present study compared measured estimated...

This study examined the relationship between muscle recruitment patterns using surface electromyography (EMG) and excess O 2 uptake (ExV̇ O2 ) that accompanies slow (SR, 8 W min −1 but not fast (FR, 64 ramp increases in work rate (WR) during exercise on a cycle ergometer. Nine subjects (2 females) participated this (25 ± years, S.E.M.). EMG was obtained from vastus lateralis medialis analysed time (root mean square, RMS) frequency (median power frequency, MDPF) domain. Results for each were...

To test the hypothesis that sex influences forearm blood flow (FBF) during exercise, 15 women and 16 men of similar age [women 24.3 +/- 4.0 (SD) vs. 24.9 4.5 yr] but different muscle strength (women 290.7 44.4 509.6 97.8 N; P < 0.05) performed dynamic handgrip exercise as same absolute workload was increased in a ramp function (0.25 W/min). Task failure defined inability to maintain contraction rate. Blood pressure FBF were measured on separate arms by auscultation Doppler ultrasound,...

Muscle damage is a common response to unaccustomed eccentric exercise; however, the effects of skeletal muscle on local vascular function and blood flow are poorly understood. This study examined serial responses flow-mediated (endothelial-dependent) nitroglycerin-mediated (endothelial-independent) dilation in brachial artery after strenuous exercise serially assessed resting flow. Ten healthy males performed 50 maximal unilateral arm contractions induce biceps brachii. Changes isometric...

MALLORY, L. A., B. W. SCHEUERMANN, D. HOELTING, M. WEISS, R. MCALLISTER, and T. J. BARSTOW. Influence of peak V̇O2 muscle fiber type on the efficiency moderate exercise. Med. Sci. Sports Exerc., Vol. 34, No. 8, pp. 1279–1287, 2002. Purpose The purpose this study was to determine if %Type I fibers and/or aerobic fitness (as V̇O2) would predict Δ (ΔEff) ΔV̇O2/Δwork rate (WR) for (below lactate threshold <LT) constant work exercise in subjects with diverse level type. Methods Twenty-two (15...

Purpose: The purpose of the present study was to determine whether gender differences are in fatigability inspiratory muscles humans. Based on evidence for a difference oxygen cost breathing, we hypothesized that females would result greater magnitude and/or faster rate muscle fatigue than males. Methods: Eleven and males (N = 22) performed resistive breathing at target pressure 70% maximal (PImax). Rate calculated from measures PImax taken every 2 min during recovery strength assessed up 45...