The purpose of this experiment was to examine the effects of the endogenous opioid system on forearm muscle pain and muscle sympathetic nerve activity (MSNA) during dynamic fatiguing exercise. Twelve college-age men (24 +/- 4 yr) performed graded (1-min stages; 30 contractions/min) handgrip to fatigue 1 h after the ingestion of either 60 mg codeine, 50 mg naltrexone, or placebo. Pain (0-10 scal...

During motor preparation, the attention is paid more and more frequently to the complex significance of fatigue in the case of the achieved sport outcome. The complexity of this process has not been utterly explained so far. It is important to acquire the profound knowledge about the central and peripheral fatigue while explaining this mechanism, because they remain in the background of the hum...

Optic flow on the retina creates a perception of a person's movement relative to their surroundings. This study investigated the effect of optic flow on perceived exertion during cycling. Fifteen participants completed a 20-km reference cycling time trail in the fastest possible time followed by three randomly counterbalanced 20-km cycling trials. Optic flow, via projected video footage of a cy...

Prolonged lifting may be associated with an incrase injury risk due to fatigued muscles being less capable of reacting to any perturbations that occur during a lift. Repetitive muscle use leads to reduced functional capacity, known as fatigue. In lower force tasks, fatigue is an ongoing process which may result in increased perceived effort and a reduction in the maximal force generating capaci...

Purpose: To quantify the mean daily changes in training and match load and any parallel changes in indicators of morning-measured fatigue across in-season training weeks in elite soccer players. Methods: Following each training session and match, ratings of perceived exertion (s-RPE) were recorded to calculate overall session load (RPE-TL) in 29 English Premier League players from the same team...

It has been shown that the mental fatigue induced by prolonged self-regulation increases perception of effort and reduces performance during subsequent endurance exercise. However, the physiological mechanisms underlying these negative effects of mental fatigue are unclear. The primary aim of this study was to test the hypothesis that mental fatigue exacerbates central fatigue induced by whole-...

BACKGROUND Slow walking speed in elderly people predicts increased morbidity and mortality. We examined factors that may be associated with decreased habitual walking speed in older men and women. METHODS Older (range: 60-88 years, mean = 72.5 years) men (n = 25) and women (n = 24) were recruited. The Short Physical Performance Battery, body composition, VO(₂peak) on a treadmill, VO₂ and rate...

We previously demonstrated that nonfatiguing rhythmic forearm exercise at 25% maximal voluntary contraction (12 2-s contractions/min) evokes sympathoexcitation without significant engagement of metabolite-sensitive muscle afferents (B.A. Batman, J.C. Hardy, U.A. Leuenberger, M.B. Smith, Q.X. Yang and L.I. Sinoway. J. Appl. Physiol. 76: 1077-1081, 1994). This is in contrast to the sympathetic ne...

The effectiveness of selected physiological and perceptual measures for monitoring training load and fatigue was studied in 16 male elite rugby sevens players during a 6-week intense training block (IT) and 2-week tapering (TAP). Daily training load (TL) and strain (TS) as well as weekly total score of fatigue (TSF) were quantified respectively by the session-rating of perceived exertion (RPE) ...