title: Locomotor Muscle Fatigue Does Not Alter Oxygen Uptake Kinetics during High-Intensity Exercise.
abstract: The [Formula: see text] slow component ([Formula: see text]) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min-1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and [Formula: see text] determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P= 0.03), the [Formula: see text] was not significantly different between the pre-fatigue (464 ± 301 mL·min-1) and the control (556 ± 223 mL·min-1) condition (P= 0.50). Blood lactate response was not significantly different between conditions (P= 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P< 0.01) suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the [Formula: see text] kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the [Formula: see text] is strongly associated with locomotor muscle fatigue.
authors: Endurance Research Group, School of Sport and Exercise Sciences, University of Kent Chatham, UK.
authors: James G
authors: JG
authors: Hopker
authors: Endurance Research Group, School of Sport and Exercise Sciences, University of KentChatham, UK; Applied Sport Science Research Group, School of Health, Sport and Bioscience, University of East LondonLondon, UK.
authors: Giuseppe
authors: G
authors: Caporaso
authors: Endurance Research Group, School of Sport and Exercise Sciences, University of KentChatham, UK; Leicester City Football ClubLeicester, UK.
authors: Andrea
authors: A
authors: Azzalin
authors: Applied Sport Science Research Group, School of Health, Sport and Bioscience, University of East London London, UK.
authors: Roger
authors: R
authors: Carpenter
authors: Endurance Research Group, School of Sport and Exercise Sciences, University of Kent Chatham, UK.
authors: Samuele M
authors: SM
authors: Marcora
keywords: aerobic exercise; cycling; efficiency; locomotor muscle fatigue; power output; slow component