Prolonged constant load cycling exercise is associated with reduced gross efficiency and increased muscle oxygen uptake

Hopker, James G. and OGrady, Ciaran and Pageaux, Benjamin (2016) Prolonged constant load cycling exercise is associated with reduced gross efficiency and increased muscle oxygen uptake. Scandinavian journal of medicine & science in sports, 27 (4). pp. 408-417. ISSN 1600-0838. (doi:https://doi.org/10.1111/sms.12673) (Full text available)

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Abstract

This study investigated the effects of prolonged constant load cycling exercise on cycling efficiency and local muscle oxygen uptake responses. Fourteen well-trained cyclists each completed a 2-h steady-state cycling bout at 60% of their maximal minute power output to assess changes in gross cycling efficiency (GE) and muscle oxygen uptake (mVO2) at time points 5, 30, 60, 90, and 120 min. Near-infrared spatially resolved spectroscopy (NIRS) was used to continually monitor tissue oxygenation of the Vastus Lateralis muscle, with arterial occlusions (OCC) applied to assess mVO2 . The half-recovery time of oxygenated hemoglobin (HbO2 ) was also assessed pre and post the 2-h cycling exercise by measuring the hyperemic response following a 5-min OCC. GE significantly declined during the 2-h cycling bout (18.4 ± 1.6 to 17.4 ± 1.4%; P < 0.01). Conversely, mVO2 increased, being significantly higher after 90 and 120 min than at min 5 (+0.04 mlO2 /min/100 g; P = 0.03). The half-recovery time for HbO2 was increased comparing pre and post the 2-h cycling exercise (+7.1 ± 19s), albeit not significantly (d: 0.48; P = 0.27). This study demonstrates that GE decreases during prolonged constant load cycling exercise and provides evidence of an increased mVO2 , suggestive of progressive mitochondrial or contractile inefficiency.

Item Type: Article
Uncontrolled keywords: Cycling efficiency;lactate threshold;maximal oxygen uptake;endurance performance;muscle efficiency
Subjects: G Geography. Anthropology. Recreation > GV Recreation Leisure > Sports sciences
R Medicine > RC Internal medicine > RC1235 Physiology of sports
Divisions: Faculties > Sciences > School of Sport and Exercise Sciences
Depositing User: James Hopker
Date Deposited: 25 May 2016 19:44 UTC
Last Modified: 21 Nov 2017 12:19 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/55697 (The current URI for this page, for reference purposes)
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