Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
from September 2014
©Journal of Sports Science and Medicine (2012) 11, 759 - 767

Research article
The Contribution of "Resting" Body Muscles to the Slow Component of Pulmonary Oxygen Uptake During High-Intensity Cycling
Fadil Ozyener1,2, , Brian J. Whipp (deceased)*1,3,*, Susan A. Ward1,3
Author Information
1 Department of Physiology, St George’s Hospital Medical School, London
2 Department of Physiology, Uludag University Medical School, Bursa, Turkey
3 Human Bio-Energetics Research Centre, Crickhowell, Powys, UK

Fadil Ozyener
✉ Department of Physiology, Uludag University Medical School, 16059 Bursa, Turkey
Publish Date
Received: 07-01-2012
Accepted: 30-04-2012
Published (online): 01-12-2012
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Oxygen uptake (VO2) kinetics during moderate constant-workrate (WR) exercise (>lactate-threshold (θL)) are well described as exponential. AboveθL, these kinetics are more complex, consequent to the development of a delayed slow component (VO2sc), whose aetiology remains controversial. To assess the extent of the contribution to the VO2sc from arm muscles involved in postural stability during cycling, six healthy subjects completed an incremental cycle-ergometer test to the tolerable limit for estimation of θL and determination of peak VO2. They then completed two constant-WR tests at 90% of θL and two at 80% of ∆ (difference between θL and VO2peak). Gas exchange variables were derived breath-by-breath. Local oxygenation profiles of the vastus lateralis and biceps brachii muscles were assessed by near-infrared spectroscopy, with maximal voluntary contractions (MVC) of the relevant muscles being performed post-exercise to provide a frame of reference for normalising the exercise-related oxygenation responses across subjects. Above supra-θL, VO2 rose in an exponential-like fashion ("phase 2), with a delayed VO2sc subsequently developing. This was accompanied by an increase in [reduced haemoglobin] relative to baseline (∆[Hb]), which attained 79 ± 13 % (mean, SD) of MVC maximum in vastus lateralis at end-exercise and 52 ± 27 % in biceps brachii. Biceps brachii ∆[Hb] was significantly correlated with VO2 throughout the slow phase. In contrast, for sub- L exercise, VO2 rose exponentially to reach a steady state with a more modest increase in vastus lateralis ∆[Hb] (30 ± 11 %); biceps brachii ∆[Hb] was minimally affected (8 ± 2 %). That the intramuscular O2 desaturation profile in biceps brachii was proportional to that for VO2sc during supra-θL cycle ergometry is consistent with additional stabilizing arm work contributing to the VO2sc.

Key words: Muscle oxygenation, near infrared spectroscopy, oxygen uptake kinetics, arm exercise

           Key Points
  • The source(s) of the "slow component" component of pulmonary oxygen uptake kinetics (VOsc) associated with high-intensity exercise remains the source of debate.
  • Noninvasive interrogation techniques of the biceps brachii muscle during cycle ergometry suggest that "resting" muscles, such as those of the arms and shoulder girdle, may contribute to the VOsc, through stabilising actions (e.g. more forceful pulling on the ergometer handlebars).
  • The quantitative contribution of such extra "resting"-muscle work awaits precise determination.
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