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Dynamics of skeletal muscle oxygenation during sequential bouts of moderate exercise
Author(s) -
Ferreira Leonardo F.,
Lutjemeier Barbara J.,
Townsend Dana K.,
Barstow Thomas J.
Publication year - 2005
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2004.029595
Subject(s) - skeletal muscle , dynamics (music) , medicine , oxygenation , exercise physiology , cardiology , physical medicine and rehabilitation , psychology , pedagogy
In rat muscle, faster dynamics of microvascular P O2 (approximately blood flowto O 2 uptakeratio) after prior contractions that did not alter blood [lactate] have been considered to be a consequence of fasterkinetics. However, in humans, prior exercise below the lactate threshold does not affect the pulmonarykinetics. To clarify this apparent discrepancy, we examined the effects of prior moderate exercise on the kinetics of muscle oxygenation (deoxyhaemoglobin, [HHb]α) and pulmonaryin humans. Eight subjects performed two bouts (6 min each) of moderate‐intensity cycling separated by 6 min of baseline pedalling. Muscle (vastus lateralis) oxygenation was evaluated by near‐infrared spectroscopy andwas measured breath‐by‐breath. The time constant (τ) of the primary component ofwas not significantly affected by prior exercise (21.5 ± 9.2 versus 25.6 ± 9.7 s; Bout 1 versus 2, P = 0.49). The time delay (TD) of [HHb] decreased (11.6 ± 2.6 versus 7.7 ± 1.5 s; Bout 1 versus 2, P < 0.05) and τ[HHb] increased (7.0 ± 3.5 versus 10.2 ± 4.6 s; Bout 1 versus 2, P < 0.05), while the mean response time (TD +τ) did not change (18.6 ± 2.7 versus 17.9 ± 3.9 s) after prior moderate exercise. Thus, prior moderate exercise resulted in shorter onset and slower rate of increase in [HHb] during subsequent exercise. These data suggest that prior exercise altered the dynamic interaction betweenandfollowing the onset of exercise.