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Am J Physiol Regul Integr Comp Physiol 297: R615-R621, 2009. First published June 17, 2009; doi:10.1152/ajpregu.00048.2009
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ARTICLES

Effects of prior heavy exercise on heterogeneity of muscle deoxygenation kinetics during subsequent heavy exercise

Tadashi Saitoh,1 Leonardo F. Ferreira,2 Thomas J. Barstow,3 David C. Poole,3 Anna Ooue,4 Narihiko Kondo,4 and Shunsaku Koga5

1Graduate School of Science and Engineering, Yamagata University, Yonezawa, Japan; 2Department of Physiology, University of Kentucky, Lexington, Kentucky; 3Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas; 4Graduate School of Cultural Studies and Human Science, Kobe University, Kobe; and 5Applied Physiology Laboratory, Kobe Design University, Kobe, Japan

Submitted 23 January 2009 ; accepted in final form 11 June 2009

We investigated the effects of prior heavy exercise on the spatial heterogeneity of muscle deoxygenation kinetics and the relationship to the pulmonary O2 uptake (pVO2) kinetics during subsequent heavy exercise. Seven healthy men completed two 6-min bouts of heavy work rate cycling exercise, separated by 6 min of unloaded exercise. The changes in the concentration of deoxyhemoglobin/myoglobin ({Delta}deoxy-[Hb+Mb]) were assessed simultaneously at 10 different sites on the rectus femoris muscle using multichannel near-infrared spectroscopy. Prior exercise had no effect on either the time constant or the amplitude of the primary component pVO2, whereas it reduced the amplitude of the slow component (SC). {Delta}Deoxy-[Hb+Mb] across all 10 sites for bout 2 displayed a shorter time delay (mean and SD for subjects: 13.5 ± 1.3 vs. 9.3 ± 1.4 s; P < 0.01) and slower primary component time constant ({tau}: 9.3 ± 1.3 vs. 17.8 ± 1.0 s; P < 0.01) compared with bout 1. Prior exercise significantly reduced both the intersite coefficient of variation (CV) of the {tau} of {Delta}deoxy-[Hb+Mb] (26.6 ± 11.8 vs. 13.7 ± 5.6%; P < 0.01) and the point-by-point heterogeneity [root mean square error (RMSE)] during the primary component in the second bout. However, neither the change in the CV for {tau} nor RMSE of {Delta}deoxy-[Hb+Mb] correlated with the reduction in the SC in pVO2 kinetics during subsequent heavy exercise. In conclusion, prior exercise reduced the spatial heterogeneity of the primary component of muscle deoxygenation kinetics. This effect was not correlated with alterations in the pVO2 response during subsequent heavy exercise.

near-infrared spectroscopy; spatial heterogeneity; oxygen uptake kinetics; muscle oxygen delivery


Address for reprint requests and other correspondence: S. Koga, Applied Physiology Laboratory, Kobe Design Univ., 8-1-1 Gakuennishi-machi, Nishi-ku, Kobe, 651-2196 Japan (e-mail: s-koga{at}kobe-du.ac.jp)






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