MUSCLE OXYGENATION HETEROGENEITY IN A SINGLE MUSCLE AT REST AND DURING BICYCLE EXERCISE(Proceedings of The 8^<th> Asian Federation of Sports Medicine Congress 2005 Tokyo)

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We evaluated regional differences of muscle O_2 dynamics between distal and proximal sites in the vastus lateralis (VL) muscle using near infrared spatial resolved spectroscopy (NIR_<SRS>). forty-one male subjects performed a 30W ramp incremental bicycle exercise test until exhaustion. The NIR_<SRS> probes were attached on each distal and proximal site in the VL. The pulmonary O_2 uptake and heart rate were monitored continuously during the experiment. The TOI at rest was significantly higher in proximal than distal sites (65.0±5.2 vs. 69.7±4.6%, p<0.001). The TOI at exhaustion was also significantly higher in proximal than distal sites (39.5±6.7 vs. 47.5±7.6%, p<0.001). Moreover, a significant correlation was found between VO_2max and the TOI at exhaustion in each proximal and distal site in the VL. Half time reoxygenation, the time to reach a value of half-maximal recovery, was significantly slower in distal sites than proximal sites (27.1±5.6 vs. 25.0±6.1 sec, p<0.01). In conclusion, lower muscle oxygenation at exhaustion in higher VO_2max may be due to enhanced O_2 extraction in high oxidative capacity muscle. In addition, slower reoxygenation and lower muscle deoxygenation at the distal site in the VL may be explained by differences in O_2 supply and/or muscle fiber composition between distal and proximal sites.
2006-10-01