Muscle Oxidative Capacity in the Arms and Legs of Various Types of Endurance Trained Athletes

Our study used near-infrared spectroscopy (NIRS) to measure muscle oxidative capacity (mVmax) in the medial gastrocnemius, vastus lateralis, biceps brachii, and wrist flexor muscles in Cross-country (LEG-T) and Swimmer/Rowers (WHOLE-T) and controls. Young male adults: cross-country LEG-Tners (n=6) and swimmers/rowers (n=5), moderately fit (CONTROL, n=7) were tested. mVmax was measured as the rate of post-exercise recovery of oxygen consumption after a short bout of exercise using NIRS. Whole-body peak oxygen uptake (VO2peak) was determined during a continuous treadmill protocol. The lower limb muscles had 42% higher mVmax than upper limb muscles in all subjects, with significant differences in 10 of 12 pairwise comparisons (p< 0.05). The LEG-T group had higher mVmax values in both legs than CONTROL group (p< 0.05), while the WHOLE-T group had higher mVmax in the vastus lateralis (p = 0.048). There were no differences in the arm muscles of between the groups. The combined mVmax of both leg muscles in all groups correlated with VO2peak (r2=0.597). Muscle oxidative capacity was consistent with training status, and leg mitochondrial capacity correlated with maximal whole body oxidative capacity. These results support the use of NIRS measurements to characterize oxidative capacity in skeletal muscles of athletic populations.