The present study investigated the difference in metabolic responses to exercise intensity and duration between arm cranking and leg cycling, to clarify the effectiveness of arm exercise in fat combustion. During each experiment, oxygen uptake (VO₂) and respiratory exchange ratio (RER) were monitored. Near-infrared spectroscopy was used to measure changes in muscle deoxygenation in the triceps during arm cranking as well as in the vastus lateralis during leg cycling. (Experiment 1) Twenty-seven females completed incremental arm cranking and leg cycling tests. During arm cranking, there was a rapid increase in the RER, and a lower lactate threshold, as compared with leg cycling. In addition, muscle deoxygenation during arm cranking rose up to the middle of VO₂ peak (mean 51.4%). These results suggest that the oxygen demand in the triceps reached a maximum. (Experiment 2) Ten females performed three-intermittent 10-min arm cranking and leg cycling sessions at 20, 40, and 60% of the mode-specific maximal workload. RER at steady state was significantly higher during arm cranking than during leg cycling at all intensities. (Experiment 3) Four females performed 60-min arm cranking and leg cycling at 40% of the mode-specific VO₂ peak. Both modes showed similar response for RER, namely, gradual decrease from the 10-15th min until the end of exercise. At the beginning of arm cranking, however, temporary increase in RER and promotion of muscle deoxygenation were observed. In conclusion, the results of the present study suggest that anaerobic glycolytic metabolism is easily promoted during arm exercise, compared with leg cycling, especially at the beginning of exercise.

DESCENTE SPORTS SCIENCE Vol.24/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE