Work Efficiency and Respiratory Response of Trained Underwater Swimmers Using a Modified Self-Contained Underwater Breathing Apparatus

¹ From the National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Maryland

Studies of the work efficiency and respiratory responses of trained underwater swimmers were made employing a modified self-contained underwater breathing apparatus (SCUBA). It was found that the work efficiencies were very low (2–8%) as compared to the efficiencies of comparable exercises in air (16– 20%). At low swim speeds (.6 and .7 knots) average efficiencies from swimmer to swimmer varied markedly (2–8%) while at higher swim speeds (.7–1.2 k.) the average efficiencies varied little (3–5%). The maximum attainable respiratory responses to an extended exercise period (20 min.) in underwater swimming were much lower than those observed in exercises in air. Thus, maximum pulmonary minute volumes were usually much less than 80 liters and the maximum oxygen consumption was only about 100 liters per square meter body surface per hour.