Running and Breathing in Mammals
Dennis M. Bramble and David R. Carrier
The capacity for sustained aerobic exercise (locomotion) is characteristic of
both birds and mammals and has no doubt contributed to their evolutionary
success. Mammalian locomotion in particular has been the object of intense
investigation in recent years. Studies have been done to elucidate the characteristic movement patterns or "gaits"
employed by various species (1, 2) as well as their biomechanical (3-5) and energetic (6) bases. Nonetheless, one basic aspect of mammalian locomotion has gone almost entirely without notice-namely, the manner in which mammals integrate respiration and locomotion. It is obvious, for example, that running mammals must effectively ventilate their lungs while in motion if sustained aerobic metabolism is to be achieved. But exactly how pulmonary function is accomplished under such conditions and to what extent body motion influences the respiratory process-have not been determined by those concerned either with locomotor or respiratory phenomena. It now appears, however, that locomotor-respiratory integration must be included in any realistic evaluation of the form,function, and evolution of mammalian locomotor and respiratory mechanisms.
Most of the evidence favoring an intrinsic linkage between locomotion and respiration in mammals has come from
physiological experiments on anesthesized, decerebrate laboratory animals and from bicycle ergometer tests on humans. Early observations suggested that movement of the limbs could evoke changes in the breathing of anesthesized mammals (7). Subsequent studies have yielded many additional data in support of the neurogenic control of the respira-
Dr. Bramble is associate professor in the Depart-
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