SVEDENHAG, J. and J. SEGER. Running on land and in water: comparative exercise physiology. Med. Sci. Sports Exerc., Vol. 24, No. 10, pp. 1155-1160, 1992. The effect of water immersion on cardiorespiratory and blood lactate responses during running was investigated. Wearing a buoyant vest, 10 trained runners (mean age 26 yr) ran in water at four different and specified submaximal loads (target heart rates 115, 130, 145, and 155-160 beats[middle dot]min-1) and at maximal exercise intensity. Oxygen uptakes ([latin capital V with dot above]O2), heart rates, perceived exertion, and blood lactate concentrations were measured. Values were compared with levels obtained during treadmill running. For a given [latin capital V with dot above]O2, heart rate was 8-11 beats[middle dot]min-1 lower during water running than during treadmill running, irrespective of exercise intensity. Both the maximal oxygen uptake (4.03 vs 4.60 1[middle dot]min-1) and heart rate (172 vs 188 beats[middle dot]min-1) were lower during water running. Perceived exertion (legs and breathing) and the respiratory exchange ratio (RER) were higher during submaximal water running than during treadmill running, while ventilation (1-min-1) was similar. The blood lactate concentrations were consistently higher in water than on the treadmill, both when related to [latin capital V with dot above]O2 and to %[latin capital V with dot above]O2max. Partly in conformity with earlier cycle ergometer studies, these data suggest that immersion induces acute cardiac adjustments that extend up to the maximal exercise level. Furthermore, both the external hydrostatic load and an altered running technique may add to an increased anaerobic metabolism during supported water running.
(C)1992The American College of Sports Medicin
