Abstract.
The aim of this investigation was to examine the effect of water ingestion on physiological responses to prolonged cycling (CYC) and running (RUN). A group of 11 men with mean (SEM) maximal oxygen uptake (V˙O2max) 48.5 (1.8) ml·kg–1·min–1 on a cycle-ergometer and 52.1 (2.2) ml·kg–1·min–1 on a treadmill (P<0.01) exercised for 90 min on four occasions, twice on each ergometer, at 60% of mode specific V˙O2max. No fluid was taken (D) in one trial on each ergometer, whereas 60% of fluid losses were replaced by drinking water in the other trial (W). In CYC, water ingestion attenuated the change in cardiac output (\(\Delta {\rm \dot Q}_{\rm c} \) ) and the reduction in stroke volume (ΔSV) [ΔSV: –22.7 (3.8) in D, –10.7 (2.9) ml·beat–1 in W, P<0.01; \(\Delta {\rm \dot Q}_{\rm c} \) : –1.9 (0.5) in D, –0.2 (0.4) l·min–1 in W at 85 min, P<0.01], but did not affect rectal temperature [T re at 90 min: 38.8 (0.1)°C in D, 38.7 (0.1)°C in W]. In contrast, fluid replacement reduced hyperthermia in RUN [T re at 90 min: 39.6 (0.2) in D, 39.1 (0.2)°C in W, P<0.01], and this was linked with a higher skin blood flow [RUN-W 88.9 (8.5), RUN-D 70.7 (8.4)%, P<0.05]. The \(\Delta {\rm \dot Q}_{\rm c} \) and ΔSV were also attenuated with water ingestion in this mode of exercise (P<0.05). It is concluded that water ingestion improves physiological function in both cycling and running, but that the underlying mechanism is different in the two modes of exercise.
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Nassis, G.P., Geladas, N.D. Effect of water ingestion on cardiovascular and thermal responses to prolonged cycling and running in humans: a comparison. Eur J Appl Physiol 88, 227–234 (2002). https://doi.org/10.1007/s00421-002-0682-5
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DOI: https://doi.org/10.1007/s00421-002-0682-5