Effect of water ingestion on cardiovascular and thermal responses to prolonged cycling and running in humans: a comparison |
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Authors: | Nassis George P Geladas Nickos D |
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Institution: | (1) Department of Sport Medicine and Biology of Physical Activity, Faculty of Physical Education and Sport Science, University of Athens, 41, Ethnikis Antistassis Street, 172 37, Daphne, Greece, |
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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 (
) 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;
: –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
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.
Electronic Publication |
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Keywords: | Fluid replacement Hyperthermia Stroke volume Cycling Running |
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