Piyarit Srikeau. Physiological and psychological responses to ingested water of different temperatures during prolonged exercise and recovery periods . Master's Degree(Sports Science). Mahidol University. : Mahidol University, 2004.
Physiological and psychological responses to ingested water of different temperatures during prolonged exercise and recovery periods
Abstract:
The objectives of this study were to compare physiological and psychological
responses to ingested water of different temperatures during prolonged exercise and
recovery periods. Ten healthy male volunteers with an average age of 20.30±0.74 years
performed an experiment with three periods (rest, exercise at 60% VO2max and recovery)
on a cycle ergometer under four conditions with a random order of water ingestion
[no water, cool water (4±1°C), room temperature water (25±1°C), and warm water
(37±1°C)]. The temperature and humidity of laboratory were controlled at 25°C and
50-60%, respectively to measure physiological and psychological responses during
prolonged exercise and recovery periods. Room temperature water was ingested 5 ml/kg
body weight (BW) at rest, to standardize pre-hydration status (all trails). After rest for 20
minutes, subjects started exercise and 5 ml/kg water of different temperatures were
ingested immediately before exercise, and every 15 minutes during exercise (15th, 30th,
45th, and 60th minutes) in every trial (except no water trial). The physiological and
psychological responses were measured and recorded at five-minute intervals until the
end of the experiment. The level for statistical difference was set at p<0.05.
No significant advantage of water ingestion was found at any temperature during
exercise of less than 30th min duration. However, the cool water ingestion (4±1°C) can
significantly decrease rectal (core) temperature while increase blood pressure, tidal
volume, respiratory rate, minute ventilation, and respiratory flow (p<0.05) when
compared to no water, room temperature water (25±1°C), and warm water (37±1°C)
ingestion. Cool water can, induce headaches if the subject drinks too much in a short
time, cause the production of more urine during exercise, and use more calories at the
onset of exercise when compared to other water temperatures. Room temperature water
ingestion (25±1°C) has shown to be the best for use during prolonged exercise in a
neutral environment because it significantly changes all physiological and psychological
responses in the same way as cool water does without side effects. However, warm water
ingestion (37±1°C) was not appropriate for use during prolonged exercise because it has
shown less effective to decrease rectal (core) temperature in neutral environment and
also results in an increased heart rate, and sweating rate that can affect prolonged
exercise performance