Effect of water temperature on performance, lactate production and heart rate at swimming of maximal and submaximal intensity.

The effect of water temperature on performance effort, monitored heart rate and lactate production during freestyle swimming at maximal and submaximal speed has been studied. Fifteen male sprint swimmers performing 100 m swimming and fifteen comparable endurance competitors performing 30 min swimming at submaximal speed served as subjects. Water temperature in separate events was 20, 26 and 32 degrees C. At maximal performance there was a direct relationship between any two of the following parameters: water temperature, average swimming speed, heart rate during the competition and plasma lactate concentration after the event. Thus, the best effort (speed 1.704 m/s), the highest peak heart rate (185 beats/min) and the highest lactate level (19.8 mmol/l) were observed at 32 degrees C (all mean values). In contrast, these values were markedly lower at 20 degrees C. At the submaximal effort, water temperature was related to peak heart rate only. The highest peak heart rate (144 beats/min) was again obtained at 32 degrees C, while the lactate concentration (4.2-5.2 mmol/l) was independent of temperature. Water temperature appears to have a direct effect on performance effort, heart rate and lactate production during swimming at maximal intensity, whereas this effect seems to fade at submaximal efforts.