Ten moderately trained male swimmers volunteered to take part in the present study. They were divided into two groups: five swimmers swam the front crawl stroke (crawl stroke group) and a group of five swam the breaststroke (breaststroke group). All subjects swam wearing conventional swimsuits, typically used by competitive swimmers (swimsuit); they also wore training shirts, pants, and shoes (training clothes). Both groups would swim as fast as they could for 60 seconds, first wearing training clothes and then wearing swimsuits. The swimming speed, the stroke rates, the distance covered per stroke, the heart rate and oxygen intakes were measured during each swimming period. Peak ammonia and lactate concentrations in the blood were measured after each swimming exercise, wearing a swimsuit and training clothes. This study demonstrated that the average speed decreased considerably when the subjects wore training clothes compared to wearing swimsuits in both the crawl stroke and breaststroke groups. The average swimming speed wearing training clothes decreased much more in the crawl stroke than in the breaststroke in comparison with wearing swimsuits. The stroke rate of swimmers wearing training clothes were lower than those wearing swimsuits in the crawl stroke, however, there was no significant stroke difference found in the breaststroke. The distance covered per stroke of those wearing training clothes was shorter than those wearing swimsuits in the crawl stroke and the breaststroke. Both the heart rate and the oxygen uptake during the swimming exercise were not significantly different between those subjects wearing training clothes and swimsuits in the crawl stroke and in the breaststroke. The peak blood ammonia and lactate concentrations after swimming with swimsuits were significantly higher than with training clothes in the crawl stroke. However, there were no significant differences in the blood ammonia and lactate concentrations between swimmers wearing training clothes and swimsuits in the breaststroke.
　These findings demonstrated that the decrease of the average speed in the crawl stroke wearing training clothes might be due to the decrease in the stroke rate and distance per stroke. It could also be explained by the decrease of glycogen break down and the Purine nucleotide degradation.

DESCENTE SPORTS SCIENCE Vol.19/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE