Abstract

The intent of this investigation was to describe the effects of interval, front crawl swimming on muscle glycogen metabolism. The first phase of this research (Project A) examined the effects of interval training on the rate of glycogen use from the posterior deltoid muscle during repeated 100 (91.4 m) and 500 yd (457.2 m) bouts of front crawl swimming. The subjects swam a total distance of 6000 yd (5486 m) during each of these interval training sessions. A second study (Project B) examined the rate of glycogen resynthesis in the first eight hrs following a 3000 yd (2743 m) interval training session. During this eight-hr recovery period the subjects were fed a meal containing 112 g of carbohydrate. Significantly more muscle glycogen was used during the repeated 100 yd swims than during the 500 yd repetitions, demonstrating the effect of swimming intensity on the rate of muscle glycogen use. Histological examination of these muscle samples, however, revealed similar patterns of glycogen depletion from the type I and II fibers in both 100 and 500 yd interval sessions. The major finding of Project B was the relatively inadequate recovery of muscle glycogen during the eight-hr rest-feeding period that followed the 3000 yd training session (i.e. 6x500 yd; 1 rest). These data provide a better understanding of the impact of interval training on muscle glycogen reserves, and the risk of low muscle glycogen when swimmers train twice per day. Verf.-Referat