Stretching, as a warm-up procedure has previously been used to prepare a muscle for strenuous activity. Recently stretching has been shown to actually reduce the force producing capacity of a muscle and as a result caused decrements in physical performances. Since stretching is traditionally used as a measure to prepare the musculature for physical training in competitive swimmers we sought to determine whether stretching would cause decrements in the training performances of competitive swimmers. Informed consent was obtained from 16 volunteers who had been training more than 60 km x wk-1 for a period of 6 wk completed this study. The swimmers were divided into two groups and performed the stretching protocol on one of two different days separated by 13 days of regular training. The assignments were counter balanced. On the assigned stretching (STRWU) day the swimmer performed a 12 min directed stretching protocol that included each major muscle group prior to swimming a set of 6x100 m efforts with a 10 min rest between efforts. On the control day (CONWU) each swimmer performed their normal warm-up prior to starting the same training set. Times were recorded on a Colorado Automatic Timing System and recorded in seconds for statistical analysis. We used a Fixed Factor 2 x 2 (subject) day by condition) Analysis of Variance to determine the effects of stretching on the training performances of competitive swimmers. The times (Mean + SEM) for day 1 were STRWU (65.87+1.11) and CONWU (69.58+.94) seconds and for day 2 times were STRWU (70.38+.61) and CONWU (68.83+.9). There were no significant differences between the experimental conditions (P>.05) and between the days on which the experimental conditions were administered (P>.05). There was no significant interaction (day by condition) (P>.05). We concluded that in the case of the first effort of training sets stretching did not impact training performances of competitive swimmers. We recommend this protocol be repeated using a single short explosive effort done under competitive conditions to determine whether stretching during warm-up impacts competitive performance.