This study examined changes of swimming velocity (V), stroke rate (SR) and stroke length (SL) in 5m intervals over all stroke phases of a 200-m freestyle swimming race (1997 Japanese championships). These stroke variables, analyzed using images from five VHS video cameras, were compared between elite (finalists: FM; 8 male, FF; 8 female) and sub-elite (slowest of preliminary race : LM ; 8 male, LF; 5 female)groups. Velocity was highest at first 5-m section of the first stroke phase in all groups. Velocity then gradually decreased until the middle of the second stroke phase. From the middle of the second phase, the elite group V remained unchanged while the sub-elite V decreased until the end of the fourth stroke phase. Stroke length change pattems were similar in all groups, showing peaks at the middle of the second stroke phase, and decreasing gradually to end of the fourth stroke phase. Stroke rates were found to change similarly with V until the middle of the second stroke phase after which the elite SR gradually increased while the sub-elite SR remained unchanged until the end of the fourth stroke phase. These results suggest that the changes in V between elite and sub-elite groups was mainly caused by changes in SR, and that favorable performance in the 200-m freestyle can be elicited by increasing the SR from the middle of the second stroke phase.
