The purpose of this study was to examine the association of determinants of the change of direction sprint. In relation with leg extension power and selective reaction time. Subjects were collegiate male soccer players. Sprint times with or without change of direction (turning backwards, right or left side) were performed either in unanticipated or preplanned conditions in which the instruction of turning direction was known or hidden to the participants prior to the trial. Maximal Leg extension power and reaction times in the preplanned and unanticipated conditions were also measured using an isokinetic strength measurement system and a visual stimulus system, respectively. Both sprint times with or without change of direction in the unanticipated condition were longer than those in the preplanned condition directions. Cronbach's α was less than 0.70, indicating that sprint times in the unanticipated condition were not interchangeable with those in the preplanned codition. The differences in the sprint times between both conditions were not significantly related to the selective reaction times. Sprint times with or without change of direction in the unanticipated condition were significantly associated with leg extension power relative to body mass, and the corresponding relationships differed from those in the preplanned one. The current results indicate that (1) the determinants of change of direction in the unanticipated condition differed from those in the preplanned condition, and (2) sprint time with change of direction in the unanticipated condition was associated with leg extension power, but not with selective reaction time.

DESCENTE SPORTS SCIENCE Vol.34/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE