Relationship between sprint start variables and muscle function of lower extremities for rugby players in a Japan Top League club

Abstract

The purpose of this study was to clarify relationship between sprint start variables which seemed to be affecting explosive acceleration ability and the muscle function of lower extremities. 25 male rugby players of a team which belonged to the Japan top league cub performed 5m sprint start, barbell squat, squat jump and rebound jump test. Average step velocity from the 1st to 4th step (V1-4Step) which play important role in explosive acceleration ability in sprint start was analyzed. Step length, flight time, and contact time showed significant correlations with V1-4Step, however, there was no significant relationship between V1-4Step and step frequency. V1-4Step showed significant correlations with body mass ratio of jump squat power for 20 kg, 30%1RM, 60%1RM, 80%1RM, respectively, and rebound jump index. Comparing the difference of sprint variables and the muscle functions of the lower extremities between the higher ranked group and lower rank group divided by the V1-4Step, higher ranked group showed significantly lager step length, flight time, body mass ratio of the power for 20kg and 60%1RM, and rebound jump index. There were insignificant but very large difference in the contact time, and the body mass ratio of the power for the 30% and 80%1RM, higher ranked group showed shorter contact time and higher body mass ratio of the power. From these results, to achieve shorter contact time while increasing a step length appeared to be important to improve V1-4Step. In addition, it seemed to be necessary to increase body mass ratio of the power for the loads ranged from light to heavy, and improve reactive leg strength performed in stretch shortening cycle muscle activities.