Acute effects of sled towing on sprint time in male youth of different maturity status

The purpose of this study was to investigate the effect of 2.5, 5, 7.5, and 10% body mass load on resisted sled towing 30 meter sprint times in male youth athletes of different maturity status. A total of 35 athletes (19 prepeak-height-velocity (PHV) and 16 mid/post-PHV) sprinted three times in an unloaded and each of the loaded conditions. The pre-PHV athletes were significantly slower (∼33%; p < .05) than the more mature athletes across all loads (unloaded, 2.5, 5, 7.5, 10% body mass). Each incremental load (i.e., 2.5% body mass) was found to reduce 30 m sprint times by 3.70% (± 2.59) and 2.45% (± 1.48) for the pre- and mid/post-PHV respectively. The slopes of the pre- (y = 0.09 x + 5.71) and mid/post (y = 0.04 x + 4.38) regression equations were compared and found to be statistically different (p = .004) suggesting that athletes of different maturity status responded differentially to the same relative resisted sprint load. Ten percent body mass load resulted in a reduced sprint time of ∼15.8 and ∼9.8% for the pre- and mid/post-PHV group, respectively. These results enable predictive equations to be formulated and appropriate resisted sprint loading, based on the intended focus of a session.