Speed can be a determining factor in any team-sport competition. This is why many coaches dedicate considerable time and effort into improving speed. Resisted sprint-training is a traditional means of speed development in athletes. One of the most effective and popular methods of implementing resisted sprint-training is via sled-towing. However, considerable debate surrounds optimal training strategies for this practice. For example, whether sled loads should be light (e.g., <10% of athletes body mass) or heavy remains to be determined. In addition, when using sled towing as a means of inducing post-activation potentiation to enhance subsequent sprint efforts, the optimal rest-time between towing and free-sprinting is unclear.
A new study published in the latest issue of the Journal of Trainology evaluated the acute effects of heavy sled towing on subsequent sprint acceleration performance. A sample of eight collegiate male athletes performed three different sprint protocols on different days, separated by at least 72 hours in randomized order. Protocol 1 consisted of 1 set of sled-towing over 15 m with 50% of body mass; protocol 2 consisted of 2 sets of sled-towing over 15 m with 50% of body mass and; protocol 3 consisted of 3 sets of sled-towing over 15 m with 50% of body mass. Inter-set rest periods were 90 seconds. Four minutes prior to each protocol, an unload 15 m sprint was evaluated via electronic timing gates to serve as baseline. Following each protocol, 15 m sprint time was tested at 4, 8 and 12 minutes post-sled-towing.
The results of this study showed that protocol 3 (3 sets of sled-towing with 50% of body mass) after 8 minutes of rest produced significantly faster 15 m sprint times compared to baseline sprint-speed (average improvement of 0.07, p <0.05, effect size = small). All individual subjects ran their fastest 15 m time following 8 or 12 minutes of rest. The authors conclude that performing maximal effort sled-towing with 50% of body mass for 3 sets transiently enhances sprinting speed when at least 8 minutes of rest are provided following the sled-towing protocol. Thus, coaches can implement heavy sled-towing to induce post-activation potentiation, but must be mindful of allowing adequate rest before unloaded sprinting to derive performance enhancing effects.
Reference:
Jarvis, P. et al. The acute effects of heavy sled towing on subsequent sprint acceleration performance. Journal of Trainology. 2017;6:18-25.
