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.
Jarvis, P. et al. The acute effects of heavy sled towing on subsequent sprint acceleration performance. Journal of Trainology. 2017;6:18-25.