Effect of strength-to-weight ratio on the time taken to perform a sled-towing exercise

María Asunción Martínez-Valencia, Nicholas P. Linthorne, José M. González-Ravé, Pedro E. Alcaraz, Fernando Navarro Valdivielso

Abstract

Sled-towing exercisesare effective at developing sprint acceleration in sports. In a sled-towingexercise the time taken by an athlete to tow the sled over a given distance isaffected by the weight of the sled, the frictional properties of the runningsurface, and the physiological capacities of the athlete. To accurately set thetraining intensity for an athlete, the coach needs a detailed understanding ofthe relationships between these factors. Our study investigated therelationship between the athlete’s strength-to-weight ratioand the rate of increase in sled-towing time with increasing sled weight. Twenty-two male athletes performed aone-repetition maximum (1RM) half-squat and sled-towing exercises over 20 mwith sleds of various weights. The strength of the correlation between 1RM half-squat performance (normalized to bodyweight)and the rate of increase in sled-towing time with increasing sled weight was interpreted using the Pearson product-moment correlationcoefficient. As expected, we found substantialinter-athlete differences in the rate of increase in time with increasing sledweight, with a coefficient of variation of about 21% and 17% for sled-towingtimes over 10 and 20 m, respectively. However, the rate of increase in sled-towing time showed nocorrelation with normalized 1RM half-squat performance (r = –0.11, 90% confidence interval = –0.45 to 0.26; and r = –0.02, 90% confidence interval =–0.38 to 0.34, for sled-towing times over 10 and 20 m, respectively). Theseresults indicate thatinter-athlete differences in the rate of increase in sled-towingtime with increasing sled weight are not likely to be due to differences instrength-to-weight ratio. Instead,we recommend the weight of the sled be scaled according to the athlete’spower-to-weight ratio.

Keywords

Athletics; Biomechanics; Kinematics; Sprinting

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DOI: https://doi.org/10.14198/jhse.2017.121.16