Sled-push load-velocity profiling and implications for sprint training prescription in young athletes

Abstract

Resisted sled pushing is a popular method of sprint-specific training; however, little evidence exists to support the prescription of resistive loads in young athletes. The purpose of this study was to determine the reliability and linearity of the force-velocity relationship during sled pushing, as well as the amount of between-athlete variation in the load required to cause a decrement in maximal velocity (Vdec) of 25, 50 and 75%. Ninety (n=90) high school, male athletes (age 16.9 ± 0.9 years) were recruited for the study. All participants performed one un-resisted and three sled-push sprints with increasing resistance. Maximal velocity was measured with a radar gun during each sprint and the load-velocity relationship established for each participant. A subset of 16 participants examined the reliability of sled pushing on three separate occasions. For all individual participants, the load-velocity relationship was highly linear (r > 0.96). The slope of the load-velocity relationship was found to be reliable (CV = 3.1%), with the loads that cause a decrement in velocity of 25, 50 and 75% also found to be reliable (CVs = <5%). However, there was large between-participant variation (95%CI) in the load that caused a given Vdec, with loads of 23-42% body mass (%BM) causing a Vdec of 25%, 45-85%BM causing a Vdec of 50% and 69-131%BM causing a Vdec of 75%. The Vdec method can be reliably used to prescribe sled-push loads in young athletes, but practitioners should be aware that the load required to cause a given Vdec is highly individualized.