Purpose To establish the load-velocity relationships during backward sled pulling and compare this to forward sled pulling and determine the reliability of running speeds and associated load-velocity regression slopes...Purpose To establish the load-velocity relationships during backward sled pulling and compare this to forward sled pulling and determine the reliability of running speeds and associated load-velocity regression slopes in youth athletes.Methods Twenty-one boys(age,13.6±0.28 years old;height,1.72±0.09 m;mass,66.1±8.2 kg;maturity,0.57±0.72 years from peak height velocity)performed backward and forward resisted running on three occasions.Load-velocity relationships were established using an un-resisted sprint and resisted sled pull with loads of 25%-81%body mass(BM)in both directions,and the reliability of sprint times at each load and the load-velocity regression slopes were examined.Results The load-velocity data was reliable across multiple testing occasions for backward(CV≤7.2%;ICC 0.67-0.91)and forward sled pulling(CV≤7.2%;ICC 0.66-0.91).From the regression lines(R2≥0.99;P≤0.01),it was observed that averaged loads across the sample of 31%,46% and 61% BM resulted in 27%,38% and 48% decrease in velocity during backward sled pulling and 23%,33% and 43% during forward sled pulling.Increasing backward and forward loads by∼13% and~15% BM respectively,reliably resulted in∼10% decreases in velocity.Conclusion If contractile overload of the lower limbs is a focus of training then practitioners should preferentially use back-ward sled pulling.Both backward and forward sled pulling can be used in a similar manner regarding loading,though back-ward velocity is more sensitive to load and therefore overloading backward motion should be prescribed with this in mind.展开更多
文摘Purpose To establish the load-velocity relationships during backward sled pulling and compare this to forward sled pulling and determine the reliability of running speeds and associated load-velocity regression slopes in youth athletes.Methods Twenty-one boys(age,13.6±0.28 years old;height,1.72±0.09 m;mass,66.1±8.2 kg;maturity,0.57±0.72 years from peak height velocity)performed backward and forward resisted running on three occasions.Load-velocity relationships were established using an un-resisted sprint and resisted sled pull with loads of 25%-81%body mass(BM)in both directions,and the reliability of sprint times at each load and the load-velocity regression slopes were examined.Results The load-velocity data was reliable across multiple testing occasions for backward(CV≤7.2%;ICC 0.67-0.91)and forward sled pulling(CV≤7.2%;ICC 0.66-0.91).From the regression lines(R2≥0.99;P≤0.01),it was observed that averaged loads across the sample of 31%,46% and 61% BM resulted in 27%,38% and 48% decrease in velocity during backward sled pulling and 23%,33% and 43% during forward sled pulling.Increasing backward and forward loads by∼13% and~15% BM respectively,reliably resulted in∼10% decreases in velocity.Conclusion If contractile overload of the lower limbs is a focus of training then practitioners should preferentially use back-ward sled pulling.Both backward and forward sled pulling can be used in a similar manner regarding loading,though back-ward velocity is more sensitive to load and therefore overloading backward motion should be prescribed with this in mind.
