The Effect of a Heavy Resisted Sled-Pull Mesocycle on Sprint Performance in Junior Australian Football Players

Abstract

Edwards, T, Piggott, B, Banyard, HG, Haff, GG, and Joyce, C. The effect of a heavy resisted sled-pull mesocycle on sprint performance in junior Australian football players. J Strength Cond Res 37(2): 388–393, 2023—This study assessed the effect of heavy resisted sled-pull training on sprint times and force, velocity, and power characteristics in junior Australian football players. Twenty-six athletes completed a 6-week resisted sled-pull training intervention which included 10 training sessions and 1-week taper. Instantaneous velocity during 2 maximal 30 m sprints was recorded 1 week before and 1 week after the intervention with a radar gun. Velocity-time data were used to derive sprint performance and force, velocity, and power characteristics. A paired t-test assessed the within-group differences between preintervention and postintervention testing. Statistical significance was accepted at p ≤ 0.05. Hedges' g effect sizes (ESs) were used to determine the magnitude of change in dependent variables. Maximum velocity (ES = 1.33) and sprint times at all distances (ES range 0.80–1.41) significantly improved after heavy resisted sled-pull training. This was reflected in sprint force, velocity, and power characteristics with significant improvements in relative theoretical force (ES = 0.63), theoretical velocity (ES = 0.99), relative maximum power (ES = 1.04), and ratio of horizontal to vertical force (ES = 0.99). Despite the multifactorial nature of training and competing physical demands associated with preseason training, these findings imply that a short, resisted sled-pull training mesocycle may improve sprint performance and underlying force, velocity, and power characteristics in junior athletes.

Hip Torque Is a Mechanistic Link Between Sprint Acceleration and Maximum Velocity Performance: A Theoretical Perspective

“…Furthermore, despite the different sprint performances expected from the representative athletes as illustrated by the velocity-time curves in Figure 1C , the acceleration-velocity curves of the representative data in Figure 1D demonstrate the general proportionality of a 0 and v 0 with a range of τ values slightly greater than one-second ( Table 1 ). Therefore, this framework presents a macro-level explanation for why group mean τ and S fv values are usually around one (τ ≈ 1 s or S fv ≈−1 s −1 ) agreeing with experimentally determined values (Healy et al, 2019 ; Morin et al, 2019 ), or values calculated from previously published maximum velocity and maximum force data (Cross et al, 2015 ; Rabita et al, 2015 ; Slawinski et al, 2017a ; Haugen et al, 2019 ; Watkins et al, 2021 ; Edwards et al, 2022 ).…”

“…Values for a 0 or normalized F 0 (N/kg) are similar to those from several recent experimental investigations (Cross et al, 2015;Rabita et al, 2015;Slawinski et al, 2017a;Haugen et al, 2019;Morin et al, 2019Morin et al, , 2021Watkins et al, 2021). Values for τ are slightly greater than onesecond, agreeing with experimentally determined values (Healy et al, 2019;Morin et al, 2019), or values calculated from previously published maximum velocity and maximum force data (Cross et al, 2015;Rabita et al, 2015;Slawinski et al, 2017a;Haugen et al, 2019;Watkins et al, 2021;Edwards et al, 2022). Variables: h b = body height, m b = body mass, L leg = leg length, tc = ground-contact time at maximum velocity, θt = total thigh range of motion at maximum velocity, fstr = stride frequency at maximum velocity, v 0 = maximum velocity limit, a 0 = maximum sprint acceleration limit equivalent to F 0 normalized to body mass (N/kg), and τ = time constant.…”

“…Values for a 0 or normalized F 0 (N/kg) are similar to those from several recent experimental investigations (Cross et al, 2015 ; Rabita et al, 2015 ; Slawinski et al, 2017a ; Haugen et al, 2019 ; Morin et al, 2019 , 2021 ; Watkins et al, 2021 ). Values for τ are slightly greater than one-second, agreeing with experimentally determined values (Healy et al, 2019 ; Morin et al, 2019 ), or values calculated from previously published maximum velocity and maximum force data (Cross et al, 2015 ; Rabita et al, 2015 ; Slawinski et al, 2017a ; Haugen et al, 2019 ; Watkins et al, 2021 ; Edwards et al, 2022 ).…”

“…Mean values for τ and S fv , either directly reported or calculated from published maximum velocity and Abbreviations: a 0 , maximum propulsive acceleration limit (m/s 2 ); BMI, body mass index (kg/m 2 ); COM, center of mass; F 0 , maximum propulsive force limit (N); f str , stride frequency (one-half the step frequency) (strides/s or Hz); h b , body height (m); I com , moment of inertia of the COM (kg•m 2 ); I leg , moment of inertia of the extended leg (kg•m 2 ); L c , ground-contact length (m); L leg , leg length (m); m b , body mass (kg); m leg , leg mass (kg); S fv , slope of acceleration-velocity curve (s −1 ); t, time (s); t c , ground-contact time (s); v 0 , maximum velocity limit (m/s); α com , maximum angular acceleration of COM (rad/s 2 ); α leg , maximum angular acceleration of extended leg (rad/s 2 ); α max , maximum angular acceleration of thigh (rad/s 2 ); θ t , total thigh range of motion (rad); ρ, radius of gyration from the proximal end (m); τ , time constant of acceleration-velocity curve (s). maximum force data, consistently have a magnitude of around one (τ ≈ 1 s or S fv ≈−1 s −1 ) even for athletes from a variety of sports with vastly different sprinting abilities (Cross et al, 2015;Rabita et al, 2015;Slawinski et al, 2017a;Jiménez-Reyes et al, 2018;Haugen et al, 2019;Healy et al, 2019;Morin et al, 2019;Watkins et al, 2021;Edwards et al, 2022). This indicates that the acceleration and velocity performance limits are related and generally proportional.…”

“…As shown in Figure 1B , since maximum horizontal acceleration (m/s 2 ) is equivalent to the maximum horizontal force relative to body mass (N/kg), the resultant acceleration-velocity curve can be defined by the limits a 0 and v 0 with a negative linear slope ( S fv = - a 0 / v 0 = −1/τ). Mean values for τ and S fv , either directly reported or calculated from published maximum velocity and maximum force data, consistently have a magnitude of around one (τ ≈ 1 s or S fv ≈−1 s −1 ) even for athletes from a variety of sports with vastly different sprinting abilities (Cross et al, 2015 ; Rabita et al, 2015 ; Slawinski et al, 2017a ; Jiménez-Reyes et al, 2018 ; Haugen et al, 2019 ; Healy et al, 2019 ; Morin et al, 2019 ; Watkins et al, 2021 ; Edwards et al, 2022 ). This indicates that the acceleration and velocity performance limits are related and generally proportional.…”