Interrelationships between different loads in resisted sprints, half‐squat 1 RM and kinematic variables in trained athletes

Abstract

Resisted sprint running is a common training method for improving sprint-specific strength. It is well-known that an athlete's time to complete a sled-towing sprint increases linearly with increasing sled load. However, to our knowledge, the relationship between the maximum load in sled-towing sprint and the sprint time is unknown, The main purpose of this research was to analyze the relationship between the maximum load in sled-towing sprint, half-squat maximal dynamic strength and the velocity in the acceleration phase in 20-m sprint. A second aim was to compare sprint performance when athletes ran under different conditions: un-resisted and towing sleds. Twenty-one participants (17.86 ± 2.27 years; 1.77 ± 0.06 m and 69.24 ± 7.20 kg) completed a one repetition maximum test (1 RM) from a half-squat position (159.68 ± 22.61 kg) and a series of sled-towing sprints with loads of 0, 5, 10, 15, 20, 25, 30% body mass (Bm) and the maximum resisted sprint load. No significant correlation (P<0.05) was found between half-squat 1 RM and the sprint time in different loaded conditions. Conversely, significant correlations (P<0.05) were found between maximum load in resisted sprint and sprint time (20-m sprint time, r=-0.71; 5% Bm, r=-0.73; 10% Bm, r=-0.53; 15% Bm, r=-0.55; 20% Bm, r=-0.65; 25% Bm, r=-0.44; 30% Bm, r=-0.63; MaxLoad, r= 0.93). The sprinting velocity significantly decreased by 4-22% with all load increases. Stride length (SL) also decreased (17%) significantly across all resisted conditions. In addition, there were significant differences in stride frequency (SF) with loads over 15% Bm. It could be concluded that the knowledge of the individual maximal load in resisted sprint and the effects on the sprinting kinematic with different loads, could be interesting to determinate the optimal load to improve the acceleration phase at sprint running.

Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the Acceleration Phase

“…The results showed that an increase in loads led to a decrease in sprint performance over 20 and 30 m when athletes ran under different conditions (10%, 15%, and 20% Bm). Similar results may be found in previous studies ( Alcaraz et al, 2009 ; Cronin et al, 2008 ; Keogh et al, 2010 ; Letzelter et al, 2005 ; Linthorne, 2013 ; Lockie et al, 2003 ; Martínez-Valencia et al, 2014 ; Maulder et al, 2008 ; Murray et al, 2005 ). Lockie et al (2003) found that loads of 12% and 32% Bm decreased velocity during 15 m acceleration to 91% and 76%, respectively.…”

“…As a result, Murray et al (2005) suggested that one test would produce valid data. Previous studies that had analyzed the effect of sled towing on sprint performance also recorded one sprint for different load conditions ( Cronin et al, 2008 ; Martínez-Valencia et al, 2013 ; Martínez-Valencia et al, 2014 ). As a result, this procedure was adopted in the current study.…”

“…Otherwise, several studies had shown that resisted sprint training had minimal impact on lower-body kinematics during the acceleration ( Clark et al, 2010 ; Lockie et al, 2013 ; Spinks et al, 2007 ) and maximum velocity ( Alcaraz et al, 2014 ) phases. As can be seen, many studies set the load in sled-towing exercise to a percentage of the athlete’s body mass ( Alcaraz et al, 2009 ; Cronin et al, 2008 ; Linthorne and Cooper, 2013; Lockie et al, 2003 ; Martínez-Valencia et al, 2014 ; Maulder et al, 2008 ; Murray et al, 2005 ), based on the fact that larger athletes tend to generate greater muscular power output ( Martínez-Valencia et al, 2013 ). However, only two studies ( Cottle et al, 2014 ; Kawamori et al, 2014b ) have been found that analyzed the acute effects of the sled-towing exercise on ground reaction force, but the results were not conclusive.…”

Complex network models reveal correlations among network metrics, exercise intensity and role of body changes in the fatigue process

“…All them keep the location in the treadmill and the position of the belt (between waist and hip). This allowed us to reproduce in the laboratory conditions similar to field tests, as in prior studies 23 24 25 .…”

Relationships between Resisted Sprint Performance and Different Strength and Power Measures in Rugby Players

“…Regarding RST loads, the present findings demonstrated that JHs in SJ, but not CMJ, were moderately correlated to L10% and L30%, but not to L50%, and this association decreased as a function of load increment. Previous research [36] reported that the increase in loads involves a decrease in sprint performance over 20 m when athletes sprinted under different conditions (unresisted and towing sleds with loads between 5% and 30% BM). The present findings suggest that, when sprinting with heavier loads, the variables that correlate with performance are different than when sprinting under unloaded conditions.…”