Since most team sports consist of intermittent, short distance sprints with rapid changes of direction, the ability to accelerate tends to be more important than maximum velocity speed. It is quite rare that an athlete reaches maximum velocity during a competition without any interruption caused by a deceleration or direction change. Therefore, our efforts in training should focus on enhancing the acceleration phase of sprinting with our athletes. Ground contact time is longer during acceleration as the athlete must apply high levels of force into the ground to propel himself forward. Therefore, lower body strength levels are a big predictor of acceleration ability. This includes both absolute and relative lower body strength. Hypothetically, an increase in squat strength should then lead to increases in acceleration ability.
In a recent study by Comfort et al. (2012), 19 male professional rugby league players were tested in 1RM squat strength and 5, 10 and 20 meter sprint times before and after an eight week off-season training program. The mean pre-training values for absolute squat strength and relative strength (1RM/body weight) were 170.6 ± 21.4kg and 1.78 ± 0.27kg respectively. Pre-training 5, 10 and 20m sprint times were 1.05 ±0.06s, 1.78 ± 0.07s, and 3.03 ± 0.09s respectively. Following the eight week program, absolute and relative strength levels improved significantly to 200.8 ± 19kg and 2.05 ± 0.21kg respectively. Five, 10 and 20m sprint times also improved (0.97 ± 0.05s, 1.65 ± 0.08s and 2.85 ± 0.11s respectively). The training program resulted in a 17.7% increase in maximal squat strength as well as a 7.6% decrease in 5m sprint time, a 7.3% decrease in 10m sprint time and a 5.9% decrease in 20m sprint time.
Unfortunately, the results of this particular study should be interpreted with caution as the training program involved much more than just strength training. As these were elite level athletes, limiting them to only strength work would not sufficiently prepare them for the upcoming season. Therefore, the increase in 1RM squat strength was only associated with the improvement in acceleration and was not necessarily causative as other factors were at play (plyometrics, power training, etc.). However, the researchers believe that the increase in strength contributed to a greater level of force production in the early acceleration phase that could explain the larger improvement in speed at the 5 and 10m marks. Given the strong association shown in this investigation, directing efforts to improving maximal squat strength in our athletes may yield improvements in acceleration.
Comfort, P., Haigh, A., & Matthews, M. J. (2012). Are changes in maximal squat strength during preseason training reflected in changes in sprint performance in rugby league players?. The Journal of Strength & Conditioning Research, 26(3), 772-776.