Soccer requires a variety of physical qualities that athletes must develop in order to be competitive and successful at the highest levels. These qualities include but are not limited to: strength, power, acceleration, reactive ability, agility, and endurance. Short sprints over 20 meters are often made to contend for a free ball, to intercept a pass or to make a break for the goal. Therefore, a high rate of acceleration can be devastating to the opponent and be the difference between winning and losing important matches.
A plethora of research demonstrating the association between lower body maximal strength and short sprint speed has amassed, leaving little doubt that getting stronger will contribute to greater acceleration. Despite the overwhelming evidence, soccer culture is still somewhat resistant to strength training. Some fear that it will make them too bulky, less mobile and end up slowing them down. Many strength and conditioning coaches are faced with the challenge of trying to convince coaching staff and players that not only will strength training improve their performance, but also reduce their risk of injury.
A new study published ahead of print in the Journal of Strength and Conditioning Research provides some strong evidence for strength training in soccer players to improve performance. The researchers tested 1RM back squat and 20 m sprinting speed (with 5 and 10 m splits) before and after a 6-week in-season strength training program in 17 professional male soccer players. The in-season program consisted of 2 sessions per week split into a high volume and low volume session based on the competition schedule. Low volume sessions consisted of 3 sets of 3 reps with 85-90% of 1RM while high volume sessions consisted of 4 sets of 5 reps with 85-90% of 1RM. Romanian deadlifts and Nordic curls were also included in the program.
The results showed that maximal squat strength significantly improved by over 50 lbs. Sprint times for 5, 10 and 20 meters were all significantly improved with effects sizes ranging from small to moderate. Changes in 1RM back squat significantly correlated with 5, 10 and 20 m sprint times with r values of 0.62, 0.78 and 0.60, respectively. Therefore, not only did the in-season program make the athletes stronger, this newfound strength carried over to on-field sprint performance, making the athletes faster. These results are not surprising. Increased maximal lower body strength contributes to the high ground reaction forces and impulse required in maximal sprinting. Soccer coaches would therefore be wise to include in-season strength training with their teams if they value short-distance sprinting speed.
Style, WJ., et al. Effects of strength training on squat and sprint performance in soccer players. Journal of Strength and Conditioning Research, Ahead of print.