It’s easy for coaches without a background in strength and conditioning to overlook the importance of in-season strength training. Practice time with their athletes is limited and prioritizing technical and tactical work over strength training is quite tempting. However, it’s important for coaches to remember that physical qualities such as maximal strength, underpin performance of various movement demands that players are exposed to in practice and during competition. Racing for the ball, changing direction to deke an opponent, jumping to fight for a high ball, etc. are all performance variables that are impacted by strength levels. Therefore, budgeting a little bit of time once or twice per week for strength work can be very beneficial.
A new study published ahead of print in the Journal of Strength and Conditioning Research compared the performance effects of in-season strength training versus normal practicing without strength training among a team of junior soccer players. Nine-teen players were randomly allocated to the experimental group and twelve players served as controls. Twice per week throughout an 8-week in-season period, the experimental group performed barbell half-squats with loads ranging from 70 – 90% of 1 repetition maximum. The strength workouts were approximately 30 minutes in duration. The control group performed normal soccer training while the experimental group lifted. Before and after the 8-week training period, all subjects were tested in numerous speed, agility and fitness tests. Changes in performance after the intervention were compared between groups.
The results showed that the experimental group showed significant improvements in 10, 20, 30 and 40 m sprinting speed while no significant improvements were observed for the control group. Similarly, change of direction tests were significantly improved in the experimental group with no significant improvement observed in the control group. Measures of lower body strength (e.g., 1RM squat), explosiveness (e.g., countermovement-jump) and leg muscle thickness significantly improved only in the experimental group. Neither group significantly improved in the repeated sprint ability test. These results highlight the importance of in-season strength training for inducing improvements in numerous performance variables related to strength, power, speed and explosiveness. Therefore, coaches should resist temptation to forego strength training during the season. Including heavy back squatting alone appears to be effective and time-efficient.
Hammami, M., et al. (2017) Effects of lower-limb strength training on agility, repeated sprinting with changes of direction, leg peak power, and neuromuscular adaptations of soccer players. Journal of Strength and Conditioning Research, Ahead of print.