Effect of training load on lower limb power and jumping ability of professional soccer players

Abstract

Research objective: The main research objective is to analyze the effects of training load on the lower limb power and jumping ability used in the maximum strength phase I during the preparatory period after the fall round league games among professional soccer players. Materials and Methods: The research material was a selected group of soccer players (n = 56) of the first Polish league, representing a similar sports level with a minimum of 4 years of training experience in the league and in the age range of 22 to 28 years. The study is focused on comparing two strength training programs which have been based on varying the intensity of training (% 1 RM). The first group performed training with an external load of 50-60% of 1RM (SG1), while the second group performed training with a load of 70-80% of 1RM (SG2). The training plan ran over 4 weeks (2 sessions per week; 4-number of series; 5-number of repetitions; 3-minute interval time between series; 2-minute interval time between exercise), with pre- and post-tests which included: anthropometry, 1RM, peak power output with 50% (unilateral), 60% (bilateral) (SG1) and 70% (unilateral), 80% 1RM (bilateral) (SG2) in the leg press, squat, and CMJ. The use of pneumatic devices the Keiser Leg Press A420 and Keiser Air Squat A300 (Keiser, Fresno, CA, USA) was used to measure the generated power of the lower limb muscles (leg press, squat). The dynamometric device Force Decks Dual Force Plate System (Brisbane, Queensland, Australia) was used to measure the jumping ability (CMJ). Results: Analyzing the changes in power generated during leg presses and during squats, it should be concluded that the results in both groups improved. However, the changes in the SG1 group, using an external load of 50-60% 1RM, were significantly greater. Interestingly, in the SG2 group, using an external load of 70-80% 1RM, the level of power generated by the right lower limb during the unilateral squat decreased after training. Similarly, to the jumping ability, greater changes were recorded in the SG1 group after completing the training program. The SG1 group with training using an external load of 50-60% 1RM achieved significantly better results than the SG2 group with training using an external load of 70-80% 1RM for 7 variables: bilateral leg press, unilateral leg press (right lower limb), unilateral leg press (left lower limb), bilateral squat, unilateral squat (right lower limb), power [W/kg] and the speed [m/s] of the jump. It was also possible to observe a certain increasing trend in the results in the unilateral squat (left lower limb) and countermovement jump height (CMJ), while not statistically significant. Conclusions: The method of using moderate and heavy loads can be used in the maximum strength phase I during the preparatory period after the fall round league games as an effective solution to improve the results in terms of power and jumping ability generated by soccer players. The main findings of the present study were as follows: training with an external load of 50-60% 1RM during the preparatory period after the fall round league games is more effective in improving muscle power and jumping ability (power [W/kg] and the speed [m/s] of the jump) soccer players than training with an external load of 70-80% 1RM.