Strength training in the development of power in soccer players of the inferior divisions of Deportivo Independiente Medellín (DIM), in Colombia

Abstract

Theoretically, high levels of strength correlate with improvement in manifestations of immediate muscular power, which is a decisive variable of performance in modern soccer.

Purpose: to de- urpose: termine in soccer players if strength training at a high percentage (85%) of 1-RM, looking for increase in maximum strength, is more effective in improving immediate muscular power than a similar training but at 75% of 1-RM.

Methodology: 60 soccer players belonging to the inferior divisions of DIM were randomly assigned to either one of two groups of 30 players each, and performed the following strength training protocols: the experimental group carried out an individual bilateral force training for knee extensors and flexors that consisted of 3 series of 5 repetitions each, at 85% of 1-RM, with 5 minutes of rest between series, twice a week during 12 weeks. The control group trained the same muscular groups, 3 series of 8 repetitions each, at 75% of 1-RM, also with 5 minutes of rest between series, twice a week during 12 weeks. At the onset, and at 6 and 12 weeks measurements were made of maximum strength (1-RM) of knee extensors and flexors and of immediate muscular power: speed in 20 m, Squat Jump and Countermovement Jump.

Results: although the 60 players completed the training, data were analyzed for only 29 in the experimental group and 27 in the control one; of the remaining 4 participants, 2 left the team and 2 suffered injuries unrelated with the training. No significant differences were found between the two groups, in any of the variables, in any of the 3 measurements. Most of the variables -strength of the right knee extensors, strength of the left knee extensors, strength of the right knee flexors, strength of the left knee flexors, Squat Jump, Countermovement Jump – had statistically significant increases (p < 0.05) in each group both at 6 weeks and between weeks 6 and 12, the only exception being the speed in 20 m that presented significant increase only at six weeks. For both groups, the r Pearson´s correlation between maximum strength of right knee extensors, SJ and CMJ ranged from moderate to high and were statistically significant (p < 0.05) at the beginning of the study as well as at 6 and 12 weeks of the maximum strength training; correlation with the speed in 20 m was found only at the beginning of the work.

Conclusions: maximum strength training at intensities of 75 and 85% of 1-M produces significant improvement in immediate muscular power.