Effects of Contrast Strength vs. Plyometric Training on Lower Limb Explosive Performance, Ability to Change Direction and Neuromuscular Adaptation in Soccer Players.

The aim was to compare the effects of two differing 8-week in-season strength training programs (contrast strength training [CST] vs. plyometric training [PT]) on selected performance tests (5 and 40m sprints, S 4 X 5 m change of direction test, squat (SJ) and countermovement (CMJ) jumps , leg peak power on a cycle ergometer force-velocity test, 1-repetition maximal (1-RM) half squat, and electromyographic [EMG] activity of the vastus lateralis, vastus medialis and rectus femoris muscles during vertical jump tests). Forty male soccer players (age = 15.8 ± 0.4 years; body mass = 58.8 ± 6.3 kg; body height = 1.74 ± 0.06 m; body fat = 10.5 ± 1.9 %) were divided between a contrast strength (CSG, n = 14), plyometric (PG, n = 14) and control groups (CG, n = 12). Both training programs enhanced sprint performance (p<0.001 in 5m; p≤0.05 in 40m) and change of direction test scores (p<0.001) relative to controls. PG and CSG increased SJ height relative to the CG, with a slightly greater response in CSG compared to PG (p≤0.05). The majority of CMJ scores increased significantly in both CSG and PG relative to the CG, with no inter-group differences in training response. The majority of force-velocity scores increased significantly in the CSG relative to PG and CG. The EMG parameters also increased in the CSG relative to both PG and CG. In summary, most measures of athletic performance in male soccer players were enhanced after CST and PT. However, the improvement of physical performance was better with eight weeks of CST than with PT. Thus, coaches should be encouraged to include CST as an element of in-season conditioning.