The Trainability of Adolescent Soccer Players to Brief Periodized Complex Training

Purpose: To investigate the effect of a complex, short-term strength/power training protocol on performance and body composition of elite early adolescent soccer players. Methods: Twenty-two players (14-15 y) were randomly assigned to (1) an experimental group (N = 12; participated in a 5-wk training protocol with traditional multijoint power resistance exercises, Olympic-style lifts, plyometric drills, and speed work; 4 times per week) or (2) a control group (N = 10). Strength and power performance (jumping, speed, change of direction, repeated sprint ability, endurance, isokinetic strength of knee flexors and extensors, maximal strength in various lifts, and speed-endurance) were evaluated pretraining and posttraining. Results: Cessation of training for 5 weeks in the control group induced a marked performance deterioration (similar to 5%-20%). Training not only prevented strength performance deterioration but also increased it (similar to 2%-30%). Endurance and repeated sprint ability declined to a smaller extent in experimental group compared with control group (15% vs 7.5%). Isometric strength and body composition remained unaltered in both groups. Conclusions: Results demonstrate that (1) young players exhibit a high level of trainability of their strength/power performance (but not endurance) in response to a short-term complex training protocol during early adolescence, (2) Olympic-style lifts are characterized by increased safety in this age group and appear to be highly effective, (3) lifts incorporating a hip thrust result in increased strength of both knee extensors and flexors, (4) cessation of training for only 5 weeks results in marked deterioration of strength/power and endurance performance, and (5) improvement of strength/power performance may be related to neural-based adaptation as body composition remained unaffected.