Sequencing effects of balance and change of direction training on physical fitness in young male and highly trained soccer players.

The capacity to quickly change directions is a critical success factor in soccer. Accordingly, change-of-direction training (CODT) should be part of soccer training. Whether there is a sequencing effect of CODT with other training modalities is currently unresolved. Thus, the study objective was to examine the sequencing effects of balance training (BT) and CODT on selected measures of physical fitness and soccer-specific performance in highly-trained young soccer players. Thirty-seven highly-trained male pubertal soccer players aged 12-13 years (Tier 3) exercised for eight weeks with two weekly CODT (forward, backward and lateral drills) or BT (e.g., bi- and unilateral exercises on unstable surfaces) sessions included in regular soccer training sessions. While experimental group 1 (n = 18) performed four weeks of BT followed by four weeks of CODT, group 2 (n = 19) followed the opposite sequencing scheme (CODT before BT). BT or CODT lasted 20 min per session and replaced parts of the soccer-specific training, including technical, tactical drills and small-sided games. Pre and post-training, tests were conducted for the assessment of static, dynamic balance (i.e., center of pressure surface area, velocity on firm, foam surfaces), linear sprint speed (i.e., 5-m, 10-m, 30-m) and change-of-direction (COD) ability (i.e., 15-m COD ability test) with and without the ball. Vertical and horizontal jump performances were tested using the countermovement and the standing long jump tests. Once statistical assumptions were met, a two-way repeated-measures analysis of variance (ANOVA) was computed with the factors 'group' (BT before CODT vs. CODT before BT) as the between-subject factor and 'time' (pre-test vs. post-test) as the within-subject factor. Findings showed significant group-by-time interactions for all proxies of static (d = 0.45-1.12; all p < 0.01) and dynamic balance (d = 0.40 - 0.27; all p < 0.03), COD with (d = 0.64; p < 0.02) and without the ball (d = 0.24; p < 0.04), horizontal and vertical jump performances (d = 1.89-2.94; all p < 0.001) and linear sprints (d = 0.29-0.73; all p < 0.04). Post-hoc tests indicated significant pre-post changes for all tested variables for the group that performed BT before CODT (d = 0.28-1.97; all p < 0.05) and to a lesser extent for the opposite sequencing scheme (d = 0.10-0.28; all p < 0.05). A mesocycle commencing with BT prior to CODT appears to have a preconditioning effect, resulting in better outcomes in balance, speed, and jump performances in highly-trained young soccer players. Strength and conditioning professionals working with young male soccer players may apply a block of BT before CODT to enhance their players' performance.