24 Feb FSI Football Science Update

Introduction:

Performance improvement with resistance training is a booming area in team sports. Weight training is essential for the development of specific game skills (i.e., change of direction, sprinting, jumping). In fact, there are many studies that analyze the design that strength training should have to improve isolated skills. In this sense, the choice of unilateral or bilateral resistance training exercise is one of the great doubts in our community. Given that key phases of athletic performance such as sprinting and change of direction (COD) occur in 1 leg, unilateral resistance training (UNI) is perceived to offer greater movement specificity than bilateral exercises (BI). However, the unstable base (i.e., unilateral) may also reduce the magnitude of external load required for strength development and subsequent improvement in sports performance in trained individuals.

«Given that key phases of athletic performance such as sprinting and change of direction (COD) occur in 1 leg, unilateral resistance training (UNI) is perceived to offer greater movement specificity than bilateral exercises (BI). However, the unstable base (i.e., unilateral) may also reduce the magnitude of external load»

Purpose:

Examine the changes in sprint acceleration and COD ability as a result of resistance training using either bilateral (squat) only or unilateral (step-up) only.

Method:

49 male subjects were recruited from a state rugby union academy program and grade club competition for the 3 groups, of which 33 (mean ± SD: age = 22.4 ± 4.1 years). The study design is shown in figure 1 below.

Figure 1. Schematic representation of study design.

Results (table 6 in full text):

• BIL and UNI groups improved their trained and non-trained strength exercise with an unclear difference in adaptation of squat strength (ES = 0.34 ±55).
• Both groups improved 20-m sprint (ES: BIL = 0.38 ±49 and UNI = 0.31 ± 0.31); however, the difference between the groups was unclear (ES = 0.07 ± 0.58).
• Although both groups had meaningful improvements in COD performance, bilateral resistance training had a greater transfer to COD performance than unilateral resistance training (between-groups ES = 0.59 ± 0.64).

 

Table 6. Magnitude of within-group changes in speed and change of direction at weeks 9 and 12 compared with baseline for bilateral, unilateral, and comparison groups*†.

Take home messages:

• Both unilateral (step-up) and bilateral (squat) exercises can transfer to sprint acceleration performance.
• Non-specific resistance training exercises should be combined with conditions that simulate the competition scenarios, but especially in the COD (address the underlying neuromuscular requirements of the task).
• Non-specific exercises in resistance training should be chosen according to the demands of game movements (i.e., contraction type and overload as critical elements of exercise selection).

«Resistance training exercises should be combined with conditions that simulate the competition scenarios, but especially in the COD»