Comparative analysis of unilateral versus bilateral training effect on strength and balance of alpine skiers

Abstract

Research aim: The aim of this study was to compare two training methodologies regarding strength and balance (Unilateral vs Bilateral) in order to determine which specific training method will have the highest impact on the lower body strength and balance of alpine skiers.Methods: 23 young male and female alpine skiers with an average age 24 years old participated in the study. Subjects were randomly divided into 2 groups of training: Bilateral training (n=11) and Unilateral training (n=12). Both groups underwent a 4 weeks training program twice per week training lower strength and balance and have been tested before the training and after. First group bilateral training (BT) included 3 main lower bilateral strength exercises: squat, leg curl and leg extension with bilateral balance exercises: 1st exercise: weight shift focused on hip angulation with squat hold on flat surface of BOSU ball, 2nd walking ankle to toe on the battle rope and 3d exercise balancing on a balance board. The second group unilateral training (UT) included the same main lower strength and balance exercises but unilaterally. Balance training load was progressive each week; Same for Strength training load for week1 was at 70% of 1RM, for week 2 and 3 was at 80% of 1RM and for week 4 was at 90% of 1 RM. Results: At the end of the study, and when comparing Test 1 with Test 2, significant differences were observed in 1RM and balance tests between unilateral and bilateral training methodologies. For 1RM squat, increases were observed from 79.09 ± 23.37 Kg to 105.95 ± 28.92 Kg in the bilateral group, and from 90.75 ± 40.11 Kg to 108.5 ± 43.27 Kg in the unilateral group, with respective increases of 35.00 ± 9.00% in bilateral and 21.00 ± 9.00% in unilateral. For 1RM single leg squat, the bilateral group saw increases from 79.18 ± 14.67 Kg to 86.36 ± 15.75 Kg on the right and 78.54 ± 13.93 Kg to 85.36 ± 15.62 Kg on the left, while the unilateral group experienced more substantial improvements from 80.41 ± 18.15 Kg to 99.29 ± 22.37 Kg on the right and 80.72 ± 18.27 Kg to 99.21 ± 24.15 Kg on the left, indicating the unilateral exercises' effectiveness in enhancing single-leg strength. Moreover, the difference in performance between the left and right legs in single leg squats, which serves as a measure of lower body strength symmetry, showed significant improvements in the unilateral group only.The 1RM leg extension results further highlighted this, with bilateral training showing increases from 97.64 ± 48.27 Kg to 126.57 ± 54.65 Kg, and unilateral training from 103.13 ± 46.81 Kg to 134.75 ± 49.69 Kg. The differences between the right and the left leg performances, initially more pronounced in the unilateral group, were reduced, mirroring the trends observed in single leg squats and emphasizing unilateral training's impact on correcting asymmetries. In the BASS single leg test, the unilateral training group showed marked improvements, with an 11.00 ± 6.00% increase. This contrasted with the bilateral group's less gain of 2.00 ± 7.00% improvement. In the BOSU single leg stand, the unilateral group's hold also increased more in the unilateral group compared to the bilateral group.Conclusion: The results indicated that unilateral training was as effective as bilateral training in improving bilateral strength and balance but more effective in improving unilateral strength, balance and lower limb asymmetry for alpine skiers.