Effects of Flywheel Resistance Training on Sprinting and Change of Direction Performance in Elite Adolescent Football Players

Background: Numerous studies have reported accelerated muscle hypertrophy, strength, and power adaptations following chronic bouts of isoinertial Flywheel Resistance Training (FRT). These factors contribute to Change of Direction (CoD) speed and sprinting performance, which are key determinants of performance in football. Progression through to the senior elite level dictates the necessity to develop these qualities in adolescent populations. Aim: To determine whether ≥ 4 weeks' FRT enhances CoD and sprinting performance in adolescent football players versus traditional strength training. Methods: PubMed and SPORT Discus electronic databases were used in February 2021. The search strategy identified randomised controlled trials, randomised crossover trials, and controlled non-randomised, full-text peer-reviewed publications written in English. Study quality was assessed by conducting a modified Downs and Black checklist. Results: A total of 21 studies were found, and following the removal of duplicates and studies based on title and abstract screening, eight studies remained. Following eligibility screening, three studies were included in the systematic review. A total of 67 subjects participated in the included studies. FRT training provides evidence that sprint performance over distances from 10 to 40-m can be improved (effect sizes: 10m = -1.8 ± 2.4%); 20m (ES = 0.37); 30m (ES = -1.5 ± 1.1%); 40m (ES = -1.1 ± 1.0%); and flying 10m (ES = 0.77) and that FRT induces significant improvements in CoD (different distances and for dominant and non-dominant limbs) compared to a control condition where subjects continued with their football training. Conclusion: Although the included studies suggest that 10-27 weeks' FRT may improve CoD and sprint performance in adolescent football players, paucity in the available literature makes such a conclusion premature. Further research in the area would ideally account for the device, moment of inertia, and transfer mechanism