Elastic Band Training Across Competitive Levels in Female Soccer: A Randomized Controlled Trial With Follow-up

Background: Resistance training is a fundamental component of performance in female soccer; however, conventional weight training may be impractical for teams with limited facilities and equipment. Elastic band resistance training (EBT) offers a practical alternative. Hypothesis: A 9-week EBT program will enhance lower-limb strength, vertical jump, and change-of-direction (COD) speed in trained and highly trained female soccer players. Study Design: Randomized controlled trial. Level of Evidence: Level 2. Methods: A total of 74 players were divided into Under-15 (U15; n = 25), Under-19 (U19; n = 25), and Senior (n = 24) groups. Each age group was assigned randomly to an experimental or control group. The intervention was integrated into the in-season regimen, performed twice weekly before training sessions, over 9 weeks. The training protocol included 6 resistance exercises split across 2 weekly circuit-based sessions. Isometric knee extension (KE) and knee flexion (KF) strength, countermovement jump (CMJ) height and power, and T-test performance were evaluated pre- and postintervention and after a 3-week detraining period. Results: Difference-in-differences ordinary least squares regression analysis revealed improvements in U19 KE strength of the dominant and nondominant leg (coefficient = 132.90 N; P = 0.03 and 131.59 N; P = 0.05, respectively). KF strength improved marginally in U15 and Senior groups. Senior players also showed a nonsignificant positive trend towards CMJ power (coefficient = 581.08 W; P = 0.09), with no relevant changes in CMJ height or T-test. After detraining, strength gains declined across all groups, while CMJ and T-test metrics remained stable. Conclusion: EBT enhances knee strength effectively, particularly in older age groups, but its influence on vertical jump and COD speed is limited. The reversal of strength gains after short-term detraining highlights the importance of consistent training for sustained athletic development. Clinical Relevance: EBT is a practical, low-cost method to improve lower-limb muscle strength in female soccer players and can be integrated easily into in-season training when traditional equipment is unavailable.