Introduction: Isokinetic assessment of thigh muscle strength is frequently applied to assess the risk of injury. Similarly, trunk muscle strength and a well-developed dynamic balance are considered beneficial with regard to sports performance and injury prevention. The aim of the present study was to assess leg and trunk muscle strength as well as dynamic balance in high-level female football players of different age groups over the course of a competitive season. Methods: 45 female soccer players of a high-level Swiss football club (under-16: N=19; age = 15.0 (SD 0.7) years; body mass = 54.6 (5.8) kg; under-18: N=15; age = 16.8 (0.6) y; body mass = 59.9 (8.0) kg; body fat = 18.4 (8.8)%; adult players: N=11; age = 21.2 (2.4) y; body mass = 61.1 (6.1) kg) participated. 26 (58%) of these players were tested twice (under-16: N=10; under-18: N=10; adults: N=6), at the end of the pre-season (November 2014) as well as at the end of the second leg of the season (May 2015). Hamstrings (H) and quadriceps (Q) strength was measured on an isokinetic device (IsoMed 2000) at a speed of 60°/sec, 240°/sec and -30°/sec (eccentric). H:Q-ratio was calculated at 60°, 240° and -30°/240° (Croisier et al., 2003). Ratios between flexion/extension and rotation were calculated for trunk strength measures. Dynamic balance performance was assessed by means of the Y-balance test. Results: Quadriceps strength in the preferred leg was higher in all age-categories for flexion (60°, under-16: +11% (p=0.004); under-18: +10% (p=0.004); adults: +10% (p=0.007) and extension (i.e. 60°, under-16: +4% (p=0.31); under-18: +7% (p=0.09); adults: +3% (p=0.27)) as compared to the non-preferred leg. H:Q-ratio also showed higher values in the preferred leg. Trunk strength and flexion-to-extension-ratios rose with age (under-16: 1.59 (0.28); under-18: 1.68 (0.21); adults: 1.86 (0.14)). Balance performance showed no differences between age groups and legs (p>0.75). An increase from pre- to post-season was found for knee extension peak torque (60°, preferred leg: +12% (p=0.001); non preferred leg: +10% (p=0.08)) in the under-16 players. Discussion: Our results show an inconsistent development in leg and trunk strength over age categories. However, players showed only small differences from pre- to postseason. H:Q ratios as well as the balance score developed differently in preferred and non-preferred leg. Whether strength and balance imbalances are potentially harmful cannot be clarified by our data. However, in order to prevent injuries and to detect maldevelopment timely, regular strength and balance assessment is advisable.
© Copyright 2016 21st Annual Congress of the European College of Sport Science (ECSS), Vienna, 6. -9. July 2016. Veröffentlicht von University of Vienna. Alle Rechte vorbehalten.