Lower limb strength and training experience in elite and sub-elite female footballers

BACKGROUND: Strength differences between performance levels remain unclear in female football. Furthermore, the relationship between fulltime training and strength has been unexplored despite increased professionalisation in the sport. OBJECTIVE: The aims of this research were to examine knee flexor/extensor and hip adductor/abductor strength differences between elite and sub-elite female footballers, and then determine the relationship of strength performance to age, years of football experience (FE), and years of fulltime training (FTT). METHODS: 15 elite and 15 sub-elite professional female footballers were tested. The main outcomes were concentric isokinetic knee flexor and extensor peak moment at 60, 180, and 300∘/s, and isometric hip adductor (ADD) and abductor (ABD) force. RESULTS: The elite team had higher absolute (300∘/s: 47.13–49.33 Nm vs 37.33–38.93 Nm, p< 0.05) and normalised (300∘/s: 0.76–0.80 Nm/kg vs 0.59–0.62 Nm/kg, p< 0.05) knee flexor values, and higher normalised ADD (5.64–5.66 N/kg vs 4.98–5.05 N/kg, p< 0.05) and ABD force (5.80–6.00 N/kg vs 5.26–5.39 N/kg, p< 0.05), compared to the sub-elite team. Age, FE, and FTT were correlated to knee flexor values (r= 0.381–0.559, p< 0.05). Additionally, FTT was correlated with normalised ADD and ABD force (r= 0.362–0.546, p< 0.05). CONCLUSION: Sub-elite female footballers may require additional knee flexor and hip strengthening in order to make the step up to the elite level. Those who are younger or have low FTT may also be recommended additional lower limb strengthening ahead of joining a fulltime training environment.