This study aimed to establish the effect of age and pubertal development on relative peak torque in youth footballers. One hundred and fifty-seven subjects were arranged into U12-U18 age groups; of these 133 also completed a self-reporting measure of pubertal development (PDS) and were grouped accordingly. Bilateral isokinetic testing included mean peak torque/body weight (PT/BW) and angle of peak torque (AoPT) for reps 2-4 of 5 in concentric quadriceps (CQ), concentric hamstrings (CH) and eccentric hamstrings (EH) at 60 degrees s(-1). Two minutes rest were provided between concentric and eccentric tests for both legs. A significant increase with age was noted for PT/BW in CQ, CH and EH (P<0.05), although POST HOC analyses revealed different patterns of significance dependent upon muscle and type of contraction. Specifically, the U18 s (CQ:2.20 nm/kg, CH:1.39 nm/kg, EH:2.16 nm/kg) were not significantly stronger than the U16 s and U15 s (CQ:2.42/2.29 nm/kg, CH:1.41/1.27 nm/kg, EH:2.22/2.15 nm/kg) even though they had entered full time training. The relationship between EH PT/BW and AoPT showed a weak but significant inverse correlation (P<0.001; R= -0.390 and -0.346 for dominant and non dominant legs). The findings of this study present unique football specific normative and age/PDS group data for PT/BW and AoPT, and the corresponding relationship between these variables.

This study aimed to analyse the effect of age on muscle peak torque (PT), and Hamstring (H): Quadricep (Q) ratio in elite youth footballers. To date, no study has considered age-group playing level and pubertal development in this population. One hundred and fifty-seven elite youth footballers in the age groups U12 to U18 volunteered to participate in this study, 133 of these were further grouped for pubertal development. Prior to testing subjects completed separate familiarisation, a three minute cycle ergometer warm up (resistance 50-60W), and two sub-maximal repetitions. Concentric and eccentric isokinetic PT measures for reps 2-4 of H and Q muscle action were taken at 60 degrees s (-1). From this, conventional and functional H: Q ratio was calculated along with dominant: non dominant ratio for the concentric Q and H, and eccentric H conditions. Significant main effects were observed for the age/pubertal development group and PT in all muscles and conditions (P<0.05). Of particular interest was a significant main effect for age and Functional H: Q (P<0.05), which suggested a move away from equality at U18. Our study provides normative data for coaches, trainers and clinicians working with youth footballers and may also have connotations for injury prevention and performance.