Normative Concentric Knee Torque Values and Performance Categories in Male Soccer Players Aged 15–17 Years

Isokinetic dynamometry is widely used to evaluate knee strength and muscular balance, yet normative benchmarks for late-adolescent soccer players are lacking. The present study establishes comprehensive age-specific reference values for concentric quadriceps and hamstring torque performance in male soccer players aged 15–17 years tested at both 60°·s−1 and 300°·s−1 using a HUMAC Norm dynamometer. The 60°·s−1 testing included 502 players (15 years, n = 106; 16 years, n = 175; 17 years, n = 221), while the 300°·s−1 testing was performed on a voluntary subsample of 260 players (15 years, n = 49; 16 years, n = 74; 17 years, n = 137) drawn from the same cohort. Torque was expressed in absolute (Nm) and body-mass normalized (Nm∙kg−1) values, converted into z-scores and T-scores [T = 50 + (10 × z)], and classified into performance categories ranging from very low to very high. Age effects were tested with one-way analysis of variance (ANOVA). It was indicated that across all age groups, most players (60–74%) showed average torque performance, with smaller proportions classified as high (9–19%), low (10–17%), very high (<5%), and very low (<3%). Mean values (at 60°·s−1 ) increased from the age of 15 to 16 and plateaued by the age of 17, suggesting near-mature neuromuscular development. Until now, these data provide one of the largest age-specific benchmarks available for late adolescent soccer players, addressing a gap between existing pediatric and adult reference standards. These dual-velocity normative datasets provide unique reference bands that enable precise classification of performance, aiding in screening, load monitoring and rehabilitation.