Reliability of Lower-Limb Strength Tests According to Maturity Status in Young Male Elite Football Players

Lower-limb strength assessment is essential for talent identification, training program design, and return-to-play decisions. However, the influence of biological maturity on test reliability remains unclear, particularly in prepubertal players whose motor coordination is still developing. This study examined the test-retest reliability of dominant-limb abduction, adduction, and anterior and posterior chain tests in elite youth football players, and compared reliability across maturity stages and movement types.

Seventy academy players were divided into 3 groups: 24 prepubertal, 18 pubertal, and 28 postpubertal. Following at least 2 familiarization sessions, players performed 5 maximal isometric strength tests on 2 occasions 1 week apart. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated for each test, and statistical comparisons between maturity groups were performed using the Modified Signed-Likelihood Ratio Test (for CVs) and Fisher Z transformation (for ICCs).

Most tests demonstrated good to excellent reliability across all maturity levels (CV < 10%, ICC > .90). However, postpubertal players exhibited significantly lower CVs and higher ICCs than prepubertal players in several tests, particularly for polyarticular standing posterior chain movements (P < .05). No significant differences were observed between prepubertal and pubertal players.

These results indicate that test reliability improves with biological maturity, likely due to enhanced motor coordination and movement control. Consequently, the reliability of lower-limb strength assessments is not interchangeable between maturity categories, and results should be interpreted with caution when used for talent identification or long-term player monitoring in elite youth football players.