Hip adduction and abduction isometric force production in young football players: reliability of different testing protocols

We examined the reliability of five hip adduction and abduction isometric strength testing protocols in young football (soccer) players. Maximal hip adduction and abduction isometric strength was measured in 20 Academy professional male football players from a youth team within (12 ± 4 min) and between (after one week) two sessions over five protocols available from a frame-stabilized dynamometer, specifically: short-lever (SL) lying at 45°, 60°, and 90° hip flexion (SL45, SL60 and SL90, respectively), short-lever standing (SLS) and long-lever standing (LLS). All testing protocols reported good to excellent reliability (ICC = 0.84–0.99), except for the moderate between-session reliability of hip abduction force LLS (ICC = 0.52–0.59). The SLS and the LLS protocols produced the greatest and the lowest adduction, respectively (d = 0.45–0.61). Similarly, the SLS and the LLS protocols produced the greatest (d = 0.22–0.35), and the lowest (d = 0.19–0.54) abduction force, respectively. No significant differences were observed between the SL45, SL60 and SL90 protocols. All short-lever adduction and abduction protocols showed moderate-to-excellent levels of reliability. The lower reliability levels and force produced by the LLS protocol suggest that short-lever testing protocols should be preferred to test hip adduction or abduction strength in young football players.