Reliability of two-dimensional kinematic assessment of single-leg landing, countermovement jump, and broad jump technique among elite handball players

The aims of this study were: a) to assess the intra-session reliability of two-dimensional kinematic variables related to the knee, hip, and trunk joints, and b) to compare the results between subjectively and objectively identified key movement positions in single-leg countermovement jumps (SLCMJ), single-leg broad jumps (SLBJ), and single-leg drop landings. Eighty elite handball players (mean age 21.8 years; weight 92.0 kg; height 1.9 m) participated in the study. Three repetitions of each test, using both the dominant and non-dominant legs, were video recorded from lateral and frontal planes. Kinematic analysis was performed manually using Kinovea software. Inclinations of the shin, thigh, pelvis, and trunk (absolute variables) were calculated based on anatomical landmarks, along with joint angles (relative variables). Key movement positions were identified subjectively by expert assessment and objectively by the time point of the highest vertical ground reaction force for each task. The results indicated moderate-excellent reliability for drop landing test (ICC = 0.54-0.99), moderate-good reliability (ICC = 0.51-0.83) for SLCMJ, and poor-moderate reliability for SLBJ in both the push off (ICC = 0.01-0.81) and landing phases (ICC = 0.10-0.86). Significant differences were found between the results from subjective and objective key movement position identification (p < 0.05).