Countermovement jump propulsive kinetics distinguish young weightlifters who attain national qualification

Researchers have explored the relationship between force-generating abilities and weightlifting performance in young athletes, but it remains unclear whether isometric mid-thigh pull (IMTP) and countermovement jump (CMJ) kinetics can distinguish between those who achieve national qualification and those who do not. This study aimed to (i) compare IMTP and CMJ kinetics between young weightlifters who did and did not attain national qualification, and (ii) identify kinetic variables that predict qualification. Thirty-seven young weightlifters were classified into two groups: those who qualified (QUAL; age = 17 .1 ± 0.3 years, maturity offset
= 3.13 ± 0.6 years, males= 15, females= 10) and those who did not qualify (DNQ; age= 15.8 ± 2.2 years, maturity offset = 2. 7 ± 1.6 years, males = 6, females = 6). Participants completed CMJ and IMTP tests on dual force plates. T-tests revealed that QUAL showed significantly (p < 0.05) higher relative force at minimum displacement (g = 0.82), average relative propulsive force (g = 1.76), and average propulsive velocity during the CMJ (g = 0.68), along with a shorter propulsive phase (g = -1.22). In the IMTP, QUAL demonstrated higher relative peak force. Statistical parametric mapping revealed greater relative vertical force at 69-88% of
movement time in QUAL, indicating higher force during the CMJ propulsive phase. Binary logistic regression identified CMJ average relative propulsive force and propulsive phase duration as significant predictors of qualification, with strong predictive accuracy (AUC = 0.910, p < 0.05 and AUC = 0.807, p < 0.05), highlighting the value of these variables when identifying and developing young weightlifters for national qualification