Variable Heights Influence Lower Extremity Biomechanics and Reactive Strength Index during Drop Jump: An Experimental Study of Male High Jumpers

Table 1

Quadratic polynomial regression analysis for variables during DJs.

S. no.	Variables	R	R^2	Adjusted R^2	F	β	t		Constant
1	vGRF	0.686	0.471	0.457	33.852	8.149	7.233	≤0.001	27.742
2	vGRFep	0.54	0.292	0.273	15.667	−7.275	−3.958	≤0.001	63.006
3	Hip extension moment	0.114	0.013	−0.013	0.5	0.09	0.707	0.484	1.43
4	Knee extension moment	0.281	0.079	0.055	3.26	0.158	1.806	0.079	3.106
5	Ankle plantarflexion moment	0.171	0.029	0.004	1.141	0.111	1.068	0.292	3.035
6	Lower limbs’ support moment	0.35	0.123	0.1	5.314	0.359	2.305	0.027	7.571
7	Eccentric power of the hip joint	0.49	0.24	0.22	12	−9.883	−3.464	0.001	−4.342
8	Eccentric power of the knee joint	0.676	0.457	0.443	31.985	−6.142	−5.656	≤0.001	−8.729
9	Eccentric power of the ankle joint	0.531	0.282	0.263	14.946	−3.563	−3.866	≤0.001	−4.465
10	Concentric power of the hip joint	0.589	0.347	0.33	20.171	3.556	4.491	≤0.001	4.519
11	Concentric power of the knee joint	0.119	0.014	−0.012	0.547	0.457	0.739	0.464	19.267
12	Concentric power of the ankle joint	0.046	0.002	−0.024	0.081	0.202	0.284	0.778	22.514
13	RSI	0.064	0.004	−0.022	0.155	0.002	0.393	0.696	0.156

vGRF: the peak of vertical ground reaction force; vGRFep: the peak of vertical ground reaction force in the extension phase; RSI: reactive strength index. indicates significant effects, and bold is used to indicate it, which means drop height significantly affects the indicator.