The relationship between lower extremity stiffness during hopping tests with performance in vertical jumps
Poster Presentation XML
Paper ID : 1671-11THCONF
1phd student of faculty of physical education and sport sciences, kharazmi university
2full PHD
3assistant proffessor of faculty of pysical education and sport sciences, kharazmi university
Introduction: Considering that stiffness as one of the mechanical properties of viscoelastic structures of human body is an important factor in the production of motion and neurobiomechanical control of the human body and its correlation to success of some sports performances has been previously presented, the purpose of this research is to determine the relationship between stiffness with performance during vertical jumps.
Methodology: 18 male physical education students (age 24.58± 1.64 yrs, weight 65.16 ± 4.74 kg, height 1.76 ± 0.06 m) participated voluntarily in this study. To collect data using the six motion analysis cameras (Vicon, USA) and a force plate (Kistler 9281, Winterthur, Switzerlan), subjects performed Vertical hopping tests in three styles, bilateral, unilateral on dominant leg and unilateral on non-dominant leg, with three strategies, preferred and control (frequency 2.2 Hz) and the maximal, to determine the stiffness of lower extremity and performed Squat jump and Countermovement jump tests to determine the height of jump and efficiency of the stretch-shortening cycle. The correlation between lower extremity stiffness and performance of vertical jumps was determined by Pearson correlation test at a significant level of 0.05.
Results: among the stiffness variables with different strategies and styles, only the preffered unilateral lower extremity stiffness showed a significant and negative correlation with height of jump variable in both squat and countermovement jumps (P ≤ 0.05). No significant relationship was found between the lower extremity stiffness with the efficiency of stretch-shortening cycle.
Discussion: In according to research findings, we conclude that the unilateral hopping test with preferred strategy is proper test for determining stiffness in order to determine relationship between stiffness with vertical time-independent performances. less stiffness in the performance of both squat jump and countermovement jump is advantageous, but about the stretch-shortening cycle less or more stiffness is not advantageous and there may be some optimum for it.