Effect of 2 different jump types on vertical leg stiffness and performance parameters in healthy young women

Background and Aim: To investigate effects of 2 different jump types on vertical leg stiffness and performance parameters in healthy young women. People usually use various types of high jumping. It seems any model may have different effects on biomechanical parameters of the human body. Present study determined the effect of 2 jump types on performance parameters and vertical leg stiffness as a mechanical response of body to perturbations which occur during jumping. Materials and Methods: Vertical leg stiffness and performance parameters (jump height, flight time, contact time and power) were calculated in 25 healthy female subjects, under 2 conditions of Squat Jump (SJ) and Counter Movement Jump (CMJ). Results: Vertical leg stiffness (P= 0.028) and jump height (P= 0.039) were significantly higher in CMJ than SJ. Jump type has not any significant effects on the flight time (P= 0.1), contact time (P= 0.7) and power (P= 0.3). Conclusion: Counter movement jump increases the muscle force production, work output and GRF and may cause improvement in jump performance. Increased vertical leg stiffness improves performance as well as the risk of injury. Key words: Vertical leg stiffness, Performance, Vertical jump, Force plate