Abstract

Given the nature of plyometric exercises (which overload muscles and joints), intensity control plays an important role in training. Therefore, the aim of this study was to determine the effect of drop height and mass changes on exercise intensity expressed through ground reaction forces (GRF) and the rate of eccentric force development (E-RFD). Nine elite male athletes representing 1st league athletics clubs volunteered to serve as subjects for the study. They performed unloaded and loaded drop jumps from 0.2 m, 0.4 m and 0.6 m. As for loaded jumps, loads constituted 5% and 10% of body mass (BM). It was observed that with an increase in drop height, the values of ground reaction forces at the first peak (the contact of toes with the ground; GRF1) and at the second peak (the contact of heels with the ground; GRF2) as well as the values of E-RFD1 (measured from 0 to GRF1) and E-RFD2 (measured from 0 to GRF2) increased significantly (P<0.01). An increase in BM from 5 to 10% led to a change in the values (P<0.05) of GRF1, GRF2 and E-RFD1 but only in the case of drop jumps from 0.6 m. However, the values of these parameters in loaded drop jumps with 10% BM were lower than those with 5% BM. The study results indicate that a change in drop height is a more effective way to manipulate the intensity of drop jumps than a change in body mass. Verf.-Referat