Stiffness, intralimb coordination, and joint modulation during a continuous vertical jump test

Abstract

This study analysed the modulation of jump performance, vertical stiffness as well as joint and intralimb coordination throughout a 30-s vertical jump test. Twenty male athletes performed the test on a force plate while undergoing kinematic analysis. Jump height, power output, ground contact time, vertical stiffness, maximum knee and hip flexion angles, and coordination by continuous relative phase (CRP) were analysed. Analysis of variance was used to compare variables within deciles, and t-tests were used to compare CRP data between the initial and final jumps. Results showed reduction in jump height, power output, and vertical stiffness, with an increase in contact time found during the test. Maximum knee and hip flexion angles declined, but hip angle decreased earlier (10-20% of the test) than knee angle (90-100%). No changes were observed in CRP for thigh-leg coupling when comparing initial and final jumps, but the trunk-thigh coupling was more in-phase near the end of the test. We conclude that fatigue causes reduction in jump performance, as well as changes in stiffness and joint angles. Furthermore, changes in intralimb coordination appear at the last 10% of the test, suggesting a neuromotor mechanism to counterbalance the loss of muscle strength.

Functional Exercise Training and Undulating Periodization Enhances the Effect of Whole-Body Electromyostimulation Training on Running Performance

“…This fact could be explained by differences in the exercises used and the electrical parameters applied in both intervention groups (e.g., the inclusion of several plyometric exercises in the PFG). Since the main difference between CMJ and ABJ is the contribution of interlimb coordination, the improvement obtained in ABJ in the PFG when compared to the TG, suggest that a periodized and functional WB-EMS training program could have a considerable impact on inter-limb coordination (Dal Pupo et al, 2013 ). However, more studies are needed to elucidate which physiological or biomechanical mechanism may explain the differences reported between groups.…”

Simulating fatigue in squat jumps: A preliminary investigation

“…Kinetic and kinematic changes in jumping performance have been observed with various loads and amounts of fatigue. [1][2][3][4] Research has shown that adding a load of 20 kg was enough to statistically alter the force, velocity, power and displacement in untrained individual's squat jump performance. 1 The previously mentioned sample had a mean body mass of 80.8 kg, therefore the 20 kg load represented an additional mass of 24.75%, causing decrements of 13.69% in peak power and 22.22% in jump height.…”

“…Fatigue may be accompanied by decreases in jump height, flight time, eccentric force production, power, vertical stiffness, and knee flexion angles. [4][5][6] Fatigue has also been associated with increases in ground contact time and with decreases in angular velocities and accelerations in jumps. 4,[6][7] Furthermore, fatigue has been associated with knee joint stability decreases, that may increase the risk of injury in both males and females.…”

“…[4][5][6] Fatigue has also been associated with increases in ground contact time and with decreases in angular velocities and accelerations in jumps. 4,[6][7] Furthermore, fatigue has been associated with knee joint stability decreases, that may increase the risk of injury in both males and females. 8,9 The above-mentioned research has shown that performance decreases in loaded conditions and in fatigued situations.…”

Bat swing mechanical analysis with an inertial measurement unit: reliability and implications for athlete monitoring

“…11 Similarly, alterations in bat position throughout a swing may be related to onset or accumulation of fatigue. But similar to bat swing velocity, more research is required to validate this speculation.…”