Influences of tendon stiffness, joint stiffness, and electromyographic activity on jump performances using single joint

Abstract

The present study aimed to examine the influences of tendon stiffness, joint stiffness, and electromyographic activity on jump performances consisting of a single-joint movement. Twenty-four men performed three kinds of unilateral maximal jump using only the ankle joint (squat jump: SJ; countermovement jump: CMJ; drop jump: DJ) on the sledge apparatus. The relative differences in the jump height of CMJ and DJ compared to SJ were defined as pre-stretch augmentation. During jumping exercises, electromyographic activities (mEMG) were recorded from the plantar flexors. Ankle joint stiffness was calculated as the change in the joint torque divided by the change in ankle joint angle during the eccentric phase of DJ. Achilles tendon stiffness was measured using ultrasonography during isometric plantar flexion. No significant correlations were found between joint stiffness and pre-stretch augmentation in both CMJ and DJ. On the contrary, tendon stiffness was significantly correlated with pre-stretch augmentation in both CMJ (r = -0.471) and DJ (r = -0.502). The relative mEMG value of CMJ (to that of SJ) during the concentric phase was significantly correlated with pre-stretch augmentation (r = 0.481), although this relationship was not found in DJ. These results suggested that (1) the greater jump height in CMJ could be explained by both the tendon elasticity and the increased activation level of muscle, (2) tendon elasticity played a more significant role in the enhancement of jump height during DJ, and (3) joint stiffness was not related to either pre-stretch augmentation or tendon stiffness.

Effects of static and dynamic training on the stiffness and blood volume of tendon in vivo

“…They suggested that the nervous command of contraction during the isometric training differed from that during the vertical jumping. In addition to this point, some recent observations showed that the mechanical properties of human tendon affected the performances during jumping and/or sprinting exercises (22,24,37). Among them, Kubo et al (22) reported that the tendon stiffness in knee extensors was inversely correlated with the relative difference in jump height between vertical jumps performed with and without countermovement, i.e., prestretch augmentation.…”

Current Concepts for Rehabilitation and Return to Sport After Knee Articular Cartilage Repair in the Athlete

“…While the effects of plyometric training on patients recovering from knee injuries, especially after articular cartilage repair, are unknown, it may be a critical training method to safely return athletes to full sports participation. 24,60,70,81,87,94,110,120,130,131 Because of the considerable loads and speeds applied to the healing joint with plyometric training, patients should first demonstrate the ability to tolerate the demands of daily activities without pain or swelling. 24 Clinicians must be diligent in monitoring the patient's response to training, using effusion grading and soreness rules.…”

Comparação de índices neuromusculares e fisiológicos de judocas em diferentes categorias de peso

“…A partir das amostras de sangue foram identificados o pico de concentração de lactato sanguíneo (LACmax) e o percentual de diminuição de lactato sanguíneo (DLS), conforme a equação proposta por Pelayo et al (1996) (DUGAN et al, 2004). Outro fator que pode explicar essa diferença entre as categorias é a eficiência de alguns mecanismos musculoelásticos presentes nas ações musculares realizadas, tais como o stiffness (KUBO et al, 2006) e a rapidez na transição entre as fases excêntrica e concêntrica (KOMI; GOLLHOFER, 1997). De acordo com os autores, essa transição deve ser realizada em um breve espaço de tempo, a fim de evitar a dissipação da energia elástica acumulada nas estruturas musculotendíneas.…”