Martin Behrens1, Anett Mau-Moeller2, Karoline Mueller3, Sandra Heise4, Martin Gube4, Nico Beuster4, Philipp K E Herlyn5, Dagmar-C Fischer3, Sven Bruhn4. 1. Department of Exercise Science, University of Rostock, Germany. Electronic address: martin.behrens@uni-rostock.de. 2. Department of Orthopaedics, University Medicine Rostock, Germany. 3. Department of Pediatrics, University Medicine Rostock, Germany. 4. Department of Exercise Science, University of Rostock, Germany. 5. Department of Traumatology, Hand and Reconstructive Surgery, University Medicine Rostock, Germany.
Abstract
OBJECTIVES: This study investigated effects of plyometric training (6 weeks, 3 sessions/week) on maximum voluntary contraction (MVC) strength and neural activation of the knee extensors during isometric, concentric and eccentric contractions. DESIGN:Twenty-seven participants were randomly assigned to the intervention or control group. METHODS:Maximum voluntary torques (MVT) during the different types of contraction were measured at 110° knee flexion (180°=full extension). The interpolated twitch technique was applied at the same knee joint angle during isometric, concentric and eccentric contractions to measure voluntary activation. In addition, normalized root mean square of the EMG signal at MVT was calculated. The twitch torque signal induced by electrical nerve stimulation at rest was used to evaluate training-related changes at the muscle level. In addition, jump height in countermovement jump was measured. RESULTS: After training, MVT increased by 20Nm (95% CI: 5-36Nm, P=0.012), 24Nm (95% CI: 9-40Nm, P=0.004) and 27Nm (95% CI: 7-48Nm, P=0.013) for isometric, concentric and eccentric MVCs compared to controls, respectively. The strength enhancements were associated with increases in voluntary activation during isometric, concentric and eccentric MVCs by 7.8% (95% CI: 1.8-13.9%, P=0.013), 7.0% (95% CI: 0.4-13.5%, P=0.039) and 8.6% (95% CI: 3.0-14.2%, P=0.005), respectively. Changes in the twitch torque signal of the resting muscle, induced by supramaximal electrical stimulation of the femoral nerve, were not observed, indicating no alterations at the muscle level, whereas jump height was increased. CONCLUSIONS: Given the fact that the training exercises consisted of eccentric muscle actions followed by concentric contractions, it is in particular relevant that the plyometric training increased MVC strength and neural activation of the quadriceps muscle regardless of the contraction mode.
RCT Entities:
OBJECTIVES: This study investigated effects of plyometric training (6 weeks, 3 sessions/week) on maximum voluntary contraction (MVC) strength and neural activation of the knee extensors during isometric, concentric and eccentric contractions. DESIGN: Twenty-seven participants were randomly assigned to the intervention or control group. METHODS: Maximum voluntary torques (MVT) during the different types of contraction were measured at 110° knee flexion (180°=full extension). The interpolated twitch technique was applied at the same knee joint angle during isometric, concentric and eccentric contractions to measure voluntary activation. In addition, normalized root mean square of the EMG signal at MVT was calculated. The twitch torque signal induced by electrical nerve stimulation at rest was used to evaluate training-related changes at the muscle level. In addition, jump height in countermovement jump was measured. RESULTS: After training, MVT increased by 20Nm (95% CI: 5-36Nm, P=0.012), 24Nm (95% CI: 9-40Nm, P=0.004) and 27Nm (95% CI: 7-48Nm, P=0.013) for isometric, concentric and eccentric MVCs compared to controls, respectively. The strength enhancements were associated with increases in voluntary activation during isometric, concentric and eccentric MVCs by 7.8% (95% CI: 1.8-13.9%, P=0.013), 7.0% (95% CI: 0.4-13.5%, P=0.039) and 8.6% (95% CI: 3.0-14.2%, P=0.005), respectively. Changes in the twitch torque signal of the resting muscle, induced by supramaximal electrical stimulation of the femoral nerve, were not observed, indicating no alterations at the muscle level, whereas jump height was increased. CONCLUSIONS: Given the fact that the training exercises consisted of eccentric muscle actions followed by concentric contractions, it is in particular relevant that the plyometric training increased MVC strength and neural activation of the quadriceps muscle regardless of the contraction mode.
Authors: Rodrigo Ramirez-Campillo; Cristian Álvarez; Antonio García-Hermoso; Robinson Ramírez-Vélez; Paulo Gentil; Abbas Asadi; Helmi Chaabene; Jason Moran; Cesar Meylan; Antonio García-de-Alcaraz; Javier Sanchez-Sanchez; Fabio Y Nakamura; Urs Granacher; William Kraemer; Mikel Izquierdo Journal: Sports Med Date: 2018-05 Impact factor: 11.136
Authors: Elena Monti; Martino V Franchi; Francesca Badiali; Jonathan I Quinlan; Stefano Longo; Marco V Narici Journal: Front Physiol Date: 2020-08-04 Impact factor: 4.566
Authors: Mehrez Hammami; Nawel Gaamouri; Katsuhiko Suzuki; Ridha Aouadi; Roy J Shephard; Mohamed Souhaiel Chelly Journal: Int J Environ Res Public Health Date: 2020-10-27 Impact factor: 3.390