The purpose of the study was to examine the acute effects of different dynamic exercise interventions on hamstring muscle performance. Thirty-six young men with poor hamstring flexibility were randomly assigned to three intervention groups: jogging combined with dynamic open kinetic chain stretching (DS), jogging combined with dynamic closed kinetic chain stretching (lunge with eccentric hamstring windmills, LEC), and jogging only (CON) groups. Hamstring flexibility, muscle stiffness (area under the curve, AUC), joint position sense (JPS), maximal eccentric strength (ECC), and angle of peak torque (APT) were recorded before and immediately after the exercise interventions. The results showed that the hamstring flexibility increased in DS (p < 0.001); muscle stiffness decreased in DS and was lower than jogging (p < 0.001). Moreover, ECC increased in LEC and was higher than jogging and DS (p < 0.001). APT was different among 3 groups (p < 0.001). Decreased accuracy of JPS was found in DS and jogging (p < 0.001). In conclusion, the dynamic closed kinetic chain stretching (LEC) as compared to open kinetic chain stretching (DS) or jogging group, may be an effective technique to enhance muscle performance during the pre-competition warm-up routine.

To examine whether adding preconditioning hamstring resistance exercises to a regular warm-up prior to a repeated sprinting exercise provides protection against the sprinting-induced muscle damage. Ten female soccer players (mean ± SD age: 21.3 ± 4.5yrs; height: 171.34 ± 8.29 cm; weight: 68.53 ± 11.27 kg) participated in this study. After the familiarization visit, the subjects completed three separate randomly sequenced experimental visits, during which three different warm-up interventions were performed before the muscle-damaging protocol (12 sets of 30-m maximal repeated sprints): 1. Regular running and static stretching (Control); 2. Control with hyperextensions (HE); 3. Control with single leg Romanian deadlift (SLRD). Before (Pre), immediately (Post0), 24 hours (24hr), and 48 hours after (48hr) the sprints, hamstring muscle thickness, muscle stiffness, knee flexion eccentric peak torque, knee extension concentric peak torque, and functional hamstring to quadriceps ratios were measured. Repeated sprints have induced muscle damage (e.g., an average of 42% knee flexion eccentric strength reduction) in all three conditions. After the SLRD, hamstring muscle thickness decreased from 24hr to 48hr (p < 0.001). Additionally, muscle stiffness and eccentric strength for the SLRD showed no difference from baseline at 24hr and 48hr, respectively. When compared with the SLRD at 48hr, the muscle stiffness and the eccentric strength were greater and lower, respectively, in other protocols. The SLRD protocol had protective effect on sprinting-induced muscle damage markers than other protocols. Athletes whose competitions/training are densely scheduled may take advantage of this strategy to facilitate muscle recovery.

Kinesiology tape (KT) has been widely used in the areas of sports and rehabilitation. However, there is no gold standard for the tape tension used during a KT application. The purpose of this study was to examine the effects of KT application with different tension intensities on soleus muscle Hoffmann-reflex (H-reflex) modulation during lying and standing postures. Fifteen healthy university students were tested with 3 tape tension intensities during separate visits with a randomized sequence: tape-on no tension (0KT), moderate (about 50% of the maximal tape tension: (ModKT), and maximal tape tension (MaxKT). During each experimental visit, the H-reflex measurements on the soleus muscle were taken before, during, and after the KT application for both lying and standing postures. The Hwave and M-wave recruitment curves were generated using surface electromyography (EMG). There was a main effect for posture (p = 0.001) for the maximal peak-to-peak amplitude of the H-wave and M-wave (H max /M max) ratio, showing the depressed H max /M max ratio during standing, when compared to the lying posture. Even though the tension factor had a large effect (η p 2 = 0.165), different tape tensions showed no significant differential effects for the H max /M max ratio. The spinal motoneuron excitability was not altered, even during the maximal tension KT application on the soleus muscle. Thus, the tension used during a KT application should not be a concern in terms of modulating the sensorimotor activity ascribed to elastic taping during lying and standing postures.