Short-term changes of the static stretching, electromyoestimulation and whole-body vibration on the flexibility of hamstrings

Aim. The purpose of this study was to investigate the acute effects of the static stretching (SS), neuromuscular electrical stimulation (NEMS), wholebody vibration (WBV) and the combination of all these protocols (WBV+NEMS) on the flexibility of hamstrings. Methods. Fifteen males received four stretching protocols in a crossover design, one protocol per week: static stretching (SS); stretching with superimposed NEMS; stretching combined with WBV; and stretching with superimposed NEMS combined with WBV (WBV+NEMS). All protocols lasted one minute. The flexibility was assessed by both the Back Saver Sit and Reach (BSSR) and the Active Knee Extension (AKE) test. Flexibility measurements were performed before (baseline), immediately after the protocol (post) and 1, 3, 5 and 10 min post protocol. Outcomes. The BSSR at post was greater than the baseline value for NEMS (18.3%, p<0.001), WBV (10.1%, p<0.05), and WBV+NMES (14.9%, p<0.01). Ten minutes after the application of each protocol the BSSR was higher in respect to baseline value for SS (12.0%, p<0.001), NMES (18.8%, p<0.001), WBV (12.7%, p<0.01), and WBV+NEMS (13.6%, p<0.001). All protocols improved AKE in the same way. Conclusion. Our data indicates that SS, NEMS, WBV and the combination of both methods are effective to improve the flexibility of hamstrings. Furthermore, this improvement may be maintained for at least 10 min after the cessation of the exercise, irrespectively of the stretching protocol. Key words: Muscle stretching exercises, proprioception, training, electric stimulation, vibration.