CCD 25 - SUPLEMENTO I AÑO 10 I VOLUMEN 9 I MURCIA 2014 I ISSN: 1696-5043 NSCA IV INTERNATIONAL CONFERENCE 2014 HUMAN PERFORMANCE DEVELOPMENT THROUGH STRENGTH AND CONDITIONING S262 CCD Poster INTRODUCTION The muscle injuries on the hamstrings are among the most common in team sports such as soccer, American football, and rugby (1). In this regard, it has been report- ed that reduced flexibility may be associated with muscle strain-related injuries (2). On the other hand, previous data indicate that a stretching program helps on reducing this type of injury (3). Moreover, the use of vibrations has proved effectiveness in increasing the hamstring flexibility in a short period of time (4). Therefore, the objective of this study was to determine both acute and residual effects of high frequency vibration on the hamstrings. METHODS Seventy one sports science students (age 21 ± 2.6 years, height 1.70 ± 8.4 m, weight 57 ± 9.4 kg , fat 24 ± 4.1%) were randomly allocated into three groups: a) control, b) static flexibility without vibration (F-V), and c) static flexibility with vibration (F+V). Both vibration groups performed the task on a platform (Excel Pro, Fitvibe, Belgium). The task consisted on 3 sets of 1 min with each leg. After 1 min rest, participants were asked to reach out to the feet with both hands. The vibration intensity was set at 40Hz and 4mm. The modified Seat and Reach test (S&Rm) was used to measure the lumbar and hamstring flexibility. A goniome- ter was placed on the angle of the coxofemoral articulation of the both legs. An ANOVA with repeated measures was applied, together with the Cohen effect size. The signifi- cance was set at p< 0.05. RESULTS The results indicate that both F-V and F+V groups signif- icantly improved flexibility when compared to the control participants (p< 0.0001). The F+V group showed 1.86 cm increases in the S&Rm, and up to 1.76 cm in the coxofe- mural articulation when compared to the F-V. On the same way, F+V flexibility was less affected than F-V after 4 days after training (Cohen effect size). DISCUSSION In conclusion, an acute vibration session significantly improves hamstring flexibility and also generates an in- creased residual effect compared to F-V group. This sup- ports the use of vibration as a tool to help on preventing injuries in athletes and physically active subjects. REFERENCES 1. Rogan S, Wüst D, Schwitter T, Schmidtbleicher D. Static stretching of the hamstring muscle for injury prevention in football codes: a system- atic review. Asian Journal of Sports Medicine. 2013; 4(1):1-9. 2. Van Mechelen W, Hlobil H, Kemper HC, et al. Prevention of running injuries by warm-up, cool-down, and stretching exercises. The American Journal of Sports Medicine. 1993; 21(5):711-9. 3. McHugh MP, Cosgrave CH. To stretch or not to stretch: the role of stretching in injury prevention and performance. Scandinavian Journal of Medicine & Science in Sports. 2010; 20(2):169-81. 4. Van den Tillar R. Will whole-body vibration training help increase the range of motion of the hamstrings? The Journal of Strength & Condi- tioning Research. 2006; 20(1):192-196. ACUTE AND RESIDUAL EFFECT OF VIBRATION ON HAMSTRING FLEXIBILITY Cristi-Montero, C. 1,2 , Landahur Bustamante, I. 3 , Muñoz Figueroa, W. 3 , Olivares Galleguillos, C. 3 , Rodríguez-Rodríguez, F. 1 , Bresciani, G. 4 1 Laboratorio de Motricidad Humana, Escuela de Educación Física. Pontificia Universidad Católica de Valparaíso, Chile. 2 Facultad de Educación, Universidad Autónoma de Chile. 3 Pedagogia en Educacion Fisica, Universidad Viña del Mar, Chile. 4 Facultad de Ciencias de la Salud, Universidad Autónoma de Chile. carlos.cristi.montero@gmail.com