Effects of different strengthening methods on hamstring muscle group's passive mechanical properties in healthy individuals

Uysal Ö., Effects Of Different Strengthening Methods On Hamstring Muscle Group's Passive Mechanical Properties In Healthy Individuals. Graduate School of Health Sciences, Sport Physiotherapy Master's Degree Thesis, Ankara, 2018. The purpose of this study was to investigate effects of different strengthening methods on hamstring muscle group's passive mechanical properties and to investigate this effect's relation with performance changes in healthy individuals. 42 healthy sedantary male participated in this study. Passive mechanical properties and strength of hamstring and quadriceps muscles, flexibility of hamstring muscles, anaerobic exploseive strength, reaction time, agility were measured. Participants randomized evenly into one of three groups; eccentric, concentric and NMES. After 8 weeks training period, participants were measured again. While concentric training increased bilateral hamstring and quadriceps stiffness, it decreased bilateral quadriceps tonus. When compared to other groups, concentric training increased bilateral hamstring stiffness more significant then others (dominant p=0.005 and non-dominant p=0.012). Also, dominant side quadriceps tonus decreased more significantly then eccentric training group (p=0.01). Concentric group increased bilateral quadriceps stiffness more significantly then other groups (Comparing with others, dominant and non-dominant comparision values are given in order; Eccentric p=0.003 and p=0.005; NMES p=0.003 and p=0.004). Eccentric training increased bilateral hamstring elasticity (dominant p=0.0445 and non-dominant p=0.0092) and decreased quadriceps stiffness (dominant p=0.0478 and p=0.028). Eccentric training's effect on non-dominant hamstring elasticity was more significant then NMES training (p=0.008). In concentric training group, significant correlation found between decrease in dominant side quadriceps tonus and decrease in reaction timing (r=0.664 ve p=0.026); increase in non-dominant side quadriceps stiffness and decrease in reaction timing (r=-0.664 ve p=0.026). Significant correlations between increase in muscle strength and passive mechanical properties was found majorly in concentric training group. In light of current evidence, there is no single training method that is optimum for muscle's passive mechanical properties. Concentric training can be favourable for increasing muscle's stifness, whereas eccentric training should be the choice in order to increase muscle elasticity. Evaluating muscle's passive mechanical properties and then deciding training modalities based on the need could be an important approach for hamstring in preventive physiotherapy and on increasing performance. Keywords: Hamstring Muscle Group, Elektrical Stimulation, Resistance Training, Muscle tonus.