Evaluation of muscular activation of lower extremity muscular activation for different jumping and landing techniques in volleyball players

The aim of this study was to determine the muscular activation strategies for different jumping and landing techniques in volleyball players via electromyography (EMG).Muscular activation of vastus medialis, vastus lateralis, gluteus maximus, gastrocnemius and biceps femoris were measured in countermovement (hands free), countermovement jump, squat jump, block landing (40 and 60 cm), and spike landing (40 and 60 cm) between volleyball players and control group. Maximal voluntary contractions of muscles were determined with maximal isometric contractions for data normalizing. Integral and linear envelope analyses were used for muscular activation analyses depend on the data. Jumping was analyzed in three phases; propulsion, flight and landing. The pre-activation before landing of volleyball players were more than control group (p<0.05). The landing activation in control group was more than volleyball players (p<0.05). The pre-activation before landing causes a reduction of load on joints and muscles during the landing. Landing technique differences can be explained with this landing muscular activation.Volleyball players had more biceps femoris muscular activation than control group in the propulsion phase (p<0.05). This result showed that volleyball players had higher agonist-antagonist contraction ratio than control group.Muscular activations were analyzed for comparing the squat and countermovement jump. There were more muscular activations in the propulsion phase for vastus medialis, vastus lateralis and gluteus maximus in countermovement jump than squat jump (p<0.05). There was no significant difference in muscular activations between two groups in landing and post landing.In conclusion this study results stated that volleyball players had more intramuscular coordination than control group and it is one of the factors that effects the jumping performance depend on the results.Key Words: Electromyography, Muscular Activation, Squat Jump, Countermovement Jump