Immediate Effect of Vibrating Foam Roller on the EMG Amplitude of Muscle Hamstring of Healthy Subject with Hamstring Tightness

Abstract

Hamstring tightness is the reduction of the hamstring muscle's ability to lengthen from a neutral position accompanied by a feeling of limitation or discomfort in the posterior thigh. Shortening of the hamstring can cause misalignment of the trunks, reduce neuromuscular efficiency, increase energy expenditure, and excessive strain to the knee joint. Foam rolling can improve joint range of motion, neuromuscular function, reduce muscle and myofascial pain and regulate muscle tone. The aim of this study was to assess the immediate effect of vibrating foam roller on the hamstring muscle's EMG amplitude in healthy subjects with hamstring tightness. The subjects of this study were 14 healthy males age 20-45 years, with hamstring tightness (KEA >20°). They divided into 2 groups, the Vibrating Foam Roller (VFR) group and the Non-Vibrating Foam Roller (NVFR) group. The outcome measured is the amplitude of maximum isometric contraction of Biceps femoris (BF) and Semitendinosus (ST) in knee flexion angle 30 and 90 recorded by surface EMG. The VFR group showed increase of BF30 197,23+26,27 (p value = 0,016) BF90 174,26+46,72 (P value= 0,033) and ST90 197,48+18,36 (p value=0,005). NVFR group showed decrease of BF30 130,9+24,18 (p value = 0,07) BF90 116,09+33,71 ST30 144,63+28,67 (p value 0,685) and ST90 155,63+53,07 (p value 0,526). The Δ amplitude EMG results between the two groups were significant difference in BF30 (p value = 0,002) and BF90 (p value = 0,001). This study concluded that vibrating foam roller significantly increased the hamstring muscle's EMG amplitude.