Effect of different stretching durations on posterior thigh muscle flexibility

Abstract

Muscle stretching is one of the most used techniques for increasing range of movement (ROM), but there is no consensus on how long it must last to increase flexibility. The aim of this study was to determine which stretching duration is most effective. Flexibility was assessed by measuring the popliteal angle (PA). Thirty mean age 21.1±2.9 year-old female volunteers were recruited and randomly divided into five groups (control, 15, 60, 90, and 120 seconds). All underwent a four-week passive stretching program at these different stretching lengths. Each was assessed as to flexibility by three clinical examiners who measured the PA. Data were statistically analysed, with significance level set at p<0.05; inter-examiner reliability was assessed by the intraclass correlation coefficient (ICC) and the values found pointed to high reproducibility (ICC 0.985). Results show significant differences between the 15- and 120-second groups (p<0.01) and between 90- and 120-second groups (p<0.05) - both groups where ROM increase was higher. The 120-s group presented the greatest mean, and the 90-s group presented the greatest variation. Findings allow suggesting that the longer stretching is sustained, the more muscle flexibility is improved.