A Cochrane review included 3 studies with a total of 124 subjects. Two small trials compared times to return to normal function, and definition of this outcome varied between studies. The first trial, involving 80 athletes, suggested stretching four times a day instead of just once and resulted in a statistically significant reduction in time to return to normal function (mean difference (MD) -1.8 days, 95% confidence interval (CI) -2.15 to -1.45, P < 0.001). The second trial, with 24 participants from a diverse sporting background, found that progressive agility and trunk stabilization exercises and icing did not achieve a statistically significant reduction in time to return to full function when compared to stretching and progressive resistance exercises and icing (MD -14.5 days, 95% CI -30.64 to 1.64, P = 0.08). The third trial, conducted with 20 non-athletes, suggests there was no evidence of effect with manual therapy on soft tissue length (MD 10.4 degrees, 95% CI -3.19 to 23.99 in favour of manual therapy, P = 0.13), on hamstring muscle peak torque (MD -0.7 foot-pounds, 95% CI -18.45 to 17.05 in favour of control, P = 0.94), or on quadriceps femoris muscle peak torque (MD -22.1 foot-pounds, 95% CI -59.00 to 14.80 in favour of control, P = 0.24) following a single treatment.
Comment: The quality of evidence is downgraded by the study quality and heterogeneity.