75 athletes with a grade II strain of the hamstrings, quadriceps, or gastrocnemius muscles were randomized to a rehabilitation program with or without the addition of a platelet-rich plasma injection. The time to return to sport, pain intensity and rate of recurrence were assessed. Results demonstrated a statistically significantly shorter time to return to sport in the PRP group compared to the control group by approximately 4 days. Pain severity scores were lower in the PRP group throughout the study. There were no differences in recurrence rate observed between the two groups.