Muscle injuries (strains) are a common injury among both inactive and active people. These injuries can become recurrent and lead to significant losses in function and sport participation. Research has previously shown injections such as PRP (platelet rich plasma) are costly and ineffective to treat these muscular injuries. Conversely, these injuries require Physical Therapy and early, progressive loading of the injured tissue to both promote healing and re establish its' pre injury tensile strength. The main question remaining is how soon Physical Therapy should be started after an acute injury.
A recent study in the New England Journal of Medicine conducted a randomized controlled trial of 50 amateur athletes who sustained either a thigh or calf muscle strain (Bayer et al. 2017). Athletes completed the same rehabilitation program but were randomized to either early Physical Therapy (2 days) or delayed Physical Therapy (9 days after injury). The rehabilitation program consisted of 1 week of frequent stretching followed by 2-4 weeks of daily, progressive loading of the injured tissue. The final phases of the Physical Therapy rehabilitation program consisted of dynamic loading with increased resistance 3 days a week and finally completed the return to sport phase in weeks 9-12 consisting of functional exercises and heavy strength training 3 days per week.
As expected, the authors showed a 25% faster return to sport in the early vs. delayed Physical Therapy group (62.5 vs. 83 days). Importantly, the authors showed no increase in risk of injury among the athletes who completed the early vs. late rehabilitation programs. Authors reported this study supports the importance of early loading compared to immobilization of injured tissue. Previous research has shown immobilization impairs connective tissue cells and their ability to heal and return to pre injury composition. Authors stated the "importance of regular and controlled mechanical loading early after trauma" to facilitate an optimal return to activity.