Does decreased muscle strength cause acute muscle strain injury in sport? A systematic review of the evidence

Abstract

Sport injury prevention is becoming an essential element in providing physiotherapy services to an active population, both at the recreational and elite levels of sport. Prior to developing prevention strategies for injury it is important to establish modifiable risk factors for injury. Acute muscle strain injury is one of the most common injuries seen in sport, however, there is relatively little known about prevention of this injury. These injuries often recur and can become chronic. The cause of acute muscle strain injury in sport has been attributed to: improper warm-up, poor flexibility, overuse, muscle weakness, muscle imbalance, and fatigue by many authors. Most of the evidence to support these potential causal factors, however, appears to be based on animal studies and anecdotal evidence. The purpose of this systematic review of the literature is to determine if decreased muscle strength is a cause of acute muscle strain injury in sport. This review is based on observational epidemiological evidence in which the exposure measure is an objective measurement of muscle strength or an intervention including a specific strengthening programme, the outcome measure is an acute muscle strain injury and an attempt has been made to create a comparison group. There were no clinical trials published addressing this issue. Most studies reported some association between decreased muscle strength and acute hamstring strain injury in sport. Most studies had limitations regarding internal validity. All studies had limitations precluding applicability to a wider athlete population. Despite an apparent association between decreased muscle strength and specific hamstring strain injury in elite male athletes in sport, the evidence for decreased muscle strength as a risk factor for or cause of muscle strain injury in sport is inconclusive. Further research is required to confirm this relationship.