Musculoskeletal injuries constitute the largest class of athletic injuries sustained in sports. Any injury that occurs to a skeletal muscle, tendon, ligament, joint, or a blood vessel that services skeletal muscle and any related tissues is a musculoskeletal injury. The musculoskeletal system is the structural movement-generating component of the body. The capacity for movement is closely allied to the relationship between the musculoskeletal and the neuro-muscular systems, which is the interconnection between muscular movement and its control through nervous system impulses.
Sport participation along with a healthy and active lifestyle involve an inherent risk of musculoskeletal injury. The majority of these injuries are resolved without significant long-term consequences (or sequelae in medical language). The usual short-term consequences of musculoskeletal injuries will include the following limitations to physical function, irrespective of the part of the anatomy to which the injury was sustained:
- Decreased physical strength: Muscular ability will begin to decline after 24 hours of inactivity.
- Nerve impulses slow: At optimal health, the nervous system can transmit some nerve impulses, such as those crucial to coordination and reaction, at speeds of over 300 ft (100 m) per second. Inactivity through injury will reduce the overall ability of the nervous system to stimulate movement.
- Circulation and metabolic rates will slow.
- Bone mineral density decreases: Injury tends to slow the rate at which calcium and vitamin D operate in union to produce new bone cells. Collagen, the cellular protein material that provides bone with the elasticity to absorb forces directed into the otherwise hard mineral surface, is not generated at pre-injury levels.
- Collagen level decreases in the connective tissues, primarily tendons and ligaments, making these structures stiffer, less elastic, less responsive to movement, and more vulnerable to injury.
- Reduced cardiorespiratory function: The ability of the body to process oxygen, described VO2max, will decline by a limited amount in the first few days of inactivity due to injury, with pronounced declines exceeding 10% of peak oxygen uptake after 15 days.
- Reduced glycogen storage: Both the musculoskeletal muscles and the liver, the primary storage sites within the body for glycogen, will not maintain peak storage levels absent muscular activity that places demands upon the body's ability to utilize glucose, converted from glycogen.
The most common cause of musculoskeletal injury is a combination of physical overloads created by overtraining or by the repetitive use of a joint or a particular muscle group. Virtually every sport has a potential for this type of injury; these injuries are more often caused by training routines than by the stresses of a single competition. Distance running is a sport that by its nature will often create conditions for both overtraining as well as leg and foot injuries that are attributable to the repetitive strains of the activity. The injuries sustained in running are rarely connected to a single event, unlike the injuries of many contact sports; running injuries commonly are a combination of the mileage covered by the athlete in a given training period, the pace with which the training distances are run, the nature of the terrain covered in training, as well as the unique physical characteristics of the athlete, such as structural deformities or imbalances and age. These overloads lead to micro fractures of the bone structure, muscle and tendon tears, and ischemia, the reduction of blood supply to an organ or tissue. In a cross-sectional analysis of the frequency of injury occurrence among athletes of all ages and ability levels, the greatest number of musculoskeletal injuries occur to males between the ages of 15 and 25 years.
The distribution of the frequency of the different types of musculoskeletal injuries is relatively equal between male and female athletes, although different types of specific injuries occurred more frequently due to the physiological differences between men and women. The most striking of these examples is the far greater risk that female athletes face regarding a prospective anterior cruciate ligament knee injury, due to the relatively wider pelvis in relation to femur length in the female anatomy.
Various sport and government organizations in North America and Europe have analyzed musculoskeletal injury rates. Approximately 25% of all athletes will expect to sustain a musculoskeletal injury in a 12-month period. The more fit and the more sophisticated the athlete, the more likely the risk of injury, due in part to the fact that such injuries often occur to athletes performing at a higher level with greater physical stresses and risks.
The research on such injuries also confirms that foot and ankle injuries are the most common of musculoskeletal injuries, constituting approximately 25% of these occurrences. Knee injuries of all types are the next most common, representing 22% of musculoskeletal damage. Back injuries are the next most prominent occurrence, at 11%. Injuries to the lower leg, thigh, hip, shoulders, and the hand/forearm structure each occur at frequencies of between 5% and 10%.