Running has become more popular since the increase of track and endurance racing has increased. It’s estimated that there are 30 million runners in the United States of America. Of those runners, 10 million run more than 100 days per year, and 1 million enter competitive races per year1. It‘s easy to see why running has become more popular in the past decade. Some benefits include potential weight loss, improved cardiovascular health, increased muscle mass, increased bone density, and an improved emotional state2.
As the amount of runners have increased in recent years, so has the occurrence of
running related injuries. Running injury severe enough to reduce or stop training or cause a runner to seek medical care is 37% - 50% of runners each year. These are the stages of a running injury1:
 Pain upon exertion
 Pain at rest
 Pain that interferes with activities of daily living
 Pain that is managed with medication
 Pain that is crippling.

Injury patterns are fairly constant over the past 25 years, despite better education, training and shoe design. There are over 20 types of running injuries including plantar faciitis, shin splints, Achilles tendonitis, runner’s knee, and iliotibial band syndrome. Most are caused by training errors and can be corrected. Of the most common running injury sites, 70% to 80% occur from the knee and below. The knee is the most common site of injury accounting for approximately 25% to 33% of running-related problems2.
There are multiple potential risk factors for getting a running injury. Risk factors
can be separated into intrinsic and extrinsic factors. Intrinsic factors include flexibility,
prior injury, misalignment, and poor form. Extrinsic factors include training errors ( I.e.
velocity, frequency, duration), improper running surface, and improper running shoes3. Two of the most important risk factors of a running injury include: number of miles each week, and previous running injury.
Most running injuries are musculoskeletal repetitive overuse injuries. Running is a complex and coordinated process that involves the entire body. Running causes many stresses in the body, because of the increased weight bearing on joint surfaces, kinetic chain influences, and altered biomechanics compared to walking. When the body is biomechanically inefficient, running causes repetitive stress on tendons, ligaments, muscles and joints. Weight-bearing stresses, compression, shear, torsion, overuse of muscles and tendons lead to an inflammatory response. Joint effusion and swelling cause pain, restriction of movement and decrease in function.
In order to properly return to the functional outcome of running, rehabilitation of running athletes must be staged with clear intent and goals for each stage of recovery.
Stages of rehabilitation (recovery):

Stage one: Self management, rest and restore range of motion
This acute stage includes temporary/relative rest from running to prevent further damage. PRICE (protection, rest, ice, compression, and elevation) is implemented and full range of motion of the injured structure is regained. Since the inflammatory response occurs only in the acute stage, modalities should only be focused in the initial stages of rehabilitation. The use of cryotherapy in the management of acute soft tissue injury is largely based on anecdotal evidence. Preliminary evidence suggests that intermittent cryotherapy applications are most effective at reducing tissue temperature to optimal therapeutic levels. However, its efficacy in treating injured human subjects is not yet known4. After the acute stage of injury, there is no significant effect in terms of function, swelling, or pain at rest. The application of ice after injury is accepted clinical practice even if the strength of evidence supporting the use of cryotherapy in management of acute soft tissue injury is generally poor4. Although there is a need for modalities for acute inflammation, you must treat the cause of the musculoskeletal injury by treating the tissue specific impairments.

Stage two: Fix muscle imbalance and work on body awareness
Although every individual is different, there are common muscle imbalances seen in regular runners. A muscle imbalance is related to two changes in muscle function: 1) a tightening of a mobilizing muscle, and a 2) weakening of a stabilizing muscle3. Mobilizing muscles are those that produce movement. They are often big muscle groups with that produce high power. Muscles that are usually tight and need to be stretched include: hamstrings, gastroc/soleus, quadriceps, hip flexors, hip abductors, pectoralis and anterior shoulder girdle. In contrast, stabilizer muscles control movement or joint position, often working against gravity. They are smaller and deeper muscles. Muscles that are commonly weak and need to be strengthened include: gluteals, hip abductors, VMO, hip adductors, tibialis anterior, trunk stabilizers, posterior shoulder girdle, and scapular stabilizers. Postural or biomechanical factors such as foot/leg alignment can also contribute to muscle imbalances and compensatory mechanisms. These impairments need to be addressed to improve running performance and prevent injury. For example, the hip abductors are commonly weak and can cause the entire leg pronate at the knee ankle and foot. This can be a contributing factor in anterior knee pain, patellar tendonitis, plantar faciitis, posterior tibialis tendonitis, and ITB friction syndrome6.

Stage three: Functional strengthening,
Over the past 10 years, isokinetics has become the exercise modality of choice for
rehabilitation the lower extremity. However, a review of literature indicates that closed
kinetic chain exercises have advantages over open kinetic chain exercises. A closed kinetic chain is a chain in which both ends of the chain are significantly constrained in the manner in which they are permitted to move. The distal aspect of extremity is fixed to an object that is stationary or moving in a running posture5. Examples of a closed kinetic chain exercise are variations of squats and lunges. Because of the relative position of the body during activity, closed-kinetic-chained exercises allow a more functional pattern of movement in regards to running. It provides multi-planar isometric, concentric, and eccentric contractions. Closed kinetic chain rehabilitation is shown to decrease shear forces, increase proprioception and increase muscle group coordination through examples of progressive exercises5. Open kinetic chain rehabilitation does not duplicate pronation forces that occur in close kinetic chain exercises and produces shear forces at the knee. Closed chain maneuvers can be used to compensate for inadequacies at a weak link in the chain. Quantifiable girth and peak torque don’t relate to functional ability. A significant feature of closed kinetic chain rehabilitation is the optimal development of proprioceptors. Rehabilitation should focus on re-educating proprioceptors to recreate functional movements in running/athletic performance. When an area is injured and rested or immobilized, both muscle and proprioceptors “forget” their role in controlling lower extremity acceleration and deceleration, with resulting lack of function, regardless of girth. Studies show closed kinetic chain rehabilitation is economical, efficient and effective means of rehab with the ultimate goal of enhancing proprioception, thus gaining lower extremity joint stability5. Developing proprioception and incorporating intrinsic timing with muscle force are essential for accurately performed functional activity.

Stage four: Efficient return to running
Plyometric exercises are specialized, high intensity training techniques used to develop athletic power (strength and speed). Plyometric training involves high intensity, explosive eccentic-concentric muscle shortening that invoke the stretch reflex (stretching the muscle before it contracts to create a greater force)6. The most common plyometric exercises include hops, jumps, and bounding movements. Plyometrics help with efficiency, improve power in running muscles, and increase reactivity of the nervous system. Studies show eccentric exercises are good for joint and soft tissue injury for endurance racing. Endurance running is associated with eccentric muscle fatigue, especially the hamstrings. Eccentric muscle fatigue may be a potential risk factor for knee and soft tissue injuries during running6. Eccentric muscle training should therefore be introduced as an integral part of the training program for runners.


Conclusion:
Most running injuries are musculoskeletal overuse injuries, and since physical therapists are the musculoskeletal experts, we are in a prime position to treat them. Modalities tend to be overused (i.e. E-stimulation, ice pack, ultrasound and electrical
stimulation ) and rehabilitation becomes mainly palliative. Medication and modalities can never treat the cause of a running injury, only the signs and symptoms. Running injuries must be geared toward the functional outcome of going back to running. The cause of the musculoskeletal repetitive stress injury must fixed by treating the tissue specific impairments, such as muscle imbalance, joint hyper/hypo mobility, and inefficient biomechanics. Rehabilitation should focus on functional activities that mimic running such as closed kinetic chained exercises and Plyometrics/eccentric exercises that increase running efficiency. As musculoskeletal experts, we must strive to return patients to functional ability. Physical therapy should be handcrafted for individual functional needs.

Bruce R. Wilk, PT, OCS, and Sokunthea Nau, DPT are physical therapists and Bernardo Valero is a physical therapy aide at Orthopedic Rehabilitation Specialists in Miami, Florida.

1. O Conner, Wilde. Textbook of Running Medicine. McGraw-Hill Professional Publishing May 30, 2001
2. Andrews JR, Harrelson GL. Physical Rehabilitation of the Injured Athlete. Philadelphia PA: WB Saunders CO: 1991: 1775-176.
3. Adrian MJ, Cooper JM. The biomechanics of Human Movement Indianapolis, Ind; Benchmark Press; 1989: 362-363
4. Tidball JG. Inflammatory cell response to acute muscle injury. Med Sci Sports Exerc. 1995; 27: 1022-32.
5. Blackburn JR, Morrissey MC. The relationship between open and closed kinetic chain strength of the lower limb and jumping performances. J Orhopedic Sports Physical Therapy. 1998; 27:430-435.
6. Tippet SR, Voight ML. Functional Progression for Sports Rehabilitation. Champaign, IL: Human Kinetics; 1995:43.