Injury

For some runners, and maybe many athletes of other sports, who train near the body limits in terms of volume and intensity, fighting injury is one of the major components of training. 

The best practical way for runners who do not have professionals, such as personal coaches or sports medicine doctors, to take care of them regularly to manage injury prevention and healing is to attain the necessary knowledge by themselves.  The book Lore of Running (Noakes, 1991) offers the foundation of this knowledge and it is always a good point to refer to first when dealing with injury.

There are three steps to deal with any injury:

1. Diagnosis.  Some common injuries ( such as shin splints,  ITB syndrome) are easy to identify. Bone injuries can be accurately diagnosed by X-ray or bone-scan.  Some muscle injuries are tricky to diagnose.  Sometimes the spot of pain involves multiple muscles.  It is hard to pinpoint a specific muscle responsible for the pain.  One intuitive way to narrow the suspects is to contract or stretch the suspected muscles individually.  You can do this by using apparatuses exercising different muscles in a health club, or going through some stretching exercises targeting at different individual muscles.  Anatomy of Movement by Blandine Calais-Germain is a very good book for finding out which muscle does what.  Lower Extremity Muscle Atlas is an excellent Web site that illustrates the the anatomy, functions of lower extremity muscles. 
2. Treatment.   In most cases, injuries are healed by the body's natural capability.  All we need to do is to help this process.  The first response of body to an injury is inflammation - increase of blood flow by the increase of blood vessels' calibers and opening more capillaries in the injured area, increased capillary permeability and leukocytic exudation.  The disappearance of  the pain caused by inflammation does not mean that the injury is completely healed.  There are two fundamental ways to help: 1. breaking scars produced by the healing process; 2. increasing the blood perfusion of the injured spot.  The body heals the torn tissue by letting the damaged cells die and grow new cells to replace them. This process creates scars (clusters of dead cells) that may take a long time for the body to absorb. The scars pose the threat of further injury by sticking to healthy cells and tearing them during movement. Increased blood perfusion will enhance the growth of healthy cells and speed up scar absorption.  Massage is believed to help both processes. Whether stretching prevents or helps heal injury is controversial. Intensive stretching injured muscle can often exacerbate the injury. Stretching surely enhances performance.  To the contrary of many people's belief, complete rest is rarely the best way to recover from any injury.  Some moderate exercise or training helps blood infusion and scar breakdown. Some Chinese liniments and medicated plasters are believed to help local blood infusion and scar elimination.  They have been used for at least over a thousand years.
3. Restoring strength.  As stated above, some light training is helpful for injury recovery.  It is essentially a kind of rehab.  The essence of light training during recovery is to exercise gently the injured tissue such as a particular muscle and gradually strengthen it to its original state.  The intensity of training is dependent on the recovery stage.  Training should never be so intensive that it causes sharp pain at the injury spot.  Some very light dull pain may be acceptable, but if the recovery does not progress for days, the intensity of training should be reduced immediately.  Racing almost always exacerbates injury. Racing during late stage of injury recovery may be acceptable, but the cost is delaying full recovery by a week or so, or even weeks if reinjury happens.  It is very dangerous to make a rigid training program based on speculated recovery progress.  Training plan, if there is any, should be reassessed every day based on how the body feels during training. Each training session should be subject to adjustment during training depending on how the injured spot responds.  Running form may also need to change to minimize the chance of worsening the injury.  Usually this kind of running form change happens naturally while the runner tries to avoid the discomfort caused by the injury spot.  One interesting note is that shortening stride length decreases the impact on the lower part of the leg during the ground pounding phase (Clarke TE, et al. 1985); lengthening stride length (with the same running speed) decreases the shock wave at the higher part of the leg, the hip and above (Derrick TR, et al. 1998).  Therefore stride length can be adjusted according to injury location.  

The best thing to do regarding injury is to prevent it from happening.   This is a difficult task for people who train to near the body limits.  This is especially true for those who also have limited time allocated for training.  This involves the following efforts:

1. Wearing proper shoes.  More than half of the population have biomechanical problems. For example, a lot of us have over-pronated feet, some have the opposite - over-supination. They need quite different types of shoes. For every runner, the cushioning of shoes is always very important. 
2. Knowing the body limits.  This requires years' experience in a specific sport. No one can tell exactly what the limits are.  It is always a trial and error process, the balance between risk and health. The body limits change with the condition or the age of the body.
3. Knowing the pre-injury symptoms.  This also requires years' experience (including experience of injuries).  Reduce training volume or intensity immediately when the symptoms occur.
4. Balancing the use of different muscles.  Different workouts utilize muscles differently.  Some workouts use some muscles maximally while others use these muscles to a less degree.  A mixture of speed workout, hill workout, long run, LSD, tempo run is a very healthy program.
5. Choosing the appropriate running surface.  The best running surface is probably flat dirt path that is neither too hard or too soft. Cambered surfaces cause one feet over-pronation, the other over-supination.  Very hard surfaces add extra stress on the muscles responsible for deceleration and stabilization. 
6. Auxiliary exercise.  Strength workouts are believed to help prevent injuries and enhance performance.  Strengthening the relatively weak muscles (such as the the hamstrings that are weaker than their antagonists - quadriceps) is especially important.  Stretching  has been controversial in terms of helping prevent injuries (Yeung EW and Yeung SS, 2001; Black JD, Stevens ED, 2001; Shrier I, 1999).  The most important thing to remember when stretching is that never mixing stretching and contracting for the same muscle at the same time; in other words, the posture for stretching should be such that the target muscle does not contract at all to maintain it.  Cross training such as swimming, biking is good for recovering from racing, injuries. It helps prevent injuries in the sense it replaces some workouts that may be over-training.
7. Balanced diet.  There is probably no such thing as injury prevention diet program, but a balanced diet with adequate hydration is always good for health, performance and injury prevention.

Another note about injury is that almost all injuries are caused by deceleration (or braking) process.  Acceleration rarely causes any injury.  Quadriceps are responsible for most accelerations in running.  They are seldom injured. The hamstrings that are responsible for decelerating the movement started by the quadriceps are probably the most frequently injured leg muscles. This is why uphill running rarely causes any injury because it demands extra work from quadriceps.  The downhill running is dangerous because it requires extra work from hamstrings to brake the extra extension of legs.  This is why Most muscle strains occur in the lower extremities with the rectus femoris and biceps femoris (one of hamstring muscles) muscle being most commonly affected; they are followed by the semitendinosus (one of hamstring muscles), adductors, vastus medialis and soleus ( Greco A, et al., 1991).

The following are notes about a few specific injuries:

• Hamstring injury
• Short External Rotator Muscles of Hip injury
• Gluteus maximus injury
• Chronicle muscle injury
• Delayed onset muscle soreness (DOM)
• GI problems.
• Hip injury
• Iliopsoas tendonitis (a type of groin pain)
  

References:

Black JD, Stevens ED.(2001) Passive stretching does not protect against acute contraction-induced injury in mouse EDL muscle.  Muscle Res Cell Motil. 22(4):301-10

Clarke TE, et al. (1985) The effect of varied stride rate upon shank deceleration in running. J Sports Sci.3(1):41-9

Derrick TR, et al. (1998) Energy absorption of impacts during running at various stride lengths. Med Sci Sports Exerc.  30(1):128-35

Greco A, et al. (1991) Spin-echo and STIR MR imaging of sports-related muscle injuries at 1.5T. J Comput Assist Tomogr 15:994-999.

Noakes, T (1991) Lore of Running. Leisure Press, Champaign, Illinois.

Shrier I (1999) Stretching before exercise does not reduce the risk of local muscle injury: a critical review of the clinical and basic science literature. Clin J Sport Med 9(4):221-7

Yeung EW and Yeung SS (2001). A systematic review of interventions to prevent lower limb soft tissue running injuries. Br J Sports Med. 35(6):383-9.