Long-distance running continues to attract new enthusiasts throughout the world, and its unique combination of benefits can help people to control their weight, improve cardiovascular function and fend off a host of chronic health problems. But for all these advantages, running is hard on some parts of the body and often leads to lower-extremity injuries. A running injury is a condition that causes an athlete to decrease his/her weekly training mileage, and typically happens because of repetitive microtrauma which injures the weakest anatomical location in a vulnerable structure. In fact, a summary of the research to date finds that 45%–70% of endurance athletes suffer from a running injury within any 12-month span. Recreational runners have it even worse: 90% of 200 recreational half-marathon runners experienced one or more running injuries within a 12-month training period. Importantly, novice runners have higher injury rates than experienced runners. Experienced runners tend to have less risk of injury because they develop an innate ability to recognize the onset of an injury and keep it from worsening.

What are the most common running injuries? Studies suggest knee-related injuries are the most common, accounting for 26%–50% of all lower-extremity injuries. The foot, ankle and lower leg have a combined occurrence rate up to 50%. The hip and low back are also vulnerable to running injuries.

What are the most common injury causes? Research identifies these common training errors that lead to running injuries:

• rapid increase in weekly mileage
• continuous high mileage. Runners averaging 50–70 miles per week have a 50% chance of injury; some research indicates that the risk begins to increase meaningfully at ≥40 miles per week.
• abrupt change in running surface
• failure to follow hard training days with light training days
• wearing inadequate or worn-out footwear
• running on uneven surfaces
• returning to previous mileage too fast after a layoff
• running 12 months without a break from training
• history of previous injuries
• too much hard interval training
• training for competition
• muscle imbalances near a lower-extremity joint and/or inadequate muscular strength or range of motion (O’Toole 1992)

When researching world-class runners, I was fascinated to learn that Kenyan runners do not run at all for 2 months of the year.  This provides their bodies with substantial downtime for recovery, and healing of any injuries that might have occured in the build up to big races.

In terms of treatment, the initial stage should begin with rest, ice and nonsteroidal anti-inflammatories (NSAIDs) to reduce inflammation. A decrease in inflammation improves the range of motion of an injured joint and speeds up the healing process.  NSAIDs also provide pain relief which enables rehabiltation exercises to be performed. Some authors say stretching has not been substantiated as a way to prevent injury; conversely, while others propose that stretching exercises may help develop appropriate ranges of motion to prevent scarring and shortening of the healing tissue after injury.

Those dealing with running injuries need to consult with a medical practitioner or therapist to choose the best rehabilitation strategy. In addition, it is also important to acknowledge that because people heal at different rates individuals should seek professional advice on the treatment plan that will best suit their bodies' needs. While recovering and rehabilitating, it is important for runners to stay fit by cross-training, which will provide the injury time to heal yet stave off losses in aerobic capacity.  As running is metabolically more demanding than almost any other exercise modality, some loss of aerbic capacity is expected - but it will be attenuated by cross training.  Examples to consider include running in water, swimming, biking and cross-country skiing. Critically, strengthening muscular deficiencies can improve the balance of forces around the injured joint, and eccentric training can help during the rehabilitation phase. Strengthening the hamstrings eccentrically after an overuse injury of the knee is one example.

In conclusion, it is paramount to schedule days off for recovery and avoid excessive downhill running on consecutive days, and it may help to regularly vary running direction on a track or road. My experience informs this assertion on an anecdotal level. In my own 20-year running career, I have found that truly taking days off to recover in a meaningful way, especially after hard workouts, has led to injury-free training (after enduring years of injuries, when I was younger), and faster times. For those of us who enjoy being fast, note that training adaptions to running - as with all exercise - occur during the recovery period, as opposed to during the actual exercise session.  With this in mind, take liberty to schedule rest days as part of the actual training program.