Why do I get shin splints?July 2, 2014
Shin splints is a common term used to describe lower leg pain that occurs below the knee either on the front of the shin or along the inside of the shin. The technical term for this pain is medial tibial stress syndrome (MTSS), which is an overuse or repetitive stress injury of the shin.
The current thinking is that MTSS is a result of overloading the main bone in the shin, called the tibia. With weight-bearing activities the tibial bone bends slightly, straining the bone and causing micro-damage to it. This results in increased activity of bone cells to keep the bone strong and resist bending. At a certain point, the bone cells can no longer keep up with the damage being done and you start to see a decrease in bone density.
In addition to bone changes, evidence suggests that dysfunction of the muscles surrounding the tibia due to the repetitive stress also contributes to the shin pain. Weak and fatigued muscles are not able to absorb the shock from running as well as strong rested muscles, and therefore added stress is then placed on the bone. The stress on the tibia and its surrounding muscles occurs when the body is no longer able to heal properly in response to repetitive muscle contractions and tibial strain.
Improper walking and running patterns can also contribute to MTSS by increasing the stress applied to the muscles and bone of the shin. One major error in running mechanics commonly seen in people with MTSS is called overpronation. When we walk and run, pronation happens naturally as we shift our weight over the inside arch of our foot. This helps the foot absorb the shock of hitting the ground. However, without proper support to that arch, it is possible to overpronate which places excessive pressure over that arch causing it to flatten. This added pressure then pulls on the muscles that attach on the foot and travel up the shin. This puts extra strain on the bone because, as stated above, overworked muscles cannot absorb the shock from running as well as strong, rested muscles.
Who is at risk?
This pain is commonly seen in both runners and military personnel. In runners specifically, training errors tend to be a major factor in developing MTSS. Beginners often do not build their running mileage gradually enough and get pain as a result of doing too much too fast. The same pain can result in more experienced runners who abruptly change their workout regime, suddenly increasing their mileage, intensity, pace, or terrain. Individuals with previous injuries or those that run greater than 20 miles a week are even more at risk of developing an overuse injury, which is most often seen in runners but also in other ballistic sports such as football, basketball, soccer, and dancing.
There also appears to be a gender bias, as females are 1.5-3.5 times more likely to develop a stress fracture from MTSS. This higher risk is due to the higher incidence of diminished bone density and osteoporosis in women. This is often described by the “female athlete triad” which states that female athletes are more likely to experience osteoporosis, amenorrhea, which is the absence of a female’s menstrual cycle, and an eating disorder. These three conditions all affect and contribute to each other. These athletes are commonly energy deficient due to an imbalance between the amount of calories consumed and the amount of calories burned during exercise. This is the primary cause of the female athlete triad, as low calcium levels contribute to decreased bone density and make these athletes more vulnerable to stress fractures.
Signs and Symptoms
Early on, pain is worse at the beginning of exercise, gradually subsides throughout the training session and is relieved by rest. However, as the injury progresses, pain is present with less intense activity and may even occur at rest. There may also be some mild swelling and tenderness along the inner part of the lower leg.
How to Treat MTSS
Rest is a major factor in treating MTSS. The bone and muscles need a chance to heal themselves without the repetitive stress that running places on them. Avoiding activities that cause shin pain, swelling, or discomfort is important. However, you don’t need to stop exercising altogether. Low-impact exercise, like swimming or biking, is a great way to get a cardiovascular workout without placing too much stress on the shins. Ice can also be used to ease the shin pain, as ice helps to fight the inflammation that can form with tissue damage. Ice should be applied 15-20 minutes at a time, multiple times throughout the day.
If rest and ice do not help reduce the symptoms of MTSS, physical therapy is a good next step in treating the pain. Proper running mechanics may be a factor in the shin pain and a physical therapist can help correct the abnormalities in your running pattern. As previously discussed, overpronation can contribute to symptoms of MTSS. This occurs once your foot has already contacted the ground and as you move your body weight over your foot. However, there is also discussion that the way in which your foot initially strikes the ground may affect shin pain. The ideal foot strike is landing on the middle of your foot, referred to as the midfoot. However, individuals that experience pain with running often land on their toes, or forefoot, or back on their heels, the rearfoot. Midfoot striking is the best way to ensure that shock absorption is equally distributed throughout the foot without causing increased symptoms of MTSS.
Proper footwear is another important aspect of preventing and treating MTSS. A firmer shoe made to control pronation of the foot is ideal. Your shoes should allow your feet to absorb the shock of running without sending the stress elsewhere creating more problems in your body. Insoles could also be placed inside your shoes to help absorb some of the shock that running can place on your legs. Also, for runners sneakers should be replaced every 350-500 miles to ensure that the soles are still providing adequate support for the foot.
For any additional information on shin pain, please contact Total Performance Physical Therapy to schedule an appointment.