Shin splints and stress fractures are common injuries among athletes, especially endurance athletes. But how do you know which one you're suffering with? Here we explain the differences between the two, plus how to prevent and treat them.

　　Shin splints vs stress fractures: what's the difference?

　　A shin splint or medial tibial stress syndrome (MTSS) is an inflammation of the tissue running along the shin bone (tibia), whereas a stress fracture is a very small crack or group of cracks that form in the bone itself.

　　What are shin splints?

　　Shin splints can occur when the layer of connective tissue that covers the surface of the shin bone (periosteum) becomes inflamed or irritated.

　　With a shin splint, if you run your fingers over the shin, it’ll usually hurt all along the bone. Many people describe it as a diffuse, dull ache along the inner border of the shin (tibia).

　　It’s normally worse after running or weight-bearing activity and some triathletes will report feeling the same type of pain when out of the saddle on the bike. But if you ignore the pain it can become sharp and acute, limiting your ability to train.

　　What causes shin splints?

　　Shin pain is often difficult to treat as there are so many factors that contribute to the pain, making every individual’s diagnosis and treatment plan slightly different.

　　If you’re experiencing ongoing/worsening shin pain, the most important thing to do is consult a physiotherapist to rule out more serious problems, like stress fractures or compartment syndrome.

　　Risk factors:

　　Poor conditioning/muscular endurance around the shin and lower limb.

　　Excessive range and speed of foot pronation.

　　Alteration in training, suddenly increasing distance, pace, terrain.

　　Incorrect footwear.

　　Poor muscle function around the hip and knee, overloading the shin.

　　As shin pain is normally associated with impact, your swimming and cycling training should be pain-free and therefore fine to continue as normal. If painful, you can easily reduce the load by taking out the push-off-the-wall when swimming and staying in the saddle during your rides.

　　How can you treat shin splints?

　　First, look at your training programme and make sure any changes in your run are done with a gradual build (volume and pace).

　　Make sure your run shoes work for you. Training shoes should be replaced regularly to ensure they’re not wearing down and that the sole remains effective at absorbing and returning force.

　　If your shin pain is ongoing, it may be useful to see a podiatrist who will assess the biomechanics around your feet and may design you some insoles to help control any movements that are putting extra stresses through the shin.

　　As mentioned, poor conditioning of the lower limb can be a factor, so below I’ve outlined exercises you can undertake to condition all the muscles that have an effect on the shin mechanics.

　　The first four exercises will build not only strength, but the endurance of these muscles, essential for 5km and 10km running. It’s advised to do all four exercises to fatigue/failure.

　　The exercises are technique-based and you should do as many as possible up to 3 x 25 reps, but stop if technique fails. Don’t worry if you can only manage half to start with. Build up slowly, running them all every day if you already suffer from shin splints.

　　Complete the two final stretching exercises immediately after, and do as much as you think necessary for your specific needs.

　　Exercises to improve lower limb conditioning

　　Straight leg calf raises

　　Muscle targeted: Gastrocnemius

　　Method: Stand with both feet on a step, with your heels just hanging off the edge. Keep legs straight. Rise up onto the tiptoes of your left leg first (stand next to a wall to help maintain balance if needed), hold for a few seconds then slowly lower. Try to use the full range of the muscle and keep the foot in a neutral alignment. Aim for 3 x 25reps on each leg.

　　Bent leg calf raise

　　Muscle targeted: Soleus

　　Method: As above, but instead of going up on tiptoes, bend down at the knee. This exercise will primarily work the soleus, the postural muscle of the calf, which is important for endurance running and control around the ankle when running. Aim for 3 x 25reps on 
each leg.

　　Foot raise

　　Muscle targeted: Tibialis anterior

　　Method: Stand on both feet, facing against a wall/solid structure to hold onto. Pull the toes and forefoot up to work the muscle in the front of the shin. Aim for 3 x 25reps.

　　Pronation control

　　Muscle targeted: Tibialis posterior

　　Method: Start by standing on a step on your right leg, with your big toe and arch resting at the edge. Slowly control your foot as you let 
the arch of your foot drop down to meet the step.

　　Work the tibialis posterior by pulling the 
arch of the foot back up into position. The strengthening of this muscle is important to help control of pronation of the foot while running. Aim for 3 x 25reps on each leg.

　　Calf stretch

　　Muscle targeted: Gastroc and soleus

　　Method: Stand with one leg in front of the other, with both feet pointed forward, leaning against a solid structure. Keep the back leg straight, with the heel pressed into the floor, feel the stretch before bending the back knee.

　　The straight back leg stretches the gastroc; the bent back leg stretches the soleus. Hold each movement until you feel the stretch release off slightly, which can be anything between 20secs to 1min, depending on the individual.

　　Repeat on the other leg.

　　Calf foam roller

　　Muscle targeted: Gastroc and soleus

　　Method: Sit with the roller under your calf, stacking one foot on top of the other. Support your body weight with your hands and roll the length of the calf, altering the angle of the leg to get the outside and inside of the muscle.

　　It might be too difficult to keep your bum off the floor, or you may find you need this pressure for the exercise to be effective. Do for 3mins minimum but, as above, until you feel the tightness easing off.

　　What is a stress fracture?

　　A stress fracture is a partial fracture (or break) of the bone that usually only goes a little way through. There’s usually one specific ‘spot’ or multiple spots that hurt really badly. If you have a stress fracture, you’ll also experience pain when walking and sitting.

　　Stress fractures are an overuse injury, where the bone is unable to withstand a repetitive mechanical loading. This is different from a full fracture or break of the bone caused by a sudden traumatic mechanical stress.

　　In triathlon, most injuries are in the lower limbs and can be attributed to the running discipline. Commonly they occur in the tibia, fibula, metatarsals (small bones of the foot), navicular and femurs.

　　What causes stress fractures?

　　The most common precursor to a stress fracture is previous bone stress or an injury history of stress fractures. However, this is not the only cause. You’re more prone to stress fractures if you suddenly increase your volume of running or are new to the sport.

　　It can also be as a result of changes in the type of load (addition of speed sessions) and running terrain. If you’re unfortunate enough to have poor lower limb and foot biomechanics this can also lead to bone stress.

　　Finally, poor conditioning and lower limb strength can be a cause, as the stronger the muscles supporting the bone, the more force they can absorb and therefore the less is transferred to the bone.

　　There are other factors that can contribute to bone stress, too, including low vitamin D levels, poor dietary intake and irregular or a lack of a normal menstrual cycle in females. However, if you feel that these are an issue in your specific case, it’s important that you consult a doctor.

　　What are the signs and symptoms of stress fractures?

　　The signs and symptoms to look out for in the case of a stress fracture are as follows:

　　Pinpoint pain: this may be specific to the bone itself, which then radiates around the point.

　　Pain on mechanical loading: i.e pain when you run, get out of the saddle when you’re cycling or push off the wall in swimming. (At other times you may be completely pain-free.)

　　Persistent pain: pain persists after the aggravating activity. You might get an ache/pain at night, there may be a small area of swelling around the fracture site and the pain returns if you only rest it for up to a week.

　　How do you treat a stress fracture?

　　Your GP or physiotherapist will take a thorough look at your history and after a number of clinical tests will be able to diagnose a stress fracture. Although sometimes helpful, X-rays often won’t detect a stress fracture in the early stages. Your doctor can refer you for an imaging scan, CT or MRI to confirm their diagnosis.

　　Treatment is very much dependent on how early you identify the correct diagnosis, as well as the location of the injury.

　　Sadly, there’s no quick fix to a bone injury and most will need completely offloading and immobilising (in a boot, cast/splint or crutches) for up to six weeks to give them time to heal.

　　A gradual return to training follows, where the bone is progressively loaded back to your normal level. During this time it’s vital that you’re pain-free, but the majority of athletes will return to full fitness.