In amongst everything from blisters and chafing to plantar fasciitis and IT band syndrome, there’s one injury that puts fear into the heart of runners: the stress fracture. A painful injury that strikes seemingly out of nowhere, a stress fracture is guaranteed to keep you away from the start line.

However, learn the ins and outs of them, and you can set yourself up to avoid fractures and hit your goals with confidence.

What is a stress fracture?

Stress fractures are a relatively common overuse injury and over 80% of them occur in the legs of those affected.

They occur when muscles become fatigued and are unable to absorb added shock. Eventually, the fatigued muscle transfers the overload of stress to the bone causing a tiny crack called a stress fracture.

What are the general risk factors for stress fractures?

Stress fractures are generally a result of doing too much, too soon, without the body having enough time to adapt.

Biological factors such as poor limb biomechanics, low levels of fitness and irregular periods in women can also pose a risk.

It’s also thought that running form can have an impact on the likelihood of stress fractures in some cases. There does seem to be a link to tibial stress fractures with those who overstride with a definite heel strike. This type of running style also increases load at the hip, increasing the possibility of femoral stress fractures.

Steady on before you make a snap decision to switch to a forefoot strike, though. Running with a forefoot strike increases the load on the foot and ankle, which can increase the risk of stress fractures in the foot. Making the change to more minimal footwear or to a forefoot strike too quickly can increase the risk of a metatarsal stress fracture.

Insufficient nutrition can also put you at risk. Research reported that low levels of vitamin D may increase the risk of stress fractures, and suggested that active individuals may need high levels of it than the general population.

Low levels of calcium can also put runners at risk, along with a high caffeine intake, too much sodium in the diet and generally not eating enough to offset activity levels.

What are the symptoms of a stress fracture?

Keep an eye out for pain during running that gets worse as you go, a sharp pain you can pinpoint on a bony area, and pain while resting. A problem that comes on suddenly is a real red light, so if you’ve had no symptoms and rapidly acquire a pain that prevents you from moving normally, it’s time to take action.

The most common running related stress fractures are to the tibia. This is followed by fractures to the metatarsals (small bones of the foot), fibula and femur. Stress fractures can also occur in the pelvis of runners, although this is much less common.

So, an abrupt, pinpointable pain in your foot, shin, thigh or pelvis is not one to try and run through.

How do you treat a stress fracture?

Once diagnosed by a doctor, who’ll use an X-ray, CT, MRI or DEXA scan to suss out the injury, a splint may be used to support the bone as it heals. Pain can be treated using painkillers such as paracetamol and by icing the affected area.

The most important treatment is rest. Individuals need to have a complete rest from the activity that caused the stress fracture, and engage in a pain-free activity during the six to eight weeks it takes most stress fractures to heal.

If running is resumed too soon, larger fractures can develop which can lead to chronic problems in the bone.

It can take anything from a few months to longer for a fracture to fully heal. In the meantime, low impact exercise such as cycling and swimming can be taken, as long as your doctor considers you ready and you take on the extra activity gradually.

Having a gait assessment from an experienced physio as you begin running again can help pin down any biomechanical issues that could put you at risk of re-injury.

How can I avoid stress fractures?

Make all changes gradually. Advanced planning for any training programme is a great way to prevent stress fractures. Set yourself a mini 4-6 week pre-training programme involving very gradual increase in mileage.

When participating in any new sports activity, set incremental goals. For example, do not immediately set out to run five miles a day; instead, gradually build up your mileage on a weekly basis.

Varying the surface that you run on can also help to prevent stress fractures, as can substituting a ‘recovery run’ session with cross training such as swimming or cycling. Most importantly, when planning a training programme, be realistic with your distance and speed targets.

Diet also plays a major role in avoiding stress fractures.