It sounds like you have a case of medial tibial stress syndrome, commonly known as shin splints. This is a frequent problem with runners, especially those new to running or those who have had a long break from the sport.
The cause may be one or more of several things, including tight calf muscles, overpronation (excessive rolling in) of the feet, poorly fitted or old, worn out shoes, or being over-enthusiastic about training and doing too much too soon. Running on hard surfaces or doing a lot of hill work can also contribute to the problem.
If the pain is severe, you need to take a break from training for at least a few days and apply ice to your shins regularly to help reduce inflammation. A visit to a sports physio would probably be a good idea too.
Once your legs have recovered, there are a few things you can do to minimise the chances of shin splints recurring:
- Warm up thoroughly before running - a good 10 minutes of walking, then ease into the run.
- Don't increase distances too quickly or suddenly add a lot of hill work to the training schedule. Gradual build up is the way to go. The usual recommendation is to increase total weekly kms by no more than 10% each week.
- Apply ice to the shins after running.
- See a podiatrist - faulty biomechanics may be contributing to the problem, and orthotics might be required.
- STRETCH....especially the calf muscles, both the Gastrocnemius and soleus. Warm up, stretch gently, then run, then stretch again afterwards. Every time.
- Run on softer surfaces – try to avoid concrete and go for gravel or grass or a proper athletic running track.
- Work on strengthening your shin muscles – ask a trainer or physiotherapist for some appropriate exercises.
If the problem returns, you again need to rest and apply ice regularly. Pushing through will only make things worse.