Calf pain while running is a common problem reported by runners of all ages and abilities. The repeated movements patterns of the running gait and energy transfers of between 8-12 times body weight, partly explains the stresses that running place on the calf and Achilles area.

For less experienced runners, calf pain can be caused by poor strength and conditioning of the muscles and often over enthusiasm to progress causing overload, resulting in pain and dysfunction.

More experienced runners will tend to have better conditioning inherently from running over many years (although not always). Problems can occur through subtle and undetected (by the runner) changes in running frequency, intensity, time and type (surface. hills etc). If you are experienced runner, think back to any changes in these components of training, usually up to six weeks prior to the onset of symptoms. 

Changes in running shoes, especially to more minimalist running shoes can also increase the load to this area, as it will encourage a more forefoot running style. If you have recently changed to a more minimalist shoe, make sure you strengthen the calf and soleus muscles to help the manage the increased forces at the ankle joint. You may get some relief from stretching the calf muscle, if you do, you will still need to strengthen the muscles to let the body adapt to the forces placed upon it.