Tight calf muscles may be caused by biomechanical problems of the foot or even your running style can increase the strain on the calf muscles. Physio or Chiro practitioners can identify if you have these problems by performing a gait analysis on a treadmill to identify the issues and then prescribe stretches or specific exercises to correct this.
Calf muscles may have gradually tightened up over a period of months through not stretching enough before and after training. Tiny micro tears in the muscles cause them to go into spasm. When they are in spasm or contracted then blood cannot easily get into them. The muscles have squeezed the blood out like a sponge. If the muscles do not get enough blood then they will not get enough nutrients and so will tighten up to protect themselves and weaken and so on.
We have access to some great physio’s in the building, both Tim and Ryan from Hunter Performance Physio can assist you as can Garry from Hunter Healthy Spines if you are having troubles with calf tightening or cramping.