In forefoot running, the calves are more engaged as shock absorbers because landing with a forefoot strike during running helps organize key mechanical parameters (i.e increased ankle plantarflexion and knee flexion) that prevents the calf from overstretching at touchdown. As a result, less impact is dispersed up the leg and overloads to the calf muscle can be avoided. Read more here on how heel strike running has the opposite effect which makes the calves more vulnerable to injury as compared with forefoot running.
