###Human: There is tightness on my calf during sprint after gastrocnemius injury. Why? ###Assistant: Hello. Usually, post any sprint or run which is done all of a sudden without reconsidering it as a regular activity there might be doms (delayed onset muscle soreness) and this stays for around 4 to 5 days of time. Post that, the pain reduces in its own without any kind of medication. For now, since the pain is dropped down, do regular exercise which can help muscle stay in the active state so future pains are avoided due to doms and also do hot water fomentation for now for the calf muscle to relax.