Strengthening tendons and ligaments. Usually pitchers who throw slow have weak tendons and ligaments which leads to injury so strenthen those
This is from a site i was browsing on.
"However, to develop strength in the tendons and ligaments, which will lead to increased strength in subsequent work-outs and ultimately greater muscle gains, the idea is to execute these movements over a shorter range of motion. "
Meaning when you lift…For developed pitchers only, Workout with your max but instead of say doing a full bench press, do it half way so the tendons and ligaments take the work and load and build up.