An initial experiment had a subject doing 10 sets of pull ups to muscle failure with 3 min rests. The purpose was to raise body temperature to test the parameters for extracting heat from the hand. One day, after completing 10 sets and cooling at the conclusion of the workout, the subject went back to the bar and did the same number of pull-ups as in the first set --- the muscle fatigue was gone.
Upon discovering this, over the next 6 weeks (with 2 sessions/week) the subject cooled after the 10th set. Over that 6-week study the subject went from a total of 100 pull ups to 180 pull ups.
For the next 6 weeks the subject cooled after every other set during the 3 min rest (except for control days). The subject improved from 180 pull ups to 616 pull ups. The most significant gains were seen on cooling days, not control days. Gains were maintained throughout the study period, providing lasting performance benefits.