by John Robert Cardillo Intense sun exposure is the stimulus that causes sunburn which results in a suntan, likewise hi-intensity training is the stimulus that causes muscle soreness which results in muscular growth. In the case of a sunburn, it takes several days of total rest away from the sun to allow the skin to recuperate and heal. As is the case after a hi-intensity workout session. Total rest and recuperation is the only way to ensure that the worked muscles have a chance to grow. The reward of hi-intensity training are “growth days”. Read More …