Two days after a brutal leg workout, when delayed muscle soreness is at its peak, you hobble back in the gym and do it all again, because you are a warrior. That’s admirable, but a study published in the Scandinavian Journal of Medicine & Science in Sports seems to indicate that it might not be doing your physique as much good as you think.
The Finnish researchers looked at the hormone levels of athletes after doing an unfamiliar exercise to failure and then again two days later after completing the same workout. Growth hormone levels were significantly lower after the second workout. (The subjects were also much weaker during the second session.)
If you train hard, make sure your hormone levels are optimized with enough sleep, calories, and recovery time. When you are really sore, don’t be afraid to take an active recovery day and do a hike, swim, bike ride, or some yoga.