Don't shy away from using the gym sauna. Regular use of the sauna, Jacuzzi, or hot tub may improve your workout performance. Here's what intermittent heat can do.
Exposure to heat can increase the amount of heat shock proteins (HSPs). These are specialized proteins which are protective and regenerative in nature. In particular, HSPs can deliver the following effects:
Muscle adaptation is an essential part of training progression. If a muscle group is unable to adapt to the stressors being placed upon it, it won't grow stronger or bigger.
During exercise, especially resistance training, HSPs are transiently elevated to facilitate the "chaperoning" of amino acids to the site of muscle damage to initiate recovery. Accumulation of amino acids to the local site of injury isn't merely sufficient for repair, as correct protein folding needs to occur as well. HSPs ensure the correct assembly of these amino acids into the appropriate protein, ultimately enhancing hypertrophy.
Now, don't go and subject yourself to marathon sauna sessions. Quick visits ranging from about 15-30 minutes are optimal. This practice is known as "intermittent hyperthermia" and it's been shown in studies to enhance growth of skeletal muscle.
The eccentric, the negative or lowering portion of a lift, is the most promising range for muscular growth, but many people just drop the bar without actively resisting the weight. In a study, intense eccentric exercise was able to boost HSPs by over 1000 percent, clearly showing how the muscular damage that occurred during the rep must've been massive. Followed up with intermittent hyperthermia, the way would be paved for muscle growth.
So, heat acclimation makes your body function better, both aerobically and anaerobically, as well as in removal of toxins. Coupled with the potential for increased muscle gains, sauna time should be a no-brainer.