I sometimes see people use the sauna before their workout. It often happens in winter when people get cold walking from their car to their gym through the freezing wind and icy snow on the ground. Maybe you do that too. By the time I relax into the cedar wood of the hot sauna, I have either finished my workout or did not exercise that day. It’s better to sauna bathe after working out. I only see two main scenarios for using the sauna before exercise.
The main reason for using the sauna pre-workout is to warm up your body prior to exercise. While sauna use prior to exercise should not take the place of foam rolling and mobility, it has similar cardiovascular effects as exercise. The heat from the sauna raises your core body temperature. To keep you cool, your heart rate will rise. Your blood volume increases. More glucose is delivered to your muscles. This will allow for greater muscle mobility. Mobility or light body weight movements can be easier after the sauna because your body is warm and muscles more mobile.
An athlete training may use the sauna before exercise for a specific use case in heat or with heat exhaustion. These are elite athletes who know what they are doing. An example is someone testing their VO2 max on an exercise bike after using the sauna to prepare for a race in a hot climate. Or a weight lifter may want to do super slow dumbbell bench press, at a lighter weight, in order to train their muscle when exhausted. With that said, these are elite performers who are training for a specific reason. I have not heard of one athlete who frequently trains after a true sauna session.
If you use the sauna before exercising, stick to mobility, bodyweight, or slow training. Your loose, flexible muscles post-sauna are not conducive to explosive lifts. I would not try squat as much weight as possible after your 30 minute sauna. Spending too much time in the sauna will have diminishing returns because your body has to use your energy to keep you cool. You want as much energy and focus as possible during exercise. A sauna session will drain you of that as your body’s heat response works to keep you cool. Have you ever tried playing a sport after hot yoga? You feel like a wet noodle. That is not conducive to athletic performance.
The best time to use the sauna comes post exercise. Recovery is a big reason why athletes use the sauna after exercise. Muscles recover while getting the cardiovascular benefits from the heat stress. You don’t have to be an athlete. Any person will benefit from using the sauna. The benefits include increased endurance, muscle strength, and the cognitive benefits. I only see two main use cases for using the sauna before a workout. It is much more optimal to use the sauna post exercise. If you have another use case that I did not mention, I’d love to hear from you!