issue 223

October 2025

As winter sets in, Ray Klerck dives into the research proving that the sauna isn’t just for cutting weight. It’s the seasonal weapon fighters need to stay healthy, recover faster, and keep their edge when cold weather and burnout hit hardest.

With the November temperature drops, it’s a time when almost everything is stacked against you. Cold weather. Travel. Clocks changing. End-of-year burnout. And none of this helps when everyone around is coughing up lung butter, which is made worse if you realize that as many as 78% of people who are exposed to the cold virus become infected. However, your risk of getting sicker becomes more pronounced as the shorter days weaken your defenses and increase your vulnerability to microbial infections. That can completely destroy your training consistency, but the good news is that daily wellness habits can make a significant difference to a fighter, especially when a sauna is involved. This kind of heat doesn’t need a prescription and is your frontline defense for almost every ailment a fighter needs. The sauna shouldn’t be something reserved for weight cuts or hangover detoxes. Instead, it should be an everyday addition to your recovery protocol, helping you transition smoothly from one fight to the next. 

BATTLING THE FRONT LINES

You don’t have to wear an overenthusiastic sparing session to land up flat on your back. Sometimes, all it takes is a dojo sneeze, that’s on the hunt for a nice health set of warmed-up lungs to colonize. If you’re the kind of savage who rounds off training with a sit-down in 200°F, then your immune system is already half a round ahead. Despite its dry-heat-rep, the sauna air actually hydrates the mucus lining in your airways, which can act like flypaper for viruses, clearing and trapping the invaders before they set up shop to create that dreaded autumn cough. It's one of the reasons why research in the American Journal of Medicine found that sauna helps shore up your airways and keep you healthy, even linking sauna use to half as many colds as non-users. What’s more, when people took roughly three Finnish sauna sessions each week, they had a lower risk of respiratory infections. Doing four sauna sessions per week reduces these risks by 41% compared to once-per-week users. Why does this matter? Well, gyms are ultra-communal. Sweat. Spit. Scabs. So, while the rest of your team is coughing up sound effects from a plague movie, the sauna can give your lungs the equivalent of a high-heat training camp.

HEAT YOUR SYSTEM, TRAIN YOUR CELLS

Heat shock proteins are the kinds of things you hear about on a Rogan podcast, but for a fighter, they’re the body’s backstage crew that fixes the damage from your training. The main character is HSP70, which is your cellular cut man that patches up battered proteins, stabilizes your muscle structures, and keeps all your internal machinery together. In a Finnish sauna study, HSP70 levels shot up sharply after the first session, then rose less dramatically by the tenth. Your body is learning the ropes, adapting to the stress, but that means that even if you sauna intermittently, then you’ll get that big immune boost. Sure, over time, your system learns to thrive under pressure like a veteran fighter, but that can be a good thing. It shows that the heat isn’t a biohacking recovery gimmick. It’s stress training at a microscopic level that prepares your body to fight off whatever you throw at it. 

THE SWELLING

Tempers. Knees. Egos. MMA is all about the inflame game. Every sprawl, strike, and nose jab adds another log to the internal fire. For fighters, inflammation is life. One study examined MMA fighters after a simulated fight, and their inflammation markers shot up. One called IL-6 shot up by more than 6,000%, another, IL-1β, climbed over 4,000%, and TNF-α, a significant trigger of inflammation, rose by 63%. Meanwhile, IL-10, the signal that normally cools things down, crashed by 98%. A more damning report card you will not receive, and this low-level fire can make your recovery slower each day. Fortunately, a Finnish study that tracked over 2,000 men who suffered from chronic inflammation found that those who used the sauna 4-7 times per week had 30% lower inflammation levels than those who used it once a week, even after accounting for diet, body fat, and fitness. Think of this as the sauna's reset button, so your body can conserve its energy for when it needs to fight. 

MOOD PROTECTION

As the daylight starts to shrink, sometimes your training spark can go with it. Less sunlight can mean lower levels of serotonin, the hormone that keeps your mood steady, and less vitamin D, which amplifies your energy levels. There is a hormonal relief associated with the sauna, where individuals who used it reported feeling better mentally, emotionally, and physically. Everyone who took part reported a deep sense of relaxation, psychological well-being, and relief from stress. Many described feelings of complete calm and joy, which is much the same as a post-fight high or endorphin rush, you’d expect after a solid training session. They went on to say it might be able to lift mild depression, reduce anxiety, and even restore appetite. The key to these adaptations might be your sleep hygiene. As many as 83.5% of people who regularly kick back in the sauna report better sleep for one to two nights after using a sauna, according to a paper in Complementary Therapies in Medicine. Better sleep can lead to improved moods, increased energy, and a more effective ability to manage stress. So, when daylight is in short supply and your moods start slipping into a slump, the sauna becomes more than a sweat box; it’s light therapy minus the light.

THE PERFORMANCE EDGE

It’s not all about recovery; there may be a possibility that the sauna warms up your performance from the inside out. Athletes who stretched in the same 8 weeks improved their hamstring and lower-back flexibility by a tidy little 83% compared to those stretching at room temperature. Heat turns stiff muscles and tight connective tissue into something more pliable, letting you sink deeper into each position and hold it longer without pain biting back. That can mean looser hips, freer movement, and fewer strings pulled tight in places you don’t want tightness. Flexibility is one upside, but when distance runners spent 30 minutes in the sauna after training, three times per week for three weeks, they seemed to get fitter. Their endurance improved by 2% and their run-to-exhaustion time increased by 32%. Those are performance leaps they’d usually need weeks of extra mileage to earn. It's believed the heat boosted blood plasma volume, allowing their muscles to get more oxygen. And in the colder months, this is how you keep your muscles moving while the rest of the gym is still thawing out. 

THE FIGHTER PROTOCOL

If you’re going to the sauna, do it like a pro. All the above research points to a series of sweet spots that blend recovery and performance. Start with 3 sessions per week, building to 4–7 sessions once you’re accustomed to the heat. Each session should reach a temperature of around 174–194°F (80–90°C), which is hot enough to make you question your life choices, but not your heart rate. If you’re chasing the immune and inflammation benefits, follow the Finnish model: three 15-minute rounds, separated by 2-minute cool-downs (a cold shower or a quick plunge works best). That’s the format that raised heat-shock proteins, improved immune readiness, and dropped inflammation markers by around 30% in people who used the sauna regularly. If you’re chasing endurance gains, deploy your session after training, as the runners did with a 30-minute sauna session, three times a week for three weeks. Flexibility freaks can keep it simpler by doing after your workout by spending 10–15 minutes in the sauna, stretching each major muscle group for 30–60 seconds. The eight-week study, which boosted flexibility by 83%, employed consistent post-session stretching with no gimmicks, relying solely on heat, breath, and time. Make sure you take care of your hydration needs before you get in there, add electrolytes, and avoid going in when you’re depleted. Treat the sauna like another round of training, not a shortcut. Done right, it’ll keep your lungs clearer and your body primed for whatever comes next.

THE HOT ROUND

The best part is that you don’t need a fancy cedar cabin or an influencer-grade sweat lodge to cash in on the benefits. A new study from the University of Oregon found that a hot tub or bath might even outperform a sauna in specific ways. When people soaked in hot water, their core body temperature rose higher, their blood vessels opened, and their immune response kicked in harder than with dry or infrared saunas. This works because water traps heat far better than air, so your body can’t cool itself by sweating. It raises your heart rate, increases blood flow, and activates immune cells, everything the sauna does. So, if you’re on the road, in a hotel, or just short on space, a bathtub or spa filled with 104°F water can do the job. Aim for 20–30 minutes per session, three to four times a week, and treat it like training for your circulation. You can do all of this without dropping ten grand on a custom unit or building a Finnish shrine in your backyard. The point isn’t the room, it’s the heat. Whether it’s a sauna, hot tub, or glorified bath, what matters is the rise in temperature and consistency. Heat the body, calm the system, and your cells won’t care how it happened. They’ll just know they’re ready for the next fight.