Can Adding Sauna Supercharge Your Workouts?

This Week’s Research Highlight

You wrap up a tough workout — lungs burning, sweat dripping, heart pounding in your chest. You’ve challenged your muscles, strengthened your heart, and taken another step toward better health, maybe even a longer life.

But what if you could get even more from that same training session — without adding any exercise?

Sauna bathing has long been a staple of recovery routines, but its effects may be sorely underappreciated. A single sauna session mimics key aspects of exercise, raising heart rate and blood pressure before triggering a deep, post-session drop — just like aerobic training.

That raises an intriguing question: If sauna mimics aspects of exercise, does adding it to a training program amplify cardiovascular effects? Or does exercise alone already max out these benefits, leaving little room for sauna to add much extra?

To answer this question, researchers in Finland (the place where saunas originated) put post-workout sauna to the test in a randomized controlled trial.

The results? More impressive than even the researchers anticipated.

Inside the Study

Finnish researchers designed a multi-arm randomized controlled trial, testing whether adding sauna sessions to an exercise program would enhance the benefits of exercise alone.

They recruited 47 inactive adults and randomly assigned them to one of three groups:

• Exercise Only: Engaged in a structured 8-week training program.

• Exercise + Sauna: Followed the same exercise program but concluded each session with a 15-minute sauna at increasing temperatures.

• Control: No intervention; maintained usual lifestyle

The exercise protocol was identical for both active groups: three 60-minute sessions per week, including 20 minutes of resistance training and 30 minutes of cycling at increasing intensities.

Before and after the 8-week intervention, researchers analyzed several key cardiovascular markers, including:

• Cardiorespiratory fitness (VO₂max)

• Blood pressure

• Total cholesterol

By layering sauna on top of exercise, the researchers weren’t just comparing two separate health interventions — they were testing whether sauna use could amplify the physiological adaptations that make exercise so beneficial.

Confirming Known Benefits of Physical Activity

Let’s start by looking at exercise alone vs. no exercise.

It’s not exactly a secret that regular physical activity improves health, and this study reaffirmed those well-documented benefits. After eight weeks, participants in the exercise-only group saw clear improvements in both cardiorespiratory fitness (VO₂max) and body composition compared to those who remained sedentary:

• VO₂max increased by 2.6 mL/kg/min — a 9% improvement from baseline.

• The control group, on the other hand, actually lost fitness over the same period, exhibiting the toll of inactivity.

• Participants in the exercise group also lost fat and increased lean muscle mass, reinforcing the well-established metabolic benefits of regular training.

But exercise alone had limits.

Despite better fitness and improved body composition, blood pressure remained unchanged, and cholesterol levels didn’t budge.

So, if exercise alone wasn’t enough to improve cardiovascular markers, could stacking sauna on top of training drive additional physiological adaptations?

The answer turned out to be yes — and what’s more, it didn’t just influence those biomarkers. It also augmented the fitness gains from exercise itself.

Boosting Fitness Gains

The sauna group didn’t merely outperform the exercise-only group — they nearly doubled their fitness improvements.

Starting with a baseline VO₂max of 26.4 mL/kg/min, participants improved to 32.0 mL/kg/min, or an absolute increase of 5.6 mL/kg/min. This translates to a 21% boost in cardiovascular fitness.

This improvement was enough to move many participants into a higher fitness category, shifting them from "poor" to "fair" — a transition linked to substantial reductions in cardiovascular disease risk.

But the impact doesn’t stop there. Large-scale research has shown that every 3.5 mL/kg/min (~1 MET) increase in VO₂max reduces all-cause mortality risk by 10-15%. Given their 5.6 mL/kg/min improvement, participants in the sauna group would be expected to have a 15-30% lower risk of premature death.

This level of improvement typically requires months of structured endurance training; yet here, it was achieved in just eight weeks simply by adding a 15-minute sauna session post-workout.

How Heat Triggers a Cardiovascular Boost

Why did sauna bathing nearly double the fitness gains from exercise alone? One of the most powerful explanations lies in plasma volume expansion — a key cardiovascular adaptation that improves endurance by increasing blood volume.

When exposed to heat, the body expands plasma volume to defend against dehydration. Sweat is drawn from blood plasma — the liquid portion of blood — so the body compensates by producing more plasma, effectively boosting circulation and oxygen delivery.

But here’s where it gets interesting: this isn’t just a temporary response. With repeated exposure, the body adapts by maintaining higher plasma levels long-term, mimicking an effect seen in elite endurance training.

This has been captured in carefully controlled studies. In one trial, trained cyclists who added post-workout sauna sessions increased their peak plasma volume by 17% in just four sessions. And this can produce substantial improvements in performance: male distance runners who used sauna post-workout improved time to exhaustion by 32% in just three weeks, which was correlated to increased plasma volume.

The findings from the exercise + sauna group in this study fit right in with these endurance studies: sauna exposure appears to accelerate cardiovascular adaptations, enhancing VO₂max beyond what exercise alone can achieve.

The cardiovascular advantages of sauna use didn’t stop at VO₂max. While plasma volume expansion likely explains the supercharged fitness gains, it may not be the full story. One of the most striking findings from this study was how sauna exposure also lowered blood pressure — something exercise alone failed to do.

The Overlooked Benefit: Blood Pressure Lowering

The sauna + exercise group saw a significant drop in systolic blood pressure, decreasing from 134 mmHg to 126 mmHg — an 8 mmHg reduction in just eight weeks.

For many, this shift moved them out of the "elevated" or "stage 1 hypertension" category and closer to normal levels. That’s clinically meaningful. Research shows that just a 5 mmHg drop in systolic blood pressure correlates with a ~10% lower risk of heart attack and stroke, suggesting that this reduction could have a real impact on long-term heart health.

Meanwhile, the exercise-only group saw no change (134 mmHg before and after). Same workouts, different results — implying that heat exposure provided a cardiovascular benefit that exercise alone did not.

The question is, why? That’s where heat’s impact on vascular function comes in.

The Power of Vasodilation

Why did sauna + exercise significantly lower blood pressure while exercise alone didn’t? The answer lies in how heat alters circulation and vascular resistance.

Sauna exposure triggers a powerful vasodilation response, causing blood vessels to widen and increase blood flow to the skin for cooling. This reduces vascular resistance, making it easier for the heart to pump blood and naturally lowering blood pressure — a process similar to what happens during aerobic exercise.

Heat also enhances the production of nitric oxide (NO), a key signaling molecule that helps arteries relax and remain flexible. By increasing NO bioavailability, sauna use keeps blood vessels open longer, helping to sustain the blood pressure-lowering effect well beyond the sauna session.

From Patrick & Johnson, 2021

This phenomenon has been repeatedly demonstrated in studies. In one experiment, a single 30-minute sauna session lowered systolic blood pressure by an average of 7 mmHg, with effects persisting even after recovery. And the long-term benefits are even more compelling. A 25-year prospective cohort study found that men who took saunas 4-7 times per week had a 47% lower risk of developing hypertension.

These findings suggest that heat exposure may play a unique role in improving circulation and lowering blood pressure — benefits that exercise alone didn’t provide in this study.

Sauna’s Surprising Impact on Cholesterol

The benefits didn’t stop at blood pressure. Sauna use also improved cholesterol. Over the eight-week intervention, total cholesterol dropped from 200 mg/dL to 188 mg/dL in the sauna + exercise group—a 12 mg/dL (6%) decrease. Meanwhile, the exercise-only group saw a slight increase (203 mg/dL to 208 mg/dL), and the control group showed minimal change.

A 12 mg/dL reduction in just eight weeks doesn’t sound like much but it is clinically meaningful, particularly for those with borderline elevated cholesterol. Similar improvements are often achieved with dietary interventions, such as supplementing soluble fiber.

So what’s driving this change? The answer may lie at the cellular level, where heat activates protective molecules that influence how the body processes lipids.

Heat Shock Proteins: The Body’s Built-In Repair Crew

When cells are exposed to stress, they activate heat shock proteins (HSPs). Think of HSPs as the cell’s emergency response team, rushing in to repair and protect proteins before they lose their form.

Why does this matter? Proteins are the workhorses of the body, but their function depends entirely on keeping the right shape. Heat, as well as other stressors, can destabilize proteins (think about how an egg white solidifies when fried). Fortunately, your cells have a built-in defense: HSPs act as molecular chaperones, helping misfolded proteins regain their structure and stay functional.

Heat is a powerful trigger for HSP activation. Just one sauna session can boost HSP levels by 49%. But even better, repeated sauna exposure trains the body to produce more HSPs over time, improving stress resilience.

Heat shock proteins — good for more than just cholesterol regulation!

From Patrick & Johnson, 2021

Okay, so what does this have to do with cholesterol?

Well, HSPs do more than repair proteins — they help regulate cholesterol metabolism by assisting in cholesterol transport and clearance from cells. This may explain why sauna use improved cholesterol levels in this study, while exercise alone did not.

In short, sauna exposure acts as a controlled stressor that strengthens the body at the molecular level, enhancing cardiovascular health in ways exercise alone may not.

From Short-Term Gains to Long-Term Health

The benefits seen in this study — improved fitness, lower blood pressure, and better cholesterol levels — aren’t just numbers on a chart. They align with real-world outcomes linked to longevity.

A 26-year prospective study of 2,277 middle-aged men found that those with high cardiorespiratory fitness had a 50% lower risk of cardiovascular death compared to those who were less fit. But those who combined high fitness with frequent sauna use (3-7 times per week) saw an even greater 58% risk reduction — suggesting sauna amplifies the long-term benefits of exercise. And this effect remained strong even after adjusting for traditional cardiovascular risk factors.

The takeaway? Sauna isn’t just a recovery tool — it’s a simple but powerful way to enhance cardiovascular resilience.

For those already exercising, adding a short post-workout sauna session may be an effortless way to maximize results. And for those just getting started, sauna use may help accelerate adaptations, making your workouts feel easier and more effective.

Summary: Finnish researchers investigated whether adding sauna to an exercise routine could amplify cardiovascular benefits. After eight weeks, participants who combined exercise with post-workout sauna sessions saw nearly double the improvement in cardiorespiratory fitness compared to exercise alone. They also experienced an 8 mmHg reduction in systolic blood pressure and a 12 mg/dL drop in total cholesterol — benefits that exercise alone failed to produce. The findings suggest that heat exposure enhances cardiovascular adaptations, making workouts more effective and potentially lowering long-term disease risk.

Random Trivia & Weird News

🍔  A Burger King in Helsinki had a sauna installed.

In Finland, saunas aren’t merely common — they’re a way of life. With roughly one sauna for every three people, they’re found in homes, offices, and even the Finnish Parliament. But in 2016, a Helsinki Burger King took things to the next level, opening the world’s first fast food sauna.

This wasn’t just a gimmick. The 15-person sauna featured blue and red benches (matching Burger King’s colors), along with a shower room, locker room, and media lounge complete with a TV and gaming consoles. Guests could wrap themselves in Burger King-branded towels while ordering a Whopper directly from the sauna.

Because in Finland, no place is complete without a sauna — even a fast food chain.

Podcasts We Loved This Week

• Christopher Gardner: What should the Dietary Guidelines say? Via Sigma Nutrition Radio.

• Sarah Amend: What does an animal’s size have to do with its cancer risk? Via Science Friday.

Products We Like

Venture Pal Electrolyte Drink Mix

When it comes to athletic performance, sodium is the most important electrolyte, not just for replacing what you sweat out, but for maintaining blood plasma volume. More blood volume means improved oxygen delivery to your hard working muscles, better heat dissipation during exercise, and reduced cardiovascular strain during intense efforts.

(This is even more crucial, of course, if you’re combining exercise with extended heat exposure.)

But the problem is that most electrolyte drinks don’t contain nearly enough sodium to truly support hydration during prolonged sweating. That’s why I am a fan of Venture Pal — each packet delivers 1,000 mg of sodium, enough to actually replenish what’s lost.

It comes in four mild flavors designed to balance out the saltiness. I’m partial to watermelon, but I’d recommend trying the variety pack to find your favorite.

humanOS Catalog Feature of the Week

The How-to Guide to Ergogenic Aids

We’ve talked about how sauna amplifies the benefits of exercise, but what about other science-backed tools to enhance performance?

Ergogenic aids — from nitrates and caffeine to beta-alanine and creatine — can help boost endurance, strength, and recovery when used strategically.

But not all supplements deliver real benefits, and some may even interfere with training adaptations if used incorrectly.

This Guide breaks down:

• What actually works (and what doesn’t)

• Who benefits most from each supplement

• How to use them effectively

If you’re looking to train harder, recover faster, or maximize adaptations, check out the full guide!

To Access:

1. Login to humanOS
2. Click How-to Guides on the left-hand side
3. Click Ergogenic Aids (first row, on the right)

Also, you can search “ergogenic aids” in the search field after you’ve logged in:

Wishing you the best,