Sauna after your workout, not before — it cut systolic blood pressure 8.0 mmHg in a 2022 RCT

The answer is after — and the data is clear

Do the workout first. Then the sauna.

That's not a preference — it's what the research supports. A 2022 randomized controlled trial — people randomly split into groups and compared — found that participants who added a 15-minute post-exercise sauna session to their workout showed greater improvements in cardiorespiratory fitness and a clinically meaningful drop in systolic blood pressure (–8.0 mmHg) compared to people who just exercised alone (Lee et al., 2022).

Going into the sauna before your workout blunts the training effect. Here's why that matters — and what the timing actually does to your body.

Post-exercise sauna cut systolic blood pressure by 8.0 mmHg — exercise alone didn't.

— Lee et al. (2022). Effects of regular sauna bathing in conjunction with exercise on cardiovascular function. Am J Physiol Regul Integr Comp Physiol.

What sauna actually does to your cardiovascular system

Sauna heat raises your core temperature, which forces your heart to pump harder to move blood to the skin surface. That elevated blood flow is the key stimulus.

A review in the European Journal of Applied Physiology explains the mechanism directly: repeated exposure to elevated blood flow — whether from exercise or heat — trains the inner lining of your blood vessels (the endothelium — the thin layer of cells that controls vessel dilation and contraction) to work more efficiently (Weaver et al., 2022). Sauna and exercise tap into overlapping pathways here.

That's why combining them can deliver more than either one alone. But the order determines whether the two effects compound — or cancel each other out.

Heat therapy and exercise drive vascular adaptation through the same pathway: elevated blood flow to the endothelium.

— Weaver et al. (2022). Non-pharmacological interventions for vascular health and the role of the endothelium. Eur J Appl Physiol.

Why sauna before the workout is the wrong order

A sauna session raises your heart rate, drops your blood pressure, and reduces plasma volume — the fluid portion of your blood. When you then try to lift or sprint, your body is already partially depleted before you've done a single set.

Rissanen et al. (2020) measured what happens hemodynamically — meaning blood pressure, heart rate, and fluid levels — across four different exercise-plus-sauna protocols. Plasma volume dropped significantly during every exercise session, and sauna further accelerated that drop. Starting with the sauna means you're already behind on fluid before your workout begins.

Lower plasma volume = less blood delivered to working muscles = worse performance.

You haven't warmed up. You've pre-fatigued yourself.

What the RCT actually showed about post-workout sauna

The Lee et al. (2022) trial ran 8 weeks with 47 sedentary adults who had at least one cardiovascular risk factor. Three groups: exercise only, exercise plus post-workout sauna, or a control group.

The exercise-only group improved cardiorespiratory fitness (how efficiently your body uses oxygen during effort) by +6.2 mL/kg/min. The exercise-plus-sauna group improved by +2.7 mL/kg/min — but also dropped systolic blood pressure by 8.0 mmHg and lowered total cholesterol, outcomes the exercise-only group didn't achieve.

Different adaptations, not the same ones. The sauna wasn't replacing the training benefit — it was adding a cardiovascular layer on top.

One note worth making: the sauna group's fitness gain was smaller than the exercise-only group's. That may reflect the extra cardiovascular load of the sauna reducing the pure training intensity participants could sustain. More reason to treat post-workout sauna as a recovery and vascular tool — not a performance booster.

What about testosterone — does sauna timing matter there?

You may have seen claims that sauna kills your testosterone. A 2026 review in Sports Health looked specifically at legal strategies athletes use to optimize testosterone — and found something clear: sauna bathing appears to be neutral on testosterone (Lazarev et al., 2026). Cold-water immersion may actually lower testosterone, but the sauna doesn't.

So if you're doing a hot-cold contrast after training — sauna then cold plunge — that's a different question. But a standard post-workout sauna session won't interfere with the hormonal signal your training just created.

The same review confirms that sleep quality is the most critical factor for testosterone secretion, since it's tied to the REM phase — the deep, restorative stage of sleep. A post-workout sauna, by lowering core temperature over the following hour (your body overshoots after reheating), may actually support the sleep quality that protects testosterone overnight.

Sauna bathing appears to be neutral on testosterone — cold-water immersion is the one that may lower it.

— Lazarev et al. (2026). Testosterone-Optimizing Strategies in Athletes. Sports Health.

How long and how hot: the practical protocol

The Lee et al. (2022) RCT used 15 minutes post-exercise at Finnish sauna temperatures (typically 80–100°C / 176–212°F). That's the dosage that produced the 8.0 mmHg blood pressure drop.

Rissanen et al. (2020) measured responses across endurance, strength, and combined training — all followed by sauna. Key practical findings:

- Endurance exercise + sauna produced the biggest blood pressure reductions: –8.9 mmHg systolic immediately after, –11.0 mmHg at 30 minutes post.
- Strength training + sauna also showed positive effects, though slightly smaller than the endurance pairing.
- Plasma volume — the fluid in your blood — increased significantly the next day in groups that combined endurance training with sauna. That's a meaningful recovery signal.

What to do after your session:

1. Cool down for 5–10 minutes before entering the sauna — let heart rate come below 100 bpm.
2. Hydrate before you go in. You've already lost fluid training.
3. 15 minutes is enough. You're not chasing more heat — you're letting the recovery mechanism run.
4. Shower cool (not ice cold) after. This helps core temperature normalize, which supports sleep onset.

And if you're training primarily for cardiovascular health, the combination of cardio before or after weights order decisions and a post-workout sauna gives you two compounding vascular stimuli on the same session.