Yes, saunas help with sore muscles. The heat increases blood flow to fatigued tissue, triggers protective responses at the cellular level, and reduces the perception of pain. A 2023 study in Biology of Sport found that a post-exercise infrared sauna session cut muscle soreness roughly in half compared to passive rest, with participants reporting lower pain scores both immediately after the session and 14 hours later.
How Heat Reduces Muscle Soreness
When you sit in a sauna after exercise, your core temperature rises and blood vessels dilate. This sends more oxygen-rich blood to muscles that were just damaged during training, speeding the delivery of nutrients needed for repair while carrying away metabolic waste. That increased circulation is the most immediate mechanism behind the relief you feel.
But the benefits go deeper than blood flow. Heat stress causes your cells to produce protective molecules called heat shock proteins. These proteins act as molecular chaperones: they stabilize damaged proteins inside muscle fibers, prevent further breakdown, and help cells reassemble the structural components needed for repair. When heat shock protein levels are low, as they tend to be during periods of inactivity or aging, muscles lose regenerative capacity and are more prone to wasting. Sauna use reliably boosts their production.
Heat exposure also triggers a significant spike in growth hormone, which drives protein synthesis and helps shuttle amino acids into muscle cells. Research has documented up to a 16-fold increase in growth hormone following sauna sessions. While that spike is temporary, repeated sauna use after training may create a cumulative environment that supports muscle repair and growth over time.
What the Research Shows for DOMS
Delayed onset muscle soreness, the stiffness and tenderness that peaks 24 to 72 hours after a hard workout, is where sauna research gets most specific. In a controlled study comparing infrared sauna sessions to passive recovery after resistance training, participants who used the sauna reported soreness scores of 2.9 out of 10 at the 14-hour mark, while the passive recovery group scored 5.2. The sauna group also saw smaller increases in soreness from their baseline, rising by only 0.9 points on average compared to 2.1 points for those who simply rested.
Beyond pain scores, the sauna group maintained more of their explosive power. Their drop in countermovement jump performance (a standard test of lower-body power) was significantly smaller than the control group’s. That matters if you train frequently: less soreness and better preserved performance means you can return to quality training sooner.
Traditional vs. Infrared Saunas
Traditional Finnish saunas heat the air around you, typically to 150 to 195°F, and your body warms indirectly. Infrared saunas use light panels to heat your body directly without raising the room temperature as much, operating at roughly 110 to 140°F. Both types raise your core temperature and trigger the same cascade of increased blood flow, heat shock protein production, and hormonal responses.
Most of the controlled recovery studies have used infrared saunas, partly because the lower air temperature makes longer sessions more tolerable and easier to standardize in a lab setting. The Mayo Clinic notes that infrared saunas produce similar physiological results at lower ambient temperatures. If you only have access to a traditional sauna, you’re not at a disadvantage for muscle recovery. The key variable is getting your core temperature elevated, not the method of heating.
What About Lactic Acid?
A persistent claim is that saunas “flush out lactic acid,” but the reality is more nuanced. Your body clears blood lactate within about an hour of exercise regardless of what you do afterward. The sauna doesn’t meaningfully speed that process. What regular sauna use does appear to do is improve your body’s relationship with lactate over time. A study on trained middle-distance runners found that three weeks of post-exercise sauna bathing improved their running speed at the lactate threshold by about 4%, roughly 0.6 km/h faster than a control group. The likely explanation involves increased blood and plasma volume from heat acclimation, which improves circulation to organs responsible for clearing lactate and dilutes its concentration in the blood. So while a single sauna session won’t “detox” lactic acid, consistent use can make your body more efficient at handling it during future workouts.
How Long to Stay In
For post-workout recovery, 15 to 20 minutes is the recommended range. That’s generally enough time for your core temperature to reach about 101 to 102°F, the threshold where the beneficial heat stress responses kick in. Going beyond 20 minutes in a single session doesn’t add much benefit and increases the risk of dehydration or dizziness, especially after exercise when you’ve already lost fluids through sweat.
If you’re new to saunas, start with about five minutes and add a few minutes each session as your body adapts. Drink water before and after. The post-workout window is ideal because your muscles are already warm and blood flow is elevated, so the sauna amplifies a process your body has already started. You can also use a sauna on rest days for general recovery, though the effect on acute soreness is strongest when paired with the training session that caused it.
What Saunas Won’t Do
Saunas reduce the severity of soreness and help preserve performance between sessions, but they don’t replace the fundamentals. Sleep, adequate protein intake, and progressive training design still account for the vast majority of your recovery. A sauna won’t fix soreness caused by a training load your body isn’t prepared for, and it won’t accelerate the healing of an actual muscle strain or tear. Think of it as a tool that smooths the edges of normal post-exercise discomfort and may give you a slight advantage in readiness for your next session, not a substitute for rest when rest is what you need.