Many fitness hacks sound promising, but can actually be really hard to do right. You can work out for less time if you use high-intensity interval training, but you need to push yourself as hard as you physically can. Or there's the idea that exposing yourself to extreme environments may be a third pillar of fitness, but that can involve a plunge into an icy pool. Not so fun.
Those looking for an easier recommendation can take heart in a new finding. It turns out that an hour-long hot bath (or, presumably, a dip in some hot springs) can boost metabolic health and cause an anti-inflammatory response similar to exercise.
"Many cultures swear by the benefits of a hot bath," writes Steve Faulkner, lead author of the study, in The Conversation. "But only recently has science began to understand how passive heating (as opposed to getting hot and sweaty from exercise) improves health."
For the study, the researchers recruited 14 men and assigned them to either an hour of moderate cycling or an hour-long soak in a 104-degree bath. (Because the group was small and all-male, the results still need to be validated with larger studies involving both men and women, but this is a starting point.)
Unsurprisingly, the cyclists burned more calories, but bathers still burned about 140 calories on average — about what they would have used on a half-hour walk. More interestingly, the researchers measured blood sugar for the study participants for the next 24 hours and found the two groups both had improved ability to control blood sugar, an important measure of metabolic health.
In fact, the bathers' peak blood sugar levels after eating were about 10% lower than the peak blood sugar for the cyclists, which shows promise for using "passive heating" as a means of helping control metabolic disorders like type 2 diabetes.
The bathers also experienced an anti-inflammatory response similar to the effect seen in people after they exercise, which is also promising, since people with chronic disease tend to have chronic inflammation.
The researchers think the key here could be proteins that help regulate blood sugar — known as heat shock proteins (HSPs). HSP levels tend to be lower in people with type 2 diabetes, and these levels tend to rise after both exercise and "passive heating."
It's also possible that exposing your body to heat has similar effects to cold exposure — an activation of the circulatory system that may have long-term health benefits.
This is still early stage research, but the authors write that soaking in hot water might be helpful for people who could use the health benefits of exercise but struggle to follow a fitness regimen.
Of course, the results should not be seen as a reason to stop exercising and just take a bath instead. But if you're looking for an excuse to take a soak, go ahead and do it for your health.