How Sauna Bathing Boosts Endurance By Increasing Red Blood Cell Count

Saunas are broadly acknowledged as a useful tool for recovery among athletes. Stimulating heat shock proteins can reduce levels of inflammation, improve sleep quality and help repair muscle tissue.

The evidence that exposing the body to such extreme heat can actually enhance performance in endurance sport is less well known, despite it being one of the most appealing benefits. 

Here, Built for Athletes takes a look at how sauna bathing can increase endurance by stimulating red blood cell production.

 Saunas Can Improve 5k Time By 1.9%

 A small study in New Zealand looked at the effects of sauna bathing on six competitive male distance runners.

The athletes sat in a sauna for 30 minutes immediately following training sessions over a period of three weeks. 

They completed a run to exhaustion on a treadmill at their current best 5k pace at the end of the three weeks, as well as at the end of a three week period of normal training with no sauna bathing.

The time to exhaustion was an impressive 32 per cent greater after the sauna period, which equated to a 1.9 per cent increase in 5k running performance. 

Interestingly, the researchers also measured blood plasma and red blood cell levels and found they increased by 7.1 per cent and 3.5 per cent respectively.

Production Of EPO

The above study might leave you wondering how sauna bathing can lead to such an increase in red blood cells.

It’s thought to all be linked to sweat. The liquid that we sweat while sat in the sauna comes from blood plasma, and as our blood plasma levels become depleted and we dehydrate, the kidneys secrete a hormone called Erythropoietin (EPO).

You may have heard of EPO through doping scandals in endurance sports like cycling, but it’s a naturally occurring hormone that many athletes try to stimulate in more acceptable ways, such as training at high altitudes. 

EPO stimulates the production of red blood cells, so sauna bathing could be a natural and accessible way that athletes of any ability can improve their endurance outside of training.