Tour Down Under Stage 3

Tour Down Under Stage 1

Tour Down Under Prolog

Warm Up

Pre Race 2

Heat training has recently become very popular in endurance sports. While previously used mainly as acclimatization before hot races, new studies have shown an increase in hemoglobin (Hb) mass, similar to altitude training, that should also help in climate conditions. What was missing until now was a sound understanding of the mechanism behind the increase in red blood cell mass.

This study is the first to summarize the current state of knowledge, even though clear evidence is still lacking.

The two main reasons for the increase in Hb mass after heat stress are
1. The kidney senses the lower (diluted) hematocrit after heat induced blood plasma (the fluid compartment of blood) expansion and increases EPO production (known as the critmeter theory).
2. Reduced oxygen availability in the kidneys during heat stress due to i) lower renal blood flow, as blood flow is diverted to the skin for cooling, and ii) increased oxygen utilization in the kidneys due to increased renal workload (mainly sodium reabsorption). Both lead to local hypoxia that triggers EPO production.

Another postulated mechanism is the stabilization of HIF (the main transcription factor that senses tissue hypoxia and subsequently upregulates EPO production) via heat shock proteins produced when body temperature is elevated.

A summary of the six studies that found increased Hb mass after prolonged heat training is shown in pic. 2. The increase in Hb mass was between 19 to 42 g, with each g of Hb mass corresponding to a ~4 ml/min increase in VO2max.

Top Sports

Anton Schiffer

Recovery and a new study on heat training

2 Photos

9 Comments

Segments

Sign up to view more activities from Anton Schiffer

Tour Down Under Stage 3

Tour Down Under Stage 1

Tour Down Under Prolog

Warm Up

Pre Race 2

Want to see more?

The #1 app for runners and cyclists

Sign Up for Free. Track your progress and reach goals. Join 100 million active people on Strava.

See More from Anton