It's a question of heat. Prof. Lewis Halsey's research is unveiling the upper critical temperature (UCT) for humans - somewhere between 104°F and 122°F.

It's a question of heat. Prof. Lewis Halsey's research is unveiling the upper critical temperature (UCT) for humans - somewhere between 104°F and 122°F.

As the mercury rises, so does our resting metabolic rate. This intriguing correlation is at the heart of Halsey's team's studies at the University of Roehampton, UK.

As the mercury rises, so does our resting metabolic rate. This intriguing correlation is at the heart of Halsey's team's studies at the University of Roehampton, UK.

Animal species have preferences for temperatures, optimizing their energy expenditure. Strangely, information on humans' thermal neutral zone is scant - until now.

Animal species have preferences for temperatures, optimizing their energy expenditure. Strangely, information on humans' thermal neutral zone is scant - until now.

Knowing when our metabolic rates climb could influence various areas of life. From work conditions, sports, and medicine to international travel, the implications are vast.

Knowing when our metabolic rates climb could influence various areas of life. From work conditions, sports, and medicine to international travel, the implications are vast.

The team isn't stopping there, they're also probing how our hearts react to sweltering temperatures. Age and physical fitness seem to alter these effects - another puzzle to be solved.

The team isn't stopping there, they're also probing how our hearts react to sweltering temperatures. Age and physical fitness seem to alter these effects - another puzzle to be solved.

Their most surprising finding? Key differences in cardiovascular responses to heat between men and women. This is just one of many ways individual responses can vary.

Their most surprising finding? Key differences in cardiovascular responses to heat between men and women. This is just one of many ways individual responses can vary.

This detailed research isn't easy - high-tech echocardiographs are not meant for high temperatures. Yet, Halsey's team is pushing forward, determined to uncover our body's secrets.

This detailed research isn't easy - high-tech echocardiographs are not meant for high temperatures. Yet, Halsey's team is pushing forward, determined to uncover our body's secrets.

In a warming world, this research gains ever more significance. Understanding our body's response to heat stress is becoming crucial - it's our personal adaptation to a global challenge.

In a warming world, this research gains ever more significance. Understanding our body's response to heat stress is becoming crucial - it's our personal adaptation to a global challenge.