According to analysis, if you are a marathon runner aiming for a personal best, your body shape could be as crucial as your training. The study, which examined 170 Ironman competitors, revealed that taller and leggier runners tend to outperform others in warm weather, while shorter and stockier individuals have an advantage in colder temperatures.

However, the researchers noted that this effect is observed exclusively in men. They propose that natural selection may have favored faster men, making them superior hunters.

Professor Ryan Calsbeek, the author of the study and a professor of biological sciences at Dartmouth College, stated that his research is among the first to suggest that human physiology may have adapted to different climates to enhance physical performance.

“Global patterns of temperature and climate may have shaped human body types to look and perform the way they do,” he said.

Even before embarking on endurance events like Ironman triathlons and marathons, athletes may find that their body type and the temperature conditions play a significant role in their performance.

Similar to animals, humans exhibit adaptations to different climates. Cold-adapted species often possess stockier builds and shorter limbs to minimize heat loss, while sleeker physiques are advantageous in hotter climates for efficient cooling.

The research, published in the journal PLOS ONE, examined 171 triathletes who had participated in multiple Ironman events, with some taking place in hot locations and others in cold regions. Utilizing software, the study analyzed the athletes’ physique based on photos from these competitions.

Triathletes were chosen for the study due to the event’s suitability for investigating how the size and shape of the human body impact performance. In an Ironman, participants must complete a 3.8km swim (2.4 miles), cycle 180km, and run 42.2km.

“There is one event, running in particular, that we know to be important in the evolution of humans and two events – swimming and cycling – that are not,” Prof Calsbeek said, which made comparisons very useful.

He found the greatest difference in performance based on physique came in the running section.

Endurance athletes are urged to think about which climates their body shape and type might be naturally suited to, while not taking their eye off the ball on training and motivation either.

“People attempting a personal best time can think about race locations and average temperatures, to pick a venue based on how their body type is adapted to perform,” Prof Calsbeek said.