Why short, stocky soccer players are going out of style

By Mark Waghorn via SWNS

The days of short, stocky soccer players like Lionel Messi are numbered - because of global warming, according to new research

Climate change is boosting taller, leaner athletes - such as Manchester City star Erling Haaland.

The findings are based on an analysis of nearly 200 Ironman contestants over two decades.

Performance - especially in endurance running — was linked to how their physique adapted to shedding or retaining heat.

Long-limbed runners excelled in hot weather - while those with stockier Wayne Rooney-style builds fared better in the cold.

It is the first study to suggest human physiology may be adapted to climate to optimize performance.

Lead author Professor Ryan Calsbeek, of Dartmouth College, said: "This study shows variation in running performance among male triathletes is consistent with both Bergmann's and Allen's rules.

"That suggests that global patterns of temperature and climate may have shaped human body types to look and perform the way they do.

"These patterns that determine differences in body shape among species around the planet may also influence performance in Ironman triathlons and other endurance sports."

Named for the 19th-century biologists Carl Bergmann and Joel Asaph Allen, the rules dictate that overall body size of animals — as well as the length and thickness of their limbs — correspond with climate.

Cold-adapted species tend to be burlier with thicker, shorter limbs to limit heat loss, while their sleeker counterparts in hotter climes are built to keep cool efficiently.

But these rules are less understood in humans. A small number of studies from the mid-20th century suggested a link between physiology and climate, with people from cold or high-altitude regions having proportionately stockier builds.

A recent British study of 2,600 soccer players found they have steadily been getting taller, lighter and more angular since the 1970s - replacing former key attributes of power.

Belgian international Romelu Lukaku once put his poor form down to being too muscular - rather than playing for Chelsea.

It could have an impact on recruitment. Scouts study young players' shape - as well as their technique.

Prof. Calsbeek examined 171 triathletes who competed in at least two Ironman events — one in a hot location and one in a cold climate — between 2001 and 2021.

The wealth of photos enabled digital software to measure competitors' morphology based on pictures from the bike portion of the competition.

Although bikes come in many sizes, wheel diameters are identical, which gave Prof. Calsbeek a size standard for measuring athletes from photos.

A past Ironman contestant himself, he chose to study the triathlon because the different events provide a natural control to studying how physiology determines performance.

Swimming is an activity humans are not evolutionarily developed to perform and cycling is aided by technology.

A person's performance in those events can be weighed against their aptitude at running to flesh out the influence of body type.

Prof. Calsbeek said: "A triathlon is a great human system to study because 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, so there's a great natural control.

"Male triathletes exhibited the most significant difference in performance based on physiology and the effect was most prominent in the run."

Triathlons such as Ironman and Norway's Norseman competition epitomize human endurance with competitors undertaking nearly 150 miles of running, swimming and biking in grueling conditions.

But behind the training and resilience may be basic rules of ecology that help determine the victor long before contestants leave the starting line, the study in PLOS ONE revealed.

The advantage applies to men - and not women. Lack of a significant effect of physiology on the performance of female triathletes could come down to evolution.

Prof. Calsbeek said: "This effect is likely seen only in males because natural selection acted on running performance in males to be persistence hunters."

He was inspired after observing the three-time winner of the Norseman triathlon, Allan Hovda, was stockier and shorter than one may imagine a victorious triathlete being.

Prof. Calsbeek said: "I wondered if there was something about body shape that allowed him to do better in the cold and thought about the role temperature might play for this one guy who doesn't look like your standard endurance athlete."

The findings suggest that aspiring endurance athletes may want to consider venues in climates for which their physiology is naturally attuned.

Prof. Calsbeek said: "This study included a broad sample of athletes to account for motivation and training, but the link between performance and physiology was statistically significant in spite of those factors.

"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."