Athletes are increasingly shattering world records, and it's not because they are built better, according to one doctor studying the science of exercise.

The sheer number of top-notch athletic performances is thanks to consistent advancements in technology, more efficient training and a higher concentration of participants, suggests a new study out of the Mayo Clinic in Rochester, Minn.

Mayo Clinic anesthesiologist Dr. Michael J. Joyner studied marathon and other long-distance race results over the last 125 years and found that athletes have been making dramatic leaps in performance since the 1920s. Today's athletes are faster and stronger than ever before.

For example, the pace of the men's and women's marathon today is about as fast as the 10,000-metre pace was just after the Second World War.

"It's a convergence of more and harder training, older athletes training for longer, more technology and more people," Joyner told Canada AM on Monday.

Technological advancements in bathing suits have also helped swimmers shave fractions of a second off their times. The American team's new full-piece Speedo LZR Racers, for example, emulate the characteristics of shark skin and reduce hydrodynamic drag.

Aside from improved equipment and training facilities, Joyner lists three other less-obvious factors to account for the record-breaking performances.

Prior to the First World War, athletes would train just three to four times per week for fear they would overexert themselves. It was not until the mid-20th century that athletes began training daily and for several hours at a time.

"You hear about doping today, but in the old days training was considered unethical, and people who were manual labourers were banned from competition," Joyner said

The pool of contenders is also bigger today, with more competitors from the developing world. The sports arena was dominated by North America, Western Europe and Japan for the first half of the 20th century. In the latter half of the century, Eastern Europeans and Africans began excelling in sports that don't require much equipment or infrastructure, such as soccer and marathon running.

The vast majority of swimming medals came from the U.S. until about 40 years ago, Joyner said, but as more 50-metre pools were built around the world, the nationalities of the winners began to diversify.

These days, athletes devote more time to training since careers in sport tend to last longer.

"Now you see more and more people participating for longer because the media and commercial footprint of amateur sport is so much greater and there is so much more of an opportunity for people making a living doing this," said Joyner.

It is also more likely for women to make a living from sport. Today's middle-aged woman is part of first group of women in history widely permitted and encouraged to train since childhood. It's more socially acceptable for women to compete and raise a family, Joyner said.

Joyner said records will continue to fall as people learn more efficient ways to condition their bodies and gain access to better facilities, equipment and sports medicine.