There were just two running world records broken at the Rio Olympics in 2016: Wayde van Niekerk, from South Africa, in the men's 400m and Almaz Ayana, from Ethiopia, in the women’s 10,000m.
Then, at this year's athletics world championships in London, only one athlete succeeded in breaking a world-record. That honor went to Portugal's Ines Henriques for the women's 50km race walk. Although an extremely impressive personal achievement, the fact that it was a record-breaker is not exactly surprising seeing as it was the very first year the event was contested. (Organizers introduced the event to ensure gender equality. Men have been able to compete in the 50km race walk since 1932.)
This might not be a short-term dip in record-breaking moments, experts say. It could be the start of a new, long-term trend.
While improvements in training and nutrition in the 20th century saw athletic achievement improve in leaps and bounds, many scientists believe we're now extremely close to reaching the human body's full potential for endurance sports. This means that the era of record-breaking, at least as far as professional runners are concerned, could be coming to an end. To break the natural limits of human physiology and beat existing records, athletes may have to turn to artificial technology and doping.
This argument is backed up by research. In 2008 – before Usain Bolt smashed existing records for the men's 100m in 2009 – a study found that athletes have already accomplished 99 percent of what is physically possible according to human biology.
Many factors are needed to make the "perfect" runner. Vincent Pialoux, deputy head of Lyon's Inter-University Laboratory of Human Movement Biology, identified "three major physiological and biomechanical criteria” in an article published by AFP. These are endurance, the ability to create energy using oxygen, and motor efficiency (an athlete’s ability to save energy).
"Of these three factors, if we take the best data measured in the laboratory on different athletes, we arrive at times well below the limits predicted" by models based on the evolution of performance, he said.
No professional athlete has ticked all the boxes so the "perfect" runner is, at least for the time being, strictly theoretical. Still, now that we are approaching our biological limitations, will we see more incidents of doping, stem-cell therapy, and genetically engineered athletes?
"The transformation of man into an animal capable of running a marathon in one hour and 40 minutes would take a long time, if it is possible, and there are an incalculable number of scientific limits," added performance expert Pierre Sallet from Athletes for Transparency.
And, as he pointed out, "there will always be one limit: keeping the person alive."