The last time Paris hosted the Summer Olympics was 100 years ago. If you were to walk into one of the dining halls at that time you would not be able to predict which sport an athlete participated. Swimmers looked like discus throwers and distance runners. David Epstein in his book, Sports Gene, suggests that as the twentieth century began, coaches and physical education teachers promoted Leonardo da Vinci’s Vitruvian Man as the model for athletic performance. Today’s Olympic athletes come in a variety of sizes, in many respects, a product of natural selection. Just take a close look at the participants who line up for the finals of any event; their bodies are very similar.

The da Vinci model was not too tall or short, muscular but not overly so. In fact, the model was rather average. Things started to change shortly after the 1924 games as fame and fortune began to follow Olympic victories. In this winner-take-all market, Olympic athletes and their bodies began to evolve. While there are some fairly specific physical requirements in a number of sports, a few attributes are still required.

Good legs are a necessity. In most sports we get our power from the ground. That means from the feet and legs to the whole body. There’s hardly a sport in the games that doesn’t require well developed legs. Even athletes in shooting must stand perfectly still, often for long periods. A second body requirement is symmetry. This is particularly important for track athletes. When you observe a runner throwing their right leg forward you will also see the left arm thrown forward to counteract the torque of the leg. This allows for smooth linear motion of the body. Sprinters need uniformity between arms and legs. If an athlete has big legs, big arms are required; little arms match little legs.

Size matters in many sports, especially height. Swimmers are generally taller as the longer body provides less fluid drag. Taller people can pull more water. Interestingly, a longer torso and shorter legs is even better. Speaking of athletes in the water, if you mistakenly walk into the locker room of a bunch of tall muscular men, wearing bathing suits, you may think you’ve entered the swim team locker room. You haven’t; you’re in the water polo dressing room. Almost all the athletes are over six feet tall and 200 pounds. Water polo not only requires constant swimming but actual physical combat with opponents; muscle is a requirement.

Basketball and volleyball players are taller. Longer arms are a big plus. Interestingly, the U.S. women’s volleyball team is taller than the basketball. Since volleyball is mostly a vertical game while basketball is horizontal and vertical, volleyballers need that height. Many athletes are average height and weight. The U.S. women’s soccer team has players as short as 5’3” and as tall as 6’. Goalies are generally bigger. Short people have an advantage in gymnastics and diving because rotation is easier with a short radius of rotation. Many of the stunts are so difficult that a taller person would just not have the time to fully rotate. In the sport of weightlifting, athletes use two different lifts, both requiring a weight to be lifted overhead. As a result, weightlifters tend to be shorter, thereby decreasing how high one has to lift the heavy barbell.

Along with height usually comes weight and that is evident in throwing events. The American shot-putters are huge. Big people have more muscle and since they have to generate tremendous force in a short distance, strength and agility are one key. Discus throwers are big but must have long arms since longer lever (the arm) has greater velocity at the end. Javelin throwers are generally big, but not as big as other throwers since they have a long runway before releasing. Rowers are big. Even though the boat is heavier when filled with big people, they make up for it with far more power. Think of putting a 10 hp motor on a boat versus a 5 hp. The 10 hp is heavier but the boat goes faster.

Distance runners tend to be smaller, with long legs and small upper bodies, helping them lose heat better. Road cyclists are smaller, especially for the hills, but indoor sprint cyclists are usually big with very muscular legs. Wrestlers are quite muscular. Body type is only one factor in success; we never know when someone comes along and breaks the mold.

Jim Johnson is a retired professor of exercise and sport science after teaching 52 years at Smith College and Washington University in St. Louis. He comments about sport, exercise, and sports medicine. He can be reached at jjohnson@smith.edu