Why do tall people move more slowly

Science in dialogue

Can people with long legs run faster than people with short legs?

Definitely not. If you have longer legs, you take longer steps, but the sequence of steps is slower. If you have shorter legs, you take shorter steps, but the sequence of steps is faster. The bottom line is that both can cover a short distance that does not depend on their stamina at the same time.

The fact that a person with longer legs has a slower sequence of steps is due to the moment of inertia. The bigger it is for a body, the slower it can accelerate. A long leg has a greater moment of inertia due to its greater mass. In addition, the moment of inertia increases with the square of the distance from the axis of rotation. The further the mass is from the hip joint - the axis of rotation of the leg - the greater the moment of inertia. With a longer leg, the foot with the sneaker is further away and therefore the moment of inertia is greater than with a shorter leg. This effect can be illustrated with a figure skater. If he stretches his arms out during a pirouette, he slows down, if he takes them close to his body, he speeds up.

Whether a person can run very quickly depends essentially on two parameters: On the one hand, how quickly the nerve impulses, i.e. the commands to move the leg, are transmitted from the brain to the muscles. On the other hand, it is crucial how quickly the muscles react to this command and how quickly they contract. These parameters are largely innate and can therefore hardly be trained. They therefore fall into the talent category. For speed on short distances, however, training can improve muscle strength and the coordination of the muscles during fast movements.

The fact that leg length does not play a role can be seen not least from the fact that athletes with both short and longer legs are represented among the world's top sprinters.

The question was answered by Dr. Rüdiger Preiß from the Institute for Sports Science at the University of Frankfurt am Main.