Much of this research came from the mind and laboratory of Daniel Lieberman, professor of evolutionary human anatomy at Harvard University and author of the new book “Exercised”, which looks at exercise and evolution. . At first, most of his work and that of other evolutionary and running scientists focused on the lower body, as the legs play such an obvious role in how we travel from one to the other. place to place.
But Dr Lieberman was also interested in the runners’ upper body and, in particular, their head. As a longtime marathoner himself, he knew that a stable head is essential for a successful run, but not necessarily a simple thing to achieve. Running is propulsive. You push, get up and then brake forcefully against the ground with each stride, placing forces on your head that could cause it to fall uncontrollably, like that wobbling ponytail.
However, it hasn’t been entirely clear how we manage to keep our heads steady. Like most cursive species or running animals, including dogs and horses, we have a well-developed nuchal ligament, a tissue that connects the skull and neck. This is not the case in species that are not natural runners, such as monkeys or pigs.
When he was a young scientist, recalls Dr. Lieberman, he drew pigs – who are ungainly runners – onto treadmills to study their biomechanics. Their heads twitched like bobbleheads when forced to run, prompting Dr. Lieberman and his colleagues to conclude that they did not have a nuchal ligament, a finding confirmed by anatomical studies.
But we humans also have the challenge of standing on two legs. Presumably to balance ourselves while running, at one point we started swinging our arms. Dr. Lieberman guessed that the swing of the arms helped stabilize our heads. But, if it did, there should be coordination between the muscles in our forearms and shoulders, he thought, even though those muscles don’t physically connect. They would need to pull together and with comparable force during the race, if they were to succeed in stabilizing our heads.