A new study published in the Journal of Applied Physiology offers intriguing insights into the biology of human running speed.
It also offers an enticing view of how the biological limits might be pushed back beyond the nearly 28 miles per hour speeds achieved by Usain Bolt to speeds of perhaps 35 or even 40 miles per hour.
“The prevailing view that speed is limited by the force with which the limbs can strike the running surface is an eminently reasonable one,” said Peter Weyand, the author of the report.
“If one considers that elite sprinters can apply peak forces of 800 to 1,000 pounds with a single limb during each sprinting step, it’s easy to believe that runners are probably operating at or near the force limits of their muscles and limbs,” he said.
“However, our new data clearly show that this is not the case. Despite how large the running forces can be, we found that the limbs are capable of applying much greater ground forces than those present during top-speed forward running.”
In contrast to a force limit, what the researchers found was that the critical biological limit is imposed by time – specifically, the very brief periods of time available to apply force to the ground while sprinting
In elite sprinters, foot-ground contact times are less than one-tenth of one second but peak ground forces occur within less than one-twentieth of one second of the first instant of foot-ground contact.
The researchers said the new work shows that running speed limits are set by the contractile speed limits of the muscle fibres themselves, with fibre contractile speeds setting the limit on how quickly the runner’s limb can apply force to the running surface.
“Our simple projections indicate that muscle contractile speeds that would allow for maximal or near-maximal forces would permit running speeds of 35 to 40 miles per hour and conceivably faster,” said research team member, Matthew Bundle.
Source: Medical News Today
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