Washington, Jan 26 (Calcutta Tube) Jamaican sprinter Usain Bolt’s record-setting performances have unleashed a wave of interest in the ultimate limits to human running speed.
New evidence offers an enticing view of how the biological limits might be pushed back beyond the nearly 45 kmph achieved by Bolt to speeds of perhaps 64 kmph, speeds achieved by Hollywood creation Terminator.
The study was authored by Peter Weyand of Southern Methodist University (SMU); Rosalind Sandell and Danille Prime, both formerly of Rice University; and Matthew Bundle of the University of Wyoming.
‘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 Weyand, associate professor of applied physiology and biomechanics at SMU in Dallas.
‘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,’ said Weyand.
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 tenth of a second, and peak ground forces occur within less than twentieth of one second of the first instant of foot-ground contact.
The researchers took advantage of several experimental tools to arrive at the new conclusions, said an SMU release.
They used a high-speed treadmill capable of attaining speeds greater than 64 kmph and of acquiring precise measurements of the forces applied to the surface with each footfall.
These findings were published in the Journal of Applied Physiology.