As discussed, walking speed has previously been shown to influence variability in lower limb step kinematics. Near the walk–run–walk transitions, stride duration increases before and after the transition , and increases at slower walking speeds (0.2–0.6 m s−1) compared with speeds of 0.8–1.4 m s−1. A linear increase in variability is present in joint angles , step length , step time interval  and step impulse . Irrespective of the variable being measured, the data most commonly follow a U-shaped function at speeds faster and slower than comfortable walking speed, [1,53,54,56–58]. When younger and older adults are compared, stride time variability, and variability in frontal hip and knee motions, knee internal and external rotation, trunk motions  and step width  increased with speed in older adults. While the magnitude of variability is greater in older adults (more than 65), the variability–speed relationship is consistent between younger and older adults . The observed difference here could be due to the fact that plantar pressure is not kinematic but kinetic, and this warrants further investigation.