Parameters and Mechanical Description of Lateral Walking

Lateral walking (LW) presents an asymmetric pattern, with a different mechanical and kinematic behavior than conventional walking. LW is used in sports, rehabilitation and work tasks, although knowledge of its mechanical behavior is still missing. The aim was to compare measurements of space-time parameters, mechanical work and recovery. 11 men and 13 women were evaluated while LW on a treadmill at 4 different speeds, self-selected lateral walking speed (SSLWS), ±20% and + 40%, in both directions. A motion capture system (Vicon, UK) was used to record at 100 Hz the displacement of 11 body segments. The trajectories of the body centre of mass and the segments were reconstructed and the mechanical work determined. The LW strides were identified and cut by analysing the vertical velocity of the 5th metatarsal marker. Step frequency and length increased with speed in both directions, while duty factor decreased with increasing speed. Total mechanical work (Wtot) is calculated as the sum of external work (Wext) and internal work (Wint). Wtot increased with speed and the highest recovery percentage corresponded to the SSLWS. The external work accounted for 68.6 and 61.4% of the total mechanical work toward left and right. The vertical energy curve is bimodal, with a slight dip between two peaks in the double support position with both limbs parallel. Special populations, such as neurological, orthopedic, or sports rehabilitation patients, may benefit from programs that consider characteristics such as duty factor, recovery percentage, and spatiotemporal characteristics of LW other than conventional gait.