Metabolic cost, mechanical work and efficiency of lateral walking

Lateral walking is an asymmetrical gait, mainly used in sports or working tasks, characterised by higher oxygen demand compared to forward walking. Comprehensive analyses of its mechanical efficiency-the mechanical work produced over the metabolic cost-are lacking. The purpose of this work is to fill this gap of knowledge.

Twenty-four healthy and active young adults (13 females, 11 males) completed controlled treadmill tests adjusted to their self-selected lateral walking speed (SSLWS) and free tests on a flat surface. Four treadmill speeds (±20%, SSLWS and +40% of SSLWS) were tested. Metabolic data were collected via indirect calorimetry, while mechanical work was estimated from 3D motion capture data. Data was analyzed by comparing the results at different speeds and using regression models.

Cardiorespiratory demand was moderate but, due to the low speed, the cost of transport (~7 J·kg⁻¹·m⁻¹) was more than double that of walking at self-selected speed. The mechanical work was comparable to walking, which resulted in lower estimates of mechanical efficiency (~12%). Treadmill trials showed higher metabolic demand than free overground lateral walking.

In healthy young adults, the combination of modest absolute cardiorespiratory load with high metabolic cost per unit distance suggests that lateral walking may be useful for low-intensity training and merits further investigation as a rehabilitation gait in clinical populations, where metabolic demand without high cardiovascular stress is desired.