Does cardio-respiratory response underlie the gait transition phenomenon?

Abstract

Gait reorganization is multifactorial phenomenon influenced by biomechanical, energetic, mechanical and perceptual factors. Problem Statement: Despite the existence of several studies on this topic, it is not clear exactly how cardiorespiratory loading and metabolic demands influence the initiation of gait reorganization. Purpose: The purpose of this study was to define the cardiorespiratory response during walking and running at speeds corresponding to PTS. Approach: The sample included 26 male subjects, homogenized with respect to age and anthropometric dimensions. Cardiovascular and respiratory variables were measured during walking and running at five previously determined speeds above and below preferred transition speed (PTS). Results: Heart rate (HR), oxygen uptake (VO2) and carbon dioxide production (VCO2) increased linearly with acceleration, during both forms of locomotion. Post-hoc analysis revealed a significant difference (p<0.01) between all adjacent speeds during walking and running. At PTS and speeds above the PTS, breathing frequency (BF) was higher during walking and significance was obtained at a speed of 8.8 km/h (∆=8.89 bpm, p=0.002). Increase in walking speed significantly influenced increase in BF (p<0.001, ή2=0.817) and ventilation (p<0.001, ή2=0.913), while at the same time didn’t affect the changes in ventilator equivalents. The main finding of this study is that walking at speeds above PTS, require significantly higher exertion of cardiovascular and respiration system in compare to running. Also, running below the PTS is energetically and functionally inefficient locomotion pattern, due to significantly higher oxygen consumption, ventilation and oxygen pulse. Thus, the most significant functional capacity variables as HR, VE and VO2 had lower values during walking below and running above PTS which implies the influence of cardio-respiratory variables in gait reorganization. Conclusion: This study showed that transition from walking to running leads to a significant decrease in cardiovascular and respiratory systems loading. Thus, we can conclude that physiological underlying mechanisms of human gait transition are relevant for PTS phenomenon.