Cardio-locomotor entrainment during walking in young healthy people. A preliminary study

The influence of the reflex neural mechanisms on the cardiovascular response during exercise can be addressed by analysing cardio-locomotor entrainment. This preliminary study provides an insight for designing a protocol to investigate cardio-locomotor entrainment during locomotion in young healthy adults. Heart rate, ECG signals and locomotor rhythm were recorded during two treadmill walking protocols which were subjected to variations in (i) speed and (ii) incline conditions. Firstly treadmill speed was increased from 100 to 140% of freely chosen walking speed (FCWS) at 0% surface incline, then treadmill surface incline was increased from 0% to 8% at 100% FCWS. The time periods between consecutive heart beats (R-R intervals) and consecutive steps (S-S intervals) were calculated, and then the phase synchronisation between the cardiac and gait rhythms was determined. Wide differences between R-R intervals and S-S intervals were observed for most of the exercise conditions, making it impossible for the development of a cardio-locomotor entrainment. When walking at 100% FCWS and 6% surface incline, R-R and S-S intervals reached similar values and a transient cardio-locomotor entrainment was observed. The results of this preliminary study suggest the need for adjusting the control parameters while investigating cardio-locomotor coupling phenomenon in healthy young adults during locomotion.