We estimated energy expenditure with the Physiological
Cost Index (PCI) [35]. The PCI was assessed on a treadmill.
First, participants stood still for 2 min and the mean
heart rate of the last 10 s was used as heart rate at rest.
Then they walked for 3 min at the same speed as previously
determined in their first 10MWTat preferred speed.
The PCI was calculated as follows: PCI = (steady-state
heart rate – heart rate at rest)/ambulatory velocity