I do not believe that there is a 'best' method, Senne, because it depends on the problem you want to solve with the use of the ankle-foot exoskeleton.

My first interest would be related to gait speed, step length, and stance/swing phase duration. Given that the subjects have some kind of limitations in their gait performance, I would hope that the use of such an assistive device - if if works well - should improve their temporal-spatial characteristics, i.e. they should be able to walk faster and with longer steps that might have been shorter than normal without the device.

Furthermore, it should be interesting to determine whether the assistance also helps to conserve energy, i.e. measuring their oxygen consumption would eventually make sense.

Lateron, I would of course be interested how the added plantarflexion moment (I assume that this is what the device provides during gait) affects the joint moments in the more proximal joints, i.e. in the knee and hip.

So in essence: No best method, but several valid and meaningful aspects to consider.

Thank you for the answer Prof. Rosenbaum

Indeed. Perhaps there is no "best" method to measure this parameter. Because we are interested in metabolic cost on the one hand, we will try to determine adaptation by looking for a steady-stade phase in metabolic cost.

On the other hand, we will also take a look at the ankle joint kinematic correlation common variance and at the linear correlation between baseline and powered ankle joint kinematic patterns. I hope this will give us a better understanding in the adaptation to such devices.

This depends on the type of sport practiced