The Physiological Cost of Restricted Weight Bearing

Background: To identify the energy cost of placing restrictions on weight bearing status.

Methods: Measurement of the Physiological cost index (PCI) for 11 healthy volunteers carrying out three types of mobilisation over a 100 m course in a physiology laboratory: normal walking fully weight bearing (FWB); non-weight bearing (NWB) and feather touch weight bearing (FTWB). NWB and FTWB were performed using a walking frame for support. FTWB was defined as mobilisation with the foot flat, as in normal gait, but with less than 100 N force generated through the limb.

Results: Both NWB and FTWB developed significantly greater PCI than normal walking. There was no physiological cost benefit of FTWB over NWB, p=0.67, but FTWB was perceived by all participants to be less tiring.

Conclusions: Restricting weight bearing status significantly increases energy expenditure; the PCI. FTWB may be a more tolerable form of restricted weight bearing, although the PCI does not reflect this perception. These findings should be borne in mind when recommending such restrictions in clinical practice and encouraging a patient to mobilise early and effectively.