Energy consumption during level walking with arm and knee immobilized.

OBJECTIVE

To determine whether there is an increase in energy use for able-bodied subjects with their arm and/or knee immobilized, while walking on a level surface at comfortable walking speed (CWS).

DESIGN

Prospective, quantitative, with randomly sequenced experimental trials.

SETTING

Rehabilitation center.

PARTICIPANTS

Ten healthy subjects, none of whom had gait abnormality.

INTERVENTION

Subjects walked on a treadmill at CWS under 4 conditions: (1) without an arm or knee immobilized (N); (2) with an arm immobilized (AI); (3) with a knee immobilized (KI); and (4) with both arm and ipsilateral knee immobilized (KAI).

MAIN OUTCOME MEASURES

Breath-by-breath oxygen cost; differences in energy consumption in trials during which constraints were used were compared with energy consumed under the N condition and the percentage of change was calculated.

RESULTS

Mean oxygen cost increased by 22.7% with a knee immobilized compared with N values (mean difference,.044 mL x kg(-1) x m(-1), p <.0001), and increased by 24.7% with a knee and arm immobilized (mean difference,.048 mL x kg(-1) x m(-1), p <.0001). However, no significant differences existed in oxygen cost with AI compared with N, or with KAI compared with KI. The differences in CWS between the stages followed a similar pattern.

CONCLUSIONS

Arm immobilization does not increase energy expenditure during level walking at CWS, and does not further increase energy expenditure when the ipsilateral knee also is immobilized.