Background. Ultimate goal for the treatment of the deformities in the lower extremities is to minimize the energy requirement and conserve the energy on walking and daily living. The normal energy saving mechanism is usually broken down in the patients with the deformities in the lower extremity, and they need more energy consumption. This is the reason why they feel fatigue frequently. It is well known that the deformity in the lower extremity cause excessive energy consumption. Objectives. There is no report that compared the energy consumption according to the deformities of the lower extremity. When we decide the priority of the treatment in cases of multiple deformities, it will be important to understand the energy demand according to each deformity. Therefore, it is the purpose of this study that assess the energy consumption according to the various types of lower extremity deformities. Method. We induced the multiple deformities in ten normal adults with the brace artificially. The induced deformities are as follows: Equinus deformity; mild (10degrees), moderate (20degrees), severe (30degrees), Knee flexion deformity; mild (10degrees), moderate (20degrees), severe (30degrees), Hip flexion deformity; mild (10degrees), moderate (20degrees), severe (30degrees). For the control group, same braces were applied without any deformity. Oxygen consumption was measured for the energy consumption with the Oxygen Consumption Meter (Morgan Oxylog II, Morgan Ltd. England). Heart rate was checked with the Telemonitor (Dynascope, Fukuda Ltd, Japan). We evaluated the inspired volume, oxygen rate, oxygen cost, and heart rate in each group and compared the data among the groups. Result. Energy consumption was higher in the hip deformity group, in the knee deformity group, and in the ankle deformity group in that order. Conclusion. When there are concomitant deformities in hip, knee and ankle, the priority of treatment may be hip, knee and ankle, in that order in terms of energy consumption.