Ankle joint load and leg muscle activity during lifting.

The load on the talocrural joint during three different ways of lifting was compared and discussed with biomechanical and ergonomical aspects. Healthy subjects lifted a 12.8-kg box from floor to table-level with bent and straight knees. The loading moment of force about the bilateral ankle axis was calculated by means of a computerized static sagittal plane model. Electromyography was recorded from the tibial anterior, gastrocnemius, and soleus muscles. The mean maximum loading moment was found to be 68 newton-meters with an estimated joint compressive force of 2.9 times body weight. The lowest loading moments obtained were associated with lifting the burden between bent knees and close to the pelvis.