Analysis of the Effect of Lower Limb Weakness on Performance of a Sit-stand Task (draft)

The objectives of this research were: 1) to determine how the use of upper extremities to assist during a chair rise task affects lower extremity loading; 2) to examine how task difficulty affects performance when weakness is present; and 3) to compare the compensation strategies utilized by individuals with chronic weakness to those used by patients with acute weakness. Twelve polio survivors with predominant unilateral weakness of the knee extensors and six adults with no history of polio who had recently undergone unilateral knee surgery participated in this study. The sit-stand task was performed under four different conditions that varied by chair height and/or use of armrests. The results showed that the compensation strategies utilized by the polio survivors and surgery patients were similar, although the polio survivors showed a higher degree of asymmetric weight bearing, especially in the most difficult condition. These results may be helpful in predicting sites for future overuse problems.