Deficits in lower extremity muscle and gait performance among renal transplant candidates

This study was performed to determine the reliability and convergent validity of two lower extremity muscle performance (LEMP) measurements and to describe deficits in and determinants of LEMP and gait performance. Cross-sectional case series and criterion standard designs were used. The study took place at a tertiary care center. The subjects were referred from a volunteer sample of 110 renal transplant candidates. There were no interventions. The main outcome measures were knee extension strength measured by hand-held dynamometry and a sit-to-stand-to-sit (STSTS) test; gait independence on level surfaces and stairs; comfortable and maximum gait speed. Dynamometer measurements were reliable within (intraclass correlation coefficient (ICC) > or = .976) and between (ICC > or = .953) testers. Repeated STSTS measurements were also reliable (ICC > or = .843). The LEMP measures correlated significantly (p < .001) with one another (r > or = .406, R > or = .445). Compared with values predicted by regression equations derived from healthy individuals, transplant candidates showed significant deficits in knee extension force (33.2% to 34.6%) and gait speed (20.5% to 22.7%). Consistent as determinants of LEMP were sex, weight, and diabetic status. STSTS performance was the most consistent determinant of gait performance. The results of this study support the use of the STSTS test to characterize LEMP in kidney transplant candidates, particularly those who are diabetic or have deficits in gait performance.