30-second chair stand test
The 30-second chair stand test (30s CST) is a test of sitto-
stand ability, lower limb strength and dynamic balance
[29]. Starting from a seated position, the patient
stands then sits as many times as possible in 30 seconds
[49]. The chair is a straight back chair with a 44 cm seat
height, preferably without arms. If the patient cannot
stand without using their arms, their hands can be placed on their legs and recorded as an adapted test score [29].
An initial practice trial will be performed to reduce any
practice effect [50]. In a population with end stage hip or
knee OA awaiting joint replacement surgery, intra-tester
reliability (ICC (1,1)= 0.97-0.98, 95 % CI = 0.94-0.99) and
inter-tester reliability (ICC (1,1) 0.93- 0.98, 95 % CI = 0.87-
0.99) were excellent [50]. Convergent validity was evident
by a moderate correlation (Spearman’s rho=0.64 (95 % CI
0.49 to 0.75)) with other measures of physical function.
Discriminant validity was evident by low correlation
(Spearman’s rho = 0.33 (95 % CI 0.12 to 0.51)) with mental
health scores. Known groups validity was demonstrated by
significantly higher scores recorded for participants who
ambulated without a gait aid compared to participants
who did not with a mean difference of 2.8 (95 % CI 1.4 to
4.1) and effect size of 0.64 (95 % CI 0.32 to 0.95). Standardized
response mean of 0.84 (95 % CI 0.61 to 1.07) indicates
the 30s CST is a responsive measure [51].