ANALYSIS OF THE SIT-STAND-SIT MOVEMENT CYCLE IN NORMAL SUBJECTS

Objective. This study aimed to establish a basis of descriptive data f or the sit-stand-sit movement cycle in 50 normal subjects, 25 male and 25 female, aged between 20.1 and 78.3 years (mean age 46.8 years). De sign. A descriptive design was employed to establish the characteristi cs of the activity in normal subjects. Background. Research has been c arried out into kinetic and kinematic characteristics of the sit-to-st and movement, but few researchers have considered stand-to-sit. Most s tudies have involved small samples, subjects with pathology, or elderl y subjects, so a baseline of data from normal subjects has not yet bee n established. Method. Linear displacement and acceleration of the tru nk and angular displacement of the knee were recorded simultaneously w ithin the same temporal framework. The measurement system consisted of a vector stereograph, and triaxial accelerometers located at the leve l of C-7, and an electrogoniometer located at the lateral aspect of th e knee. Subjects rose from and descended to the seated position a tota l of six times at their own self-selected speed. Numerical data were s ubjected to descriptive analysis, matched-pairs t tests and Pearson's rho correlations. Results. Mean values for the time to rise was 1.91 s and to descend was 1.97 s. Forward lean velocity was greater during r ising than descending (P<0.001), and recovery velocity was greater dur ing descending than rising (P<0.001). Temporal contributions of forwar d lean and vertical displacement and the period of overlap between the m were identified, and relationships between acceleration and temporal events and components were established. Differences existed among gro ups, involving primarily the elderly groups and occurring during the r ising phase. Conclusions. This study has proposed a baseline of descri ptive data in normal subjects for the sit-stand-sit movement cycle. Re levance In practical and clinical applications of information gained f rom analysis of functional activities, establishment of what is accept ed as 'normal' is necessary before abnormalities can be identified and analysed, and intervention implemented and evaluated. This study prov ides that basis. (C) 1997 Elsevier Science Ltd.