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Introduction: The Five-times Sit-to-Stand test (STS) is a commonly used functional screening test in older people. It also forms part of the diagnosis for sarcopenia. In addition to the time taken to complete the 5STS, instrumented versions of the test can be used to evaluate the velocity at which each STS is performed. The aim of this study was to develop an automatic system to measure STS velocity using an instrumented chair. Material & Methods: An instrumented wooden chair was constructed using four load cells fixed on the seat of the chair, which were then covered by an additional piece of wood. Signals from the load cells were sampled at 80 Hz for a group of 16 older people while they performed the 5STS. Velocity of each STS was derived using Newton's second law of motion, with STS velocity calculated using the rate of force development during each sitto- stand movement. The STS velocity was compared to functional screening tests including gait velocity and grip strength. Results: The STS velocity obtained from the chair was similar to the values obtained by motion capture. In addition, STS velocity from the instrumented chair had higher correlations with both gait velocity (r=0.76) and grip strength (r=0.62), then the correlations between STS time and gait velocity (r=0.27) or grip strength (r=0.34). Conclusions: The instrumented chair was able to accurately measure STS velocity which is more closely related to other functional tests than 5STS time. [ABSTRACT FROM AUTHOR]