Validity of a simple sit-to-stand method for assessing force-velocity profile in older adults

Lower limb muscle strength is an important determinant of physical function in older adults. However, its measure in clinical settings is limited because of the requirement for large-scale and costly equipment. A new simple protocol based on sit-to-stand test (STS) is developed to measure force velocity (F-v) and power velocity (P-v) profile in the community-dwelling older adults. The objective of this study was to assess the validity of this new methodology for measuring F-v and P-v profile compared to the gold standard isokinetic BIODEX. 46 older people aged 65–85 years (M = 73.7; SD = 7.7). F-v and P-v profiles were assessed in participants on their dominant leg. The concurrent validity of STS was tested using Spearman's rank correlation coefficient and Passing Bablok: maximal power output Pmax, optimal velocity and force Vopt and Fopt, maximal force at null velocity F0, maximal unloaded velocity V0 and coefficient of F-v (SFV) and P-v equation (a_poly, b_poly). No proportional difference for F0 and b_poly and a low significant correlation for Pmax (r = 0.314), Sfv (r = 0.229), a_poly (r = 0.335) and b_poly (r = 0.226) whereas the other parameters were non correlated significantly. STS method is moderately reliable on force and power parameters whereas further improvements are needing for velocity parameters. However, its feasibility, portability and lower cost compared to other methods makes it very affordable in clinical context and will allow easy investigation of aging population. •The STS method is portable, quicker and less expensive than the existed methods (isokinetic or leg press).•Isokinetic knee extension method and STS may not be used interchangeably as calculation and protocols are very different.•Force and power’s parameters were more reliable than velocities’ one as isokinetic method is based on fixed known velocities while STS is participant-dependent.•This method could be helpful to detect a muscular impairment, frailty or comorbidities in clinical evaluation.