Mechanical work and energy of sit-to-stand and stand-to-sit transitions performed with traditional and dynamic office chair designs

BACKGROUND: Adherence to sit-stand workstation usage has been shown to decrease post-intervention, with the reported reasons related to fatigue, cumbersome workstation adjustments, and focus. OBJECTIVE: To characterize the mechanical work and total energy required to perform transitions from a traditional office chair and a dynamic chair designed specifically for sit-stand workstations. The whole-body, thigh, and shank centre-of-mass (CoM) were evaluated. METHODS: Fifteen participants (8 male; 7 female) performed three intermittent sit-to-stand and stand-to-sit transitions from the traditional and dynamic chairs. Kinematic data of the trunk, pelvis, and lower extremities were collected using an optoelectronic motion capture system and triaxial accelerometers. The change in total energy and work between the sitting and standing postures were evaluated for each CoM point. Lumbar spine range-of-motion was further assessed between chair conditions. RESULTS: Chair designs facilitated opposite work and energy responses for a given transition. Transitions performed from the dynamic chair reduced the work and total energy of the whole-body CoM, by +/- 8.5J and +/- 214.6J (p < 0.001), respectively. The work and energy of the thigh CoM differed within transitions (p < 0.001), but the positive and negative components were similar between chairs (work =+/- 0.18J, energy =+/- 0.55J). The dynamic chair increased the total energy (+/- 38.3J, p < 0.001) but not the work of the shank CoM (+/- 1.1J, p >= 0.347). CONCLUSION: The required mechanical work and energy of sit-to-stand and stand-to-sit transitions was