['Determining gait speed as a measure of physical performance is recommended in diagnosing sarcopenia. Gait speed measurements require a certain amount of space (e.g. a 6-m course), and might not be feasible in clinical settings or heath checkup examination sites. We developed a formula to estimate chair stand time based on gait speed, and examined the validity (sensitivity and specificity) of using the estimated chair stand time cut-off point as a surrogate for the recommended gait speed cut-off point.', 'Chair stand time was defined as the time it took to stand up from a standard chair five times. Gait speed was calculated from the time required for participants to walk a 6-m course at their usual pace.', 'Simple regression analysis showed a significant negative relationship between chair stand time and gait speed (P\u2009<\u20090.0001), and the estimated formula was derived as follows: five times chair stand time\u2009=\u2009-8.41\u2009×\u2009gait speed\u2009+\u200920.0 (R'] Do usefulness of chair stand time as a surrogate of gait speed in diagnosing sarcopenia?