Comparison Of Two Popular Linear Transducers To Measure Sit-to-stand Power In Older Adults

PURPOSE: The Sit-to-Stand (STS) power test, employing a linear transducer, is a widely utilized method for evaluating lower body power in older adults. The Tendo Unit (TU) and the Gym Aware (GA) are the two most frequently employed linear transducers. GA utilizes a spool mechanism to account for non-vertical movement, while TU does not adjust for changes in the vertical angle of lift. Despite these differences, no study has yet systematically compared the two transducers. METHODS: Fifty community-dwelling adults, aged 65 years or older, were recruited. Lower-body STS power was assessed using both the GA and the TU for the same chair stand. The highest peak power across three attempts, with one minute of rest in between, was used for the analysis. Participants also completed the 8-Foot Up and Go (TUG) test and the Short Physical Performance Battery (SPPB), which includes assessments of balance, usual walking speed, and chair stand test. Intraclass correlations (ICC) were calculated using a two-way random-effects model for absolute agreement of single measure. Pearson’s correlation coefficient was used to examine correlations. Sample size, analysis, and hypotheses were pre-registered on the Open Science Framework (OSF). RESULTS: The mean age of the sample was 70.8 years, with 60.8% being females. According to our pre-registered hypothesis, peak power demonstrated an ICC of 0.93 (95% CI: 0.88, 0.96), exceeding our minimum threshold of 0.75, while average power had an ICC of 0.81 (95% CI: 0.73, 0.87). For secondary aims, the Pearson correlation for peak power between the TU and GA showed a strong correlation of 0.96 (95% CI: 0.93, 0.98). Regarding physical performance outcomes, both TU and GA showed similar correlations (within 0.1), as hypothesized, for peak power: SPPB (r = 0.29 for TU vs. 0.33 for GA), Chair Stands (−0.41 vs. -0.38), TUG Fast (−0.53 vs. -0.52), and Balance (0.12 vs. 0.16). Bland-Altman plots revealed a mean difference of 92 W for peak power, with limits of agreement ranging from -112.0 W to 296.4 W CONCLUSIONS: GA and TU peak power showed a high degree of absolute agreement and similar correlations with performance measures, suggesting that both methods can be used interchangeably for assessing STS power in older adults. PSC CUNY