Comparison of two popular transducers to measure sit-to-stand power in older adults.

The Tendo Unit (TU) and GymAware (GA) are the two most frequently used linear transducers for assessing muscle power in older adults via the sit-to-stand (STS) test. Unlike TU, GA incorporates a sensor mechanism to correct for non-vertical movements, which may lead to systematic differences between devices. The aim of this study therefore was to compare GA to TU for measuring STS power in community-dwelling older adults. Community-dwelling adults (n = 51, aged ≥65 years, 61% female) completed a single chair stand, with peak power measured simultaneously using GA and TU. Participants also completed the pneumatic leg press, 8-Foot Up and Go (TUG) test, Short Physical Performance Battery (SPPB), and self-reported measures of physical function. Intraclass correlations (ICC) were used to assess agreement, and Pearson's correlations were used to assess correlations. The study protocol was prospectively registered on the Open Science Framework. In alignment with our pre-registered hypothesis, peak power demonstrated an ICC of 0.93 (95% CI: 0.88, 0.96). For secondary aims, both transducers showed a correlation greater than 0.8 compared to pneumatic leg press power. For physical performance outcomes, both TU and GA showed similar correlations, as hypothesized: SPPB (r = 0.29 for TU vs. 0.33 for GA), Chair Stands (r = -0.41 vs. -0.38), TUG Fast (r = -0.53 vs. -0.52), mobility questionnaire (r = 0.52 vs. 0.52) and physical function questionnaire (r = 0.44 vs. 0.43). GA and TU peak power showed a high degree of agreement and similar correlations with physical and self-reported performance measures, suggesting that both methods can be used for assessing STS power in older adults.

Criterion Validity and Reliability of 2 Brief Physical Activity Questionnaires in Ethnically Diverse Adults.

PURPOSE: The study compares moderate- to vigorous-intensity physical activity (MVPA) as evaluated by the Exercise Vital Signs (EVS) and Physical Activity Vital Signs (PAVS) questionnaires to accelerometry, and evaluates the reliability of the questionnaires in ethnically diverse adults. METHODS: Ninety-nine participants (mean age 38.1 y; 49.5% women; Hispanics 43.8%; European American 18.8%; African American 14.6%) were included in the analyses. Participants wore an accelerometer at the hip for at least 7 days and completed the EVS and PAVS questionnaires at the beginning (T1) and at the end (T2) of the 7 days. Associations between the questionnaires and accelerometry were examined using Spearman rho. The reliability of the questionnaires was evaluated using intraclass correlation coefficient. Sensitivity and specificity were also calculated. RESULTS: Weak positive correlations were observed between the accelerometer MVPA and the EVS MVPA at T2 (ρ = .263, P = .013), and the PAVS MVPA at T2 (ρ = .327, P = .003). The sensitivity of the EVS and PAVS was 73.2% and 82.6%, respectively. The specificity for each questionnaire was 35.3%. The reliability for the EVS questionnaire (intraclass correlation coefficient = .855; 95% CI, .791-.901; P < .001) was good, while the reliability of the PAVS questionnaire (intraclass correlation coefficient = .652; 95% CI, .511-.758; P < .001) was moderate. CONCLUSION: Caution should be used when utilizing the EVS and PAVS questionnaires in ethnically diverse adults.

Characterizing Heart Rate Variability Response to Maximal Exercise Testing in People with Huntington's Disease.

Background: Huntington's disease (HD) is an autosomal dominant, neurodegenerative disease that involves dysfunction in the autonomic nervous system (ANS). Heart rate variability (HRV) is a valid and noninvasive measure for ANS dysfunction, yet no study has characterized HRV response to exercise in people with HD. Objective: Characterize HRV response to exercise in individuals with HD and explore its implications for exercise prescription and cardiac dysautonomia mechanisms. Methods: 19 participants with HD were recruited as part of a cohort of individuals enrolled in the Physical Activity and Exercise Outcomes in Huntington's Disease (PACE-HD) study at Teachers College, Columbia University (TC). 13 non-HD age- and gender-matched control participants were also recruited from TC. HRV was recorded with a Polar H10 heart rate (HR) monitor before, during, and after a ramp cycle-ergometer exercise test. Results: Participants with HD showed reduced HR peak (p < 0.01) and HR reserve (p < 0.001) compared with controls. Participants with HD demonstrated reduced root mean square of successive differences between normal-to-normal intervals (RMSSD) and successive differences of normal-to-normal intervals (SDSD) at rest (p < 0.001). Participants with HD also showed differences for low frequency (LF) power (p < 0.01), high frequency (HF) normalized units (nu) (p < 0.05), LF (nu) (p < 0.001), and HF/LF ratio (p < 0.05) compared with controls. Conclusions: We found reduced aerobic exercise capacity and sympathovagal dysautonomia both at rest and during post-exercise recovery in people with HD, suggesting modified exercise prescription may be required for people with HD. Further investigations focusing on cardiac dysautonomia and underlying mechanisms of sympathovagal dysautonomia in people with HD are warranted.