The purpose of this study was to determine the dose-response association between habitual physical activity (PA) and cognitive function using a nationally representative dataset of U.S. older adults aged ≥ 60 years. We used data from the 2011–2014 National Health and Nutrition Examination Survey (n = 2441, mean [SE] age: 69.1 [0.2] years, 54.7% females). Cognitive function was assessed using the Digit Symbol Substitution Test (DSST) and Animal Fluency Test (AFT). Habitual PA was collected using a tri-axial accelerometer worn on participants’ non-dominant wrist. PA was expressed as two metrics using monitor-independent movement summary (MIMS) units: the average of Daily MIMS (MIMS/day) and peak 30-minute MIMS (Peak-30_MIMS; the average of the highest 30 MIMS mins/day). Sample weight-adjusted multivariable linear regression was performed to determine the relationship between each cognitive score and MIMS metric while adjusting for covariates. After controlling for covariates, for each 1000-unit increase in Daily MIMS, DSST score increased (β-coefficient [95% CIs]) by 0.67 (0.40, 0.93), while AFT score increased by 0.13 (0.04, 0.22); for each one-unit increase in Peak-30_MIMS, DSST score increased by 0.56 (0.42, 0.70), while AFT score increased by 0.10 (0.05, 0.15), all p-values <0.001. When including both MIMS metrics in a single model, the association between Peak-30_MIMS and cognitive scores remained significant (p-values <0.01), whereas Daily MIMS did not. Our findings suggest that higher PA (both daily accumulated and peak effort) is associated with better cognitive function in the U.S. older adult population.

We documented reporting and rates of drop-out, adherence, and compliance from 40 randomized controlled trials (RCTs) included in our meta-analysis on safety of exercise training (ET) in MS. We adopted definitions and metrics of adherence and compliance provided by the MoXFo adherence group. Drop-out was reported in 100% of the RCTs and approximated 10% for intervention and control conditions. Adherence and compliance were reported in approximately 50% and 10% of the RCTs, respectively, and approximated 80% and 70%, respectively. Standardized metrics for reporting adherence and compliance are important in future RCTs for understanding the impact on outcomes and translation of research evidence into practice.

The Compendium of Physical Activities reports that walking at 2.5 mph associates with absolutely-defined moderate intensity (i.e., ≥3 metabolic equivalents [METs]). However, it is unclear whether this speed threshold is accurate during overground walking and/or across the adult age-span. This study aimed to identify optimal and heuristic speed thresholds associated with 3 METs during overground walking across age groups. Healthy adults (n = 248, 21–85 years old, 49% women) performed a 5-minute self-paced overground walking trial. Speed was measured using an electronic gait mat, and oxygen uptake was measured using indirect calorimetry and converted to METs. Optimal and heuristic thresholds and classification accuracy metrics were determined and compared using ROC curve analyses. Speed thresholds (95% CIs) associated with 3 METs for the whole sample, young (21–40 years), middle-aged (41–60 years) and older-aged (61–85 years) groups were 1.29 (1.25, 1.33), 1.30 (1,26, 1,35), and 1.25 (1.21, 1.29) m/s, respectively. Overall, 3 mph and 5 km/h performed better than 2.5 mph and 4.5 km/h in balancing both sensitivity and specificity (higher Youden’s Indices). Overground walking speeds associated with 3 METs were similar across age groups. A heuristic threshold of 3 mph or 5 km/h may better identify absolutely-defined moderate intensity overground walking.

Background: Physical function and walking performance have become important outcomes in clinical trials and rehabilitation involving persons with multiple sclerosis (MS). However, assessments conducted in controlled settings may not reflect real-world capacity and movement in a natural environment. Peak cadence via accelerometry might represent a novel measure of walking intensity and prolonged natural effort under free-living conditions. Objective: We compared peak 30-minute cadence, peak 1-minute cadence, and time spent in incremental cadence bands between persons with MS and healthy controls, and examined the associations between peak cadence and laboratory-assessed physical function and walking performance. Methods: Participants (147 MS and 54 healthy controls) completed questionnaires on disability status and self-reported physical activity, underwent the Short Physical Performance Battery, Timed 25-Foot Walk, Timed Up and Go, and 6-Minute Walk, and wore an accelerometer for 7 days. We performed independent samples t-tests and Spearman bivariate and partial correlations adjusting for daily steps. Results: The MS sample demonstrated lower physical function and walking performance scores, daily steps, and peak cadence ( P < .001), and spent less time in purposeful steps and slow-to-brisk walking (40-119 steps/minutes), but accumulated more incidental movement (1-19 steps/minutes) than healthy controls. The associations between peak cadence and performance outcomes were strong in MS (| r_s| = 0.59-0.68) and remained significant after controlling for daily steps (| pr_s| = 0.22-0.44), P-values < .01. Peak cadence was inversely correlated with age and disability, regardless of daily steps ( P < .01). Conclusions: Our findings provide preliminary evidence for the potential use of peak cadence with step-based metrics for comprehensively evaluating free-living walking performance in MS.