Exploratory and confirmatory factor analyses identify three structural dimensions for measuring physical function in community-dwelling older adults

Muscle Quality and Physical Function in Men With and Without HIV

BACKGROUND

People with HIV (PWH) experience faster physical decline than those without HIV (PWoH), despite antiretroviral therapy. We compared skeletal muscle density and area and their relationship with physical function among PWH and PWoH.

METHODS

Quantitative computed tomography scans were performed at the L4-L5 spinal region and the thigh to evaluate muscle groups in Multicenter AIDS Cohort Study participants at baseline. Using exploratory factor analysis, we summarized aggregated muscle measures based on factor loadings. Longitudinal associations between muscle area and density with gait speed and grip strength were examined using multivariable linear regression models with generalized estimating equations, adjusting for demographics, HIV serostatus, and other health metrics.

RESULTS

We included 798 men (61% of PWH). The median age was 54 years (interquartile range: 49-59), 61% were White, 32% Black, and 10% Hispanic. Among them, 22% had a body mass index over 30 kg/m2, and 14% had diabetes. Two factors emerged from the factor analysis explaining 55.9% of variance. Factor 1 (explained 32.5% of variance) encompassed all density measures. Factor 2 (explained 23.4% of variance) encompassed all area measures. Associations between muscle density and gait speed were more pronounced with aggregated measures than with individual ones. Specifically, each unit increase in overall muscle density correlated with a 0.028 m/s increase in gait speed (95% confidence interval [CI]: 0.017, 0.038, p < .01). Grip strength was associated with aggregated measures of both muscle density and area, with overall muscle density associated with a 1.88 kg increase in grip strength (95% CI: 1.29, 2.46, p < .01), and overall muscle area with a 1.60 kg increase (95% CI: 1.02, 2.19, p < .01).

CONCLUSIONS

Aggregated muscle density and area measurements were significantly associated with physical function. These correlations underscore the importance of interventions to enhance skeletal muscle to improve healthy aging for PWH and PWoH.

Acquisition and Retention Effects of Fundamental Movement Skills on Physical Activity and Health-Related Fitness of Children with Autism Spectrum Disorder

This study adopted a quasi-experimental design to explore the effects of fundamental movement skill intervention on the acquisition and retention of physical activity levels and health-related fitness in children with autism spectrum disorder (ASD). In the experiments, 11 children received fundamental motor skill training (12 weeks, 60 min/session, 4 times/week), and 10 children maintained traditional physical activity. Assessments were performed using an ActiGraph GT3X+ accelerometer, health-related fitness pre-post intervention, and 1-month follow-up tests. The sedentary time during physical activity was significantly decreased (p = 0.01), and there were large changes in health-related physical fitness indicators, including significantly improved body composition (body mass index, F(1,19) = 8.631, p = 0.03, partial η2 = 0.312), muscle strength and endurance (sit-ups, F(1,19) = 3.376, p = 0.02, partial η2 = 0.151 and vertical jumps, F(1,19) = 5.309, p = 0.04, partial η2 = 0.218), and flexibility (sit and reach, F(1,19) = 36.228, p = 0.02, partial η2 = 0.656). Moreover, the follow-up tests showed that the children's sedentary time continued to reduce, and the muscle strength and endurance (sit-ups, F(1,19) = 4.215, p = 0.01, partial η2 = 0.426) improved continuously after the intervention. Based on this study, actionable and regular fundamental movement skill programs can be provided in the future as an effective way to achieve the healthy development goals of children with ASD.

Responsiveness of Isokinetic Dynamometry in Patients with Osteoarthritis after Knee and Hip Arthroplasty: A Prospective Repeated-Measures Cohort Study

Functional assessments are crucial for the evaluation of rehabilitation after total knee (TKA) and hip (THA) arthroplasty. Muscle strength, a key determinant of physical function (PF), is often measured with isokinetic dynamometry (ID), which is considered the gold standard. However, studies lack evaluations of responsiveness-the ability to detect changes over time. This study aims to determine the responsiveness of ID in measuring PF in TKA and THA rehabilitation-is muscle strength a valid indicator for assessing improvement in rehabilitation processes? The pre- and post-surgery PF of 20 osteoarthritis patients (age 55-82) was assessed, using ID, performance-based and self-reported measures. Responsiveness was evaluated by comparing the observed relationship of changes in ID and PF scores with the a priori defined expected relationship of change scores. While the performance-based and self-reported measures showed significant improvements post-surgery (Cohen's d [0.42, 1.05] p < 0.05), ID showed no significant differences. Moderate correlations were found between changes in some ID parameters and selected functional tests (r ≈|0.5|, p < 0.05). Responsiveness was solely found for the peak torque of knee extension at 180°/s on the operated side. Responsiveness is an often-overlooked psychometric property of outcome measurements. The findings suggest that ID may not be fully responsive to the construct of PF after TKA and THA, raising questions about its role and usefulness in this context and the need for more appropriate assessment methods.