Perinatal HIV infection is associated with deficits in muscle function in children and adolescents in Zimbabwe.

OBJECTIVES: To determine how muscle strength, power, mass, and density (i.e. quality) differ between children living with HIV (CWH) and those uninfected, and whether antiretroviral therapy (ART) regime is associated with muscle quality. DESIGN: A cross-sectional study in Harare, Zimbabwe. METHODS: The study recruited CWH aged 8-16 years, taking ART for at least 2 years, from HIV clinics, and HIV-uninfected children from local schools. Muscle outcomes comprised grip strength measured by hand-held Jamar dynamometer, lower limb power measured by standing long-jump distance, lean mass measured by dual-energy X-ray absorptiometry, and muscle density (reflecting intramuscular fat) by peripheral quantitative computed tomography. Linear regression calculated adjusted mean differences (aMD) by HIV status. RESULTS: Overall, 303 CWH and 306 without HIV, had mean (SD) age 12.5 (2.5) years, BMI 17.5 (2.8), with 50% girls. Height and fat mass were lower in CWH, mean differences (SE) 7.4 (1.1) cm and 2.7 (0.4)kgs, respectively. Male CWH had lower grip strength [aMD 2.5 (1.1-3.9) kg, P  < 0.001], long-jump distance [7.1 (1.8-12.5) cm, P  = 0.006], muscle density [0.58 (0.12-1.05) mg/cm 3 , P  = 0.018, but not lean mass 0.06 (-1.08 to 1.21) kg, P  = 0.891) versus boys without HIV; differences were consistent but smaller in girls. Mediation analysis suggested the negative effect of HIV on jumping power in boys was partially mediated by muscle density ( P  = 0.032). CWH taking tenofovir disoproxil fumarate (TDF) had lower muscle density [0.56 (0.00-1.13)mg/cm 3 , P  = 0.049] independent of fat mass, than CWH on other ART. CONCLUSION: Perinatally acquired HIV is associated, particularly in male individuals, with reduced upper and lower limb muscle function, not mass. Intra-muscular fat (poorer muscle quality) partially explained reductions in lower limb function. TDF is a novel risk factor for impaired muscle quality.

Wearable GPS and Accelerometer Technologies for Monitoring Mobility and Physical Activity in Neurodegenerative Disorders: A Systematic Review.

Neurodegenerative disorders (NDDs) constitute an increasing global burden and can significantly impair an individual's mobility, physical activity (PA), and independence. Remote monitoring has been difficult without relying on diaries/questionnaires which are more challenging for people with dementia to complete. Wearable global positioning system (GPS) sensors and accelerometers present a cost-effective and noninvasive way to passively monitor mobility and PA. In addition, changes in sensor-derived outcomes (such as walking behaviour, sedentary, and active activity) may serve as potential biomarkers of disease onset, progression, and response to treatment. We performed a systematic search across four databases to identify papers published within the past 5 years, in which wearable GPS or accelerometers were used to monitor mobility or PA in patients with common NDDs (Parkinson's disease, Alzheimer's disease, motor neuron diseases/amyotrophic lateral sclerosis, vascular parkinsonism, and vascular dementia). Disease and technology-specific vocabulary were searched singly, and then in combination, identifying 4985 papers. Following deduplication, we screened 3115 papers and retained 28 studies following a full text review. One study used wearable GPS and accelerometers, while 27 studies used solely accelerometers in NDDs. GPS-derived measures had been validated against current gold standard measures in one Parkinson's cohort, suggesting that the technology may be applicable to other NDDs. In contrast, accelerometers are widely utilised in NDDs and have been operationalised in well-designed clinical trials.