Physical function and physical activity in adults with X-linked hypophosphatemia

Area of Science:

• Orthopedics and Musculoskeletal Diseases
• Genetics and Genetic Diseases
• Metabolic Diseases

Background:

• Limited research exists on the physical function and activity levels of adults with X-linked hypophosphatemia (XLH).
• This study aimed to describe muscle strength, power, functional capacity, mobility, and physical activity in adults with XLH.
• The study also explored the interrelationships among these physical parameters in the XLH population.

Purpose of the Study:

• To characterize physical function and activity in UK adults diagnosed with X-linked hypophosphatemia (XLH).
• To investigate the prevalence of impaired mobility and low physical activity in this patient group.
• To identify potential contributing factors to the loss of physical function in adults with XLH.

Main Methods:

• A prospective cohort study (the RUDY Study) recruited 26 adults with XLH from the UK.
• Assessments included handgrip strength, jump power (mechanography), the six-minute walk test (6MWT), and the Short Physical Performance Battery (SPPB).
• The International Physical Activity Questionnaire (IPAQ) was used to measure physical activity levels, with data analyzed using parametric/non-parametric tests and univariate correlation analysis.

Main Results:

• Adults with XLH exhibited significantly lower jump power (54.4% deficit) and 6MWT distances (38.6% deficit) compared to normative values.
• Deficits in lower limb muscle power were more pronounced than functional capacity limitations.
• A significant positive correlation was found between total physical activity and muscle power (r=0.545, p=0.019).

Conclusions:

• Adults with XLH demonstrate substantial deficits in lower limb muscle power and functional capacity, alongside high rates of impaired mobility and physical inactivity.
• Reduced physical activity may exacerbate the muscle power deficits observed in XLH, beyond the direct metabolic effects of the condition.
• Further research is warranted to develop innovative therapeutic strategies aimed at enhancing physical function and mobility in individuals with XLH.