Adiposity and grip strength: a Mendelian randomisation study in UK Biobank

Area of Science:

• Gerontology
• Metabolic Health
• Musculoskeletal Health

Background:

• Muscle weakness is a growing concern with age, impacting public health.
• Grip strength is a key indicator of muscle weakness, necessitating a deeper understanding of its determinants.
• Adiposity, encompassing total and central fat, is a potential factor influencing grip strength.

Purpose of the Study:

• To investigate the causal associations between various adiposity indicators and grip strength.
• To explore sex-specific relationships between adiposity and grip strength.
• To examine how age influences the association between adiposity and grip strength.

Main Methods:

• Utilized data from up to 470,786 UK Biobank participants (aged 38-73).
• Assessed four adiposity indicators: body mass index (BMI), body fat percentage (BF%), waist circumference (WC), and waist-hip-ratio (WHR).
• Employed Mendelian randomization (MR) and observational analyses, including age-stratified examinations.

Main Results:

• In males, higher BMI and WC correlated with stronger grip, while higher BF% and WHR correlated with weaker grip.
• In females, higher BF% was linked to weaker grip, and higher WC to stronger grip; other associations were inconsistent.
• The association of BMI and WC with grip strength was weaker in older males.

Conclusions:

• Findings suggest causal links between adiposity and grip strength, supporting evidence triangulation.
• Higher body fat percentage is causally associated with weaker grip strength in both sexes.
• Higher waist-hip-ratio is causally associated with weaker grip strength in males.