Simple method for measurement of lower extremity muscle strength

Area of Science:

• Gerontology
• Neurology
• Physical Therapy

Background:

• Quantifying lower extremity muscle strength is crucial for assessing functional decline and disease progression.
• Existing methods may be time-consuming or require specialized equipment.
• A simple, reproducible measure is needed for clinical and research settings.

Purpose of the Study:

• To standardize and validate a simple, rapid method for quantifying lower extremity muscle strength.
• To investigate the relationship between age, sex, and muscle strength using this method.
• To assess the utility of this method in monitoring disease progression and treatment response in patients with inflammatory myopathies.

Main Methods:

• A cohort of 139 healthy individuals (20-85 years) performed 10 chair stands, with time recorded.
• Reproducibility was assessed.
• Statistical analyses examined relationships between time, age, height, and weight.
• The method was applied to six patients with polymyositis or dermatomyositis undergoing treatment.

Main Results:

• The chair stand test demonstrated good reproducibility (6.8%).
• Age was a highly significant predictor of performance (p < 0.0001), with strength declining significantly with age.
• While younger men outperformed younger women, this difference diminished in older age groups.
• Weight showed a slight correlation with time after adjusting for age.
• The test results correlated well with established measures of knee muscle strength.
• All six myositis patients showed improvement in muscle strength after treatment.

Conclusions:

• The 10-time chair stand test is a simple, rapid, and reproducible method for assessing lower extremity muscle strength.
• Muscle strength significantly declines with age in both sexes, with sex-based differences diminishing in older adults.
• This method is a valuable tool for evaluating muscle strength in healthy aging populations and for monitoring treatment efficacy in inflammatory myopathies.