Reference values for developing responsive functional outcome measures across the lifespan

Objective: To generate a reference dataset of commonly performed functional outcome measures in 1,000 children and adults and investigate the influence of demographic, anthropometric, strength, and flexibility characteristics. Methods: Twelve functional outcome measures were collected from 1,000 healthy individuals aged 3-101 years: 6-minute walk test, 30-second chair stand test, timed stairs test, long jump, vertical jump, choice stepping reaction time, balance (Star Excursion Balance Test, tandem stance eyes open and closed, single-leg stance eyes closed), and dexterity (9-hole peg test, Functional Dexterity Test). Correlation and multiple regression analyses were performed to identify factors independently associated with each measure. Results: Age-and sex-stratified reference values for functional outcome measures were generated. Functional performance increased through childhood and adolescence, plateaued during adulthood, and declined in older adulthood. While balance did not differ between the sexes, male participants generally performed better at gross motor tasks while female participants performed better at dexterous tasks. Height was the most consistent correlate of functional performance in children, while lower limb muscle strength was a major determinant in adolescents and adults. In older adults, age, lower limb strength, and joint flexibility explained up to 63% of the variance in functional measures. Conclusions: These normative reference values provide a framework to accurately track functional decline associated with neuromuscular disorders and assist development and validation of responsive outcome measures for therapeutic trials.