Functional fitness and physical independence in later years: cut-off values and validation

To establish and validate the criterion-referenced standards of functional fitness in predicting physical independence in 80 + years. A group of 2,749 older community dwellers (60–84 years) were recruited, and 2,050 were identified with moderate-to-high independent living ability according to the proposed minimum composite physical function score. The Senior Fitness Test battery was applied to measure functional fitness at five-year intervals. The declining rate for each fitness dimension was calculated based on the differences between any two adjacent age groups and was adjusted according to the reported degradation rate differences between the cross-sectional and longitudinal studies. The age-and-sex-specific criterion-referenced standards were identified for muscle strength, cardiovascular endurance, and dynamic balance that older adults should possess at 60–79 to maintain independent living abilities. Moderate to high consistency (k = 0.622–0.650) and associations (φ = 0.641–0.694) were found between the predicted physical independence by criterion-referenced standards of functional fitness and the results from the composite physical function scale. Moreover, the predicted independent living abilities in later years from the criterion-referenced standards of functional fitness showed high test-retest reliability (Pa = 0.90–0.96). The criterion-referenced standards for functional fitness are valid and reliable to predict independent living abilities in later years, and provide the threshold to identify the limitations in physical fitness and detect the risks of functional disabilities among older adults in an early stage.