Adapting Fitness Age Calculations to Suit a Modern North American Female Population, Regardless of Age, Race, or Ability Level.

Fitness Age (FA) has been reported in Japan and South Korea as one way to assess an individual's overall health. To date, this method has not been used in North America. The objective of the current study was to assess the applicability of existing Fitness Age calculations for North American women. Thirty-seven North American working women aged 18 to 67 years completed a fitness test battery, as described by previous studies. The fitness test results were used with published regression equations to estimate each woman's FA which was subsequently adjusted to correct for biases in the data. The data from the fitness tests were similar to those presented in the previously published literature with the exception of grip strength, trunk flexion, and body fat percentage which differed significantly compared to the populations assessed previously. These population differences appear to have impacted the applicability of the published methods for this population. Because the FA estimates must be corrected according to a theoretical "ideal" to address population biases before they can be used, the authors propose using the deviation from this theoretical ideal rather than raw FA in future aging studies, as this is where the interesting inter-personal differences lay.