Abstract
Background: Although the level of cardiorespiratory fitness (CRF) in older adults has been well documented, little evidence has been provided regarding sex- and age-specific reference standards. Therefore, the main purpose of the study was to examine objectively measured CRF in older adults based on sex and age. Methods: This observational study included 450 men (N = 170) and women (N = 280) aged ≥60 years with mean ± standard deviation (SD) for age (67.4 ± 5.4), height (165.7 ± 8.6 cm), weight (75.1 ± 13.3 kg) and body mass index (BMI, 27.1 ± 3.9 kg/m(2)). Participants performed an incremental exercise ramp test until exhaustion on a treadmill, and the outcome of CRF was presented as peak oxygen uptake (VO(2peak)) in milliliters per kilogram of body mass per minute (ml/kg/min). Results: Relative VO(2peak) values were 37.3 ± 7.1, 30.3 ± 6.6, 24.8 ± 5.4 and 21.7 ± 5.8 mL/kg/min for men aged 60-64 years, 65-69 years, 70-74 years and ≥75 years. For the same age groups in women, values were 30.5 ± 4.8, 27.1 ± 5.4, 22.4 ± 3.4 and 18.9 ± 4.7 mL/kg/min. Age-related declines were observed in both men and women (p < 0.001). In a sex-age interaction term, significant main effects occurred, where men in every age group exhibited higher VO(2peak) values, compared to women in the same age groups. Conclusions: This study shows that CRF needs to be assessed by considering sex and age as significant predictors. Thus, sex- and age-specific reference findings may serve as an avenue to monitor, track and compare between older adults of different nationalities.