Introduction: The normative values of exercise capacity used for the interpretation of exercise testing results are influenced by a variety of internal and external factors specific to certain populations. Therefore, in clinical practice it is recommended that population-specific reference values be employed. Cardiorespiratory fitness norms have not yet been established for a healthy Lithuanian population over a wide age span. The purpose of the present study was to determine the main cardiorespiratory fitness parameters for healthy adults living in Lithuania and to compare these parameters with the reference values established for different foreign populations.
Methods: This was a cross-sectional, community-based study involving 168 healthy adults aged from 20 to 60 years who were randomly selected from the general population. All subjects performed a progressive incremental exercise test on the cycle ergometer. The main cardiorespiratory fitness parameters analysed were peak oxygen consumption (VO2peak), ventilatory anaerobic threshold, and peak heart rate (HRpeak).
Results: The average estimated VO2peak was 35.02 ± 7.37 mL.kg(-1).min(-1) for men and 28.27 ± 6.33 mL.kg(-1).min(-1) for women. According to the results presented by other authors, this parameter is approximately 9-22% lower compared to other populations in all age groups, with the exception of the 20-29 year old group who alone satisfied fair aerobic fitness criteria. The average age-related decline in VO2peak was 0.016 L.min(-1) per year for men and 0.011 L.min(-1) per year for women. However, age itself explained only 12-14% of the variance. After VO2peak was adjusted relative to body mass, the difference in the decline between men and women remained insignificant: VO2peak decrease was 0.34 mL.kg(-1).min(-1) per year for men (coefficient of determination R(2) 0.250) and 0.32 mL.kg(-1).min(-1) per year for women (R(2) 0.330). A decline in peak heart rate of approximately 9 beats per minute was observed in each following age decade, which was well explained by the advancing age (R(2) 0.512 for men and R(2) 0.484 for women).
Conclusions: Cardiorespiratory fitness parameters estimated for healthy adults living in Lithuania appeared to be lower compared to different foreign populations, despite the relatively similar general trends in the age-related decline in exercise capacity. Exercise testing laboratories and rehabilitation clinics in Lithuania may use these results in clinical practice when evaluating patients' exercise capacity, or as a promotional tool for physical activity in the general public.