Author + information
- Patricia Palau, MD, PhD∗ (, )
- Antoni Bayés-Genís, MD, PhD and
- Julio Núñez, MD, PhD
- ↵∗Cardiology Department, Hospital General Universitario de Castellón, Universitat Jaume I, Avda. Benicasim, s/n, 12004, Castellón-Spain
Clausen et al. (1) report on the prognostic role of midlife physical fitness on long-term prediction of cardiovascular mortality and all-cause mortality in a prospective cohort of asymptomatic Danish population. Given the decline in physical activity among young adults in Western countries throughout the last decades (2), these positive results are greatly appreciated and may be envisioned as an excellent starting point for further research lines aiming to improve cardiorespiratory fitness among the middle-aged population.
This work (1) remarks on the utility of physical fitness in midlife as a useful tool for risk stratification using a single parameter: heart rate during a submaximal cycle ergometer exercise test. The authors estimated the maximal aerobic capacity (Vo2max) based on the Åstrand et al. (3) monogram with no measurement of gas exchange parameters. Even though the results showed a robust association between long-term prognosis and physical fitness in midlife, there are some issues that deserve to be commented on for avoiding misconception and improving generalizability of these findings.
First, Vo2max estimated in the present study is based on results from experiments in the 1950s with young healthy subjects, 18 to 30 years old (3), but these results have not been validated in older subjects. Second, in the Åstrand et al. (3) monogram the best results were obtained when the heart rate during the steady state of exercise test was between 125 and 170 beats/min. Thus, the accuracy of Vo2max estimation below or above these values of heart rate is more conflicting.
Third, all participants were interviewed by a physician excluding history of cardiovascular disease. Unfortunately, there were no data about musculoskeletal condition, respiratory disease, or other disorder in the oxygen-transporting system. Once again, we must consider that the Åstrand et al. (3) monogram excluded all these comorbidities. Lastly, despite the authors adjusted risk estimations for age and categories of body mass index among other covariates, we believe that evaluating Vo2max as a percentage of age-, body mass index–, and sex-predicted Vo2max equations may infer with more accuracy the contribution of physical fitness in prognosis.
In conclusion, we acknowledged the relevance of these findings for clinical practice, yet in-depth analysis of the beneficial role of physical activity in young adults is warranted. Additionally, further studies evaluating the contribution of physical fitness for predicting adverse events in women are welcome.
Please note: All authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2018 American College of Cardiology Foundation