Author + information
- Benno Krachler, MD, PhD, MS∗ ( and )
- Bernt Lindahl, MD, PhD
- ↵∗Behavioral Medicine, Occupational and Environmental Health unit, Department of Public Health and Clinical Medicine, Umeå University Hospital, Umeå 90185, Sweden
We read with interest the study by Pathak et al. (1) of the role of exercise in the care of obese patients with atrial fibrillation (AF). The authors demonstrated convincingly the compound benefit of an “alliance of cardiorespiratory fitness with weight-loss” in preventing recurrence of AF. We accept the validity of the main conclusion but want to point out that the fitness test used cannot discriminate between effects of fitness gain and weight loss.
As stated recently, the treadmill protocol used for estimating fitness is likely to introduce a bias against obese individuals (2). Briefly, the most accurate test of cardiorespiratory fitness is direct measurement of oxygen consumed in a maximal exercise test. The indirect treadmill test that was used in the current study is a simplified protocol for clinical use (1). As in all weight-bearing forms of exercise, obese individuals are at a disadvantage as they have to carry more weight in the form of fat that does not contribute to exercise performance. Thus, other things being equal, the more obese subjects will be exhausted earlier and their fitness estimated lower. Correction of a similar body composition bias required appreciation of fitness estimates with increasing obesity by 17% to 39% (3). In the current study, it is impossible to establish whether fitness can compensate for fatness as the measure of fitness (treadmill time) in itself is a function of both fitness and fatness.
We fully agree with the authors that both weight loss and physical exercise are essential components of risk management in overweight and obese subjects: Advocating a fitness-first approach (4), based on treadmill test results similar to those in the current study, might mislead the general public into turning a blind eye to the importance of simultanous dietary weight management.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
- Pathak R.K.,
- Elliott A.,
- Middeldorp M.E.,
- et al.
- Krachler B.