Letter to the Editor Rest heart rate and mortality: More physical exercise for the rabbit? Giuseppe Lippi a, ⁎, Fabian Sanchis-Gomar b , Gianfranco Cervellin c a Unità operativa di Diagnostica Ematochimica, Azienda Ospedaliero-Universitaria di Parma, Italy b Department of Physiology, Faculty of Medicine, University of Valencia, Spain c Unità operativa di Pronto Soccorso e Medicina d'Urgenza, Azienda Ospedaliero-Universitaria di Parma, Italy article info Article history: Received 3 July 2012 Accepted 23 August 2012 Available online xxxx Keywords: Heart rate Mortality Risk factor Health We read with interest the letter by Chrysohoou et al., who con- vincingly concluded that rest heart rate should be considered a po- tential target for pharmacologic therapies for mortality reduction, especially in high-risk patients [1]. This assumption was supported by data provided in a previous article, wherein Bemelmans et al. con- cluded that elevated rest heart rate is a significant predictor of mortality in patients with known cardiovascular disease [2]. It is noteworthy that increased rest heart rate was also found to be significantly associated with a higher risk of developing type 2 diabetes [3], as well as with a greater likelihood of cardiovascular complications and death in dia- betics [4]. The potential association between rest heart rate and mortal- ity is thereby nothing but ancillary, since the former might now be considered as a novel and “modifiable” risk factor for mortality and/or cardiovascular disease. However, a crucial question remains unclear: how can we significantly lower the rest heart rate by safe and reliable interventions? Although we would all agree on the general issue that lowering rest heart rate may be globally beneficial, what seems less obvious is the pharmacologic approach put forward by Chrysohoou et al. [1]. There are indeed several medications that can significantly lower the heart rate, including antiarrhythmics, beta-antagonists, serotonin 5-HT1 (5-hydroxytryptamine1) receptor agonists, calcium channel blockers and cardiac glycosides among others, but their use must be carefully monitored and is often associated with side effects. It is hence noteworthy that physical exercise would appear the simplest, most ancient and reasonable approach. It is now well established that endurance training significantly increases parasympathetic activ- ity and decreases sympathetic activity in the human heart at rest, thus finally lowering intrinsic and resting heart rate [5]. Even a limit- ed period of exercise, such as a 12-week running program, was prov- en effective to decrease submaximal, as well as resting heart rate in both younger and older adults [6]. As such, the provocative answer to the question whether the turtle would win the rabbit in any case, is that we should paradoxically increase the physical activity of the rabbit to increase its longevity. A recent consensus statement on health and fitness endorsed by the International Olympic Committee (IOC) emphasized that more focus should be placed on the fundamental importance of physical ac- tivity and sports for a healthy lifestyle, for improving mental, bone, cardiovascular and metabolic health, as well as for preventing obesity and cancer [7]. This suggestion is mirrored by the fact that an im- provement in cardiorespiratory fitness is associated with a lower risk of all-cause mortality [8]. Even more importantly, the recommen- dation for adults released by the American College of Sports Medicine (ACSM) and the American Heart Association (AHA) suggested that all healthy adults aged 18 to 65 years need moderate-intensity aerobic (endurance) physical activity for a minimum of 30 min on five days each week, or vigorous-intensity aerobic physical activity for a mini- mum of 20 min on three days each week [9]. More recently, these recommendations were further revised, and the ACSM now suggests moderate-intensity cardiorespiratory exercise training for not less than 150 min each week, vigorous-intensity cardiorespiratory exer- cise training for more than 75 min each week, as well as a combina- tion of moderate- and vigorous-intensity exercise to reach a total energy expenditure of not less than 500 to 1000 Metabolic Equivalent (MET)/min each week [10]. In most cases, however, these official documents were issued as- suming a proven metabolic benefit of exercise on conventional cardio- vascular risk factors, but not on the heart rate. Now, the convincing claim of Chrysohoou et al. [1], that rest heart rate may be a promising therapeutic target for improving cardiovascular health, raises the im- portant question as to whether the guidelines and recommendations about quantity and quality of exercise in both adolescents and adults should be revised to take into account the potential benefits of exercise on rest heart rate. International Journal of Cardiology xxx (2012) xxx–xxx ⁎ Corresponding author at: U.O. Diagnostica Ematochimica, Azienda Ospedaliero- Universitaria di Parma, Via Gramsci, 14, 43126, Parma, Italy. Tel.: +39 0521 703050, +39 0521 703197. E-mail addresses: glippi@ao.pr.it, ulippi@tin.it (G. Lippi). IJCA-15151; No of Pages 2 0167-5273/$ – see front matter © 2012 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2012.08.034 Contents lists available at SciVerse ScienceDirect International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard Please cite this article as: Lippi G, et al, Rest heart rate and mortality: More physical exercise for the rabbit?, Int J Cardiol (2012), http:// dx.doi.org/10.1016/j.ijcard.2012.08.034