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Canadian Journal of Cardiology

Canadian Physical Activity Clinical Practice Guidelines: Running on Empty?

Published:March 16, 2016DOI:https://doi.org/10.1016/j.cjca.2016.01.037
      There is a line in the 1977 Jackson Browne song Running on Empty that says,
      “…You know I don't even know what I'm hoping to find, running blind….” The apparent origins of the song refer to when the artist was recording his gold record album The Pretender and he was constantly driving his car on empty because he never seemed to have time to fill it up. He reasoned that with a gas station every few blocks, he could always fill up. Presumably, at some point in time, this strategy invariably failed, thereby demonstrating that running on empty may very well be analogous to running blind.
      In the derivation and development of contemporary evidence-informed clinical practice guidelines (CPGs), every expert panel and stakeholder group very much wants to avoid running on empty, ie, deriving clinical practice recommendations in the absence of clearly linked high-quality scientific evidence. Similarly, CPG groups need to avoid running blind and empty by regularly and consistently updating the evidence base used to produce clinical practice recommendations. However, as in many aspects of life, what people hope to achieve is not always consistent with the path that they are taking to achieve their desired destination. As stated succinctly by the Cheshire cat in Alice in Wonderland, “If you don't know where you're going, any road will get you there,” ie, running blind. For historically remote CPGs from the previous century, this meant that without a clear evidence base, almost any CPG could be deemed a relevant road to the improvement of clinical outcomes. At that time, given this relative paucity of high-quality scientific evidence, CPGs were developed mostly by clinicians who simply formalized their collective personal opinions regarding clinical practice and published them as a guideline, ie, CPGs running on empty. Not surprisingly, other expert clinicians who were not part of this CPG development process simply rejected these consensus recommendations. Indeed, in Canada in 1997, CPGs based mostly on expert consensus opinion were infrequently followed or implemented in clinical practice.
      • Davis D.A.
      • Taylor-Valsey A.
      Translating clinical guidelines into practice.
      Fast forward 20 years and even a cursory look at the clinical practice environment today reveals hundreds of evidence-informed CPGs for numerous acute and chronic disease conditions. In most aspects of medical practice, CPGs have become an essential clinical tool. Yet, as they have become more ubiquitous, their development and derivation have become increasingly complex. None of us, no matter how dedicated or diligent, can keep up with everything that is in the medical and scientific literature. Even more pertinent is the reality that very few clinicians who spend the vast majority of their time looking after patients on a day-to-day basis have the necessary background and training to make difficult analytical decisions about the quality and relevance of the published scientific evidence. Time was when a P value told you pretty much everything you wanted to know about a clinical trial. Today, vigorous debate about the results of clinical trials often centres around statistical vagaries, the applicability of the patient populations studied to one's particular practice environment, the importance of baseline risk in those populations for any particular outcome or event, the essential discussions around risk to benefit, the appropriateness of the therapeutic interventions, and the number of patients needed to both treat and harm when trying to achieve improved outcomes. With this level of complexity, many of us are frequently running blind.
      Canadian cardiovascular CPGs, including physical activity and exercise, are some of the most intensively researched and resourced CPGs in the world.
      • Tobe S.W.
      • Stone J.A.
      • Walker K.M.
      • et al.
      Canadian Cardiovascular Harmonized National Guidelines Endeavor (C-CHANGE): 2014 update.
      These particular CPG development panels contain members from all the health care professions, and increasingly patient groups, who have expertise in clinical care, statistics, clinical epidemiology, health behaviour interventions, and pharmacologic or device therapies. This vast diversity of expertise results in the production of evidence-informed clinical practice recommendations that closely adhere to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) recommendations for assessing the quality of medical evidence as well as the Appraisal of Guidelines for Research and Evaluation (AGREE) appraisal tool for determining the quality of clinical practice guidelines.
      • Guyatt G.H.
      • Oxman A.D.
      • Vist G.
      • et al.
      Rating quality of evidence and strength of recommendations GRADE: an emerging consensus on rating quality of evidence and strength of recommendations.
      • Brouwers M.C.
      • Kho M.E.
      • Browman G.P.
      • et al.
      AGREE II: advancing guideline development, reporting and evaluation and healthcare.
      To be certain, in those areas of medical practice in which high-quality evidence is lacking, CPGs may still contain mostly expert consensus opinion. However, almost uniformly in the field of cardiovascular medicine, contemporary CPGs represent the safest, most robust, and most clinically effective manner in which to manage and advise patients.
      In this issue of the Canadian Journal of Cardiology, Dr Darren Warburton and his colleague Dr Shannon Bredin present a very comprehensive and provocative review of contemporary physical activity and exercise guidelines.
      • Warburton D.E.R.
      • Bredin S.S.D.
      Reflections on physical activity and health: what should we recommend?.
      The expressed purpose of their review was to undertake a very directed look at the relationship between the dose of physical activity and exercise obtained by individuals—derived from the frequency, intensity, duration, and type of physical activity and exercise performed—and their subsequent health outcomes. At the present time, the vast majority of physical activity and exercise clinical practice guidelines around the world, including the Canadian Physical Activity Guidelines,

      Canadian Society For Exercise Physiology. Canadian Physical Activity Guidelines. Available at: http://www.csep.ca/CMFiles/Guidelines/CSEP_PAGuidelines_adults_en.pdf. Accessed January 8, 2016.

      recommend that adults aged 18-65 years and older accumulate 150 minutes of moderate to vigorous physical activity per week. The scientific evidence base on which this treatment target was based strongly suggests improved outcomes for a number of chronic disease conditions and a possible maintenance or attenuated temporal reduction in functional capacity. Importantly, Warburton and Bredin correctly point out that there is a clinically relevant difference between physical activity, a health behaviour, and physical fitness or functional capacity, which is an objective assessment. To those outside the exercise and physical activity communities, this distinction may seem somewhat arcane. However, it is key to understanding the dose-response relationship between physical activity, exercise, and health outcomes. As pointed out by the authors, the relationship between physical fitness, the objective assessment of a physical state, and health outcomes such as mortality is much more closely related than the association between physical activity and similar health outcomes. The reason for this is quite simple. As an objective measure of a physical state, physical fitness is not arbitrary. Conversely, because physical activity is for the most part a subjective assessment reported by individuals, what individuals report as their usual dose of physical activity may be significantly different from what they actually do. In the future, the use of personalized digital devices that carefully measure physical activity, as well as genetic studies regarding the relationship between physical activity and functional capacity, may help to better inform us about this relationship. Currently and historically, however, researchers assessing physical activity and attempting to determine its effect on health outcomes are routinely faced with numerous confounders in carefully documenting a person's or populations' true dose of physical activity.
      Physical activity and exercise CPGs around the world, including Canada, have been developed with an evidence database that includes randomized clinical trials and epidemiologic studies. Within the GRADE evidence assessment algorithm, well-performed, well-controlled randomized clinical trials may be rated as higher-quality evidence compared with even extremely large epidemiologic studies. As a direct result of this reality, CPG developers must be cognizant of the veracity of the information at their disposal when developing evidence-informed clinical practice recommendations. Strong clinical practice recommendations based on high-quality evidence from a small number of study participants may be preferable to relatively weak clinical practice recommendations derived from less reliable scientific information, even in very large study populations. In addition to this challenge, CPG developers, and critiques, need to be mindful of the fact that when assessing a subjective health behaviour such as physical activity within a large epidemiologic study, what qualifies as vigorous physical activity in one culture may be viewed as only a moderate level of physical activity in another culture. Under these circumstances, the culture with moderate physical activity may obtain substantial health benefits simply because their perceived levels of physical activity are, in fact, considerably different.
      The essential thesis of Drs Warburton and Bredin is that the contemporary physical activity and exercise CPGs around the world may significantly overestimate the dose of physical activity required to obtain clinically meaningful and beneficial health outcomes. Through a careful up-to-date examination of the scientific literature, they construct a persuasive argument indicating that engaging in weekly doses of physical activity that are significantly less than currently recommended levels may still produce substantial health outcomes. This conclusion is not a surprise to the exercise communities. It has long been known that the ability to successfully increase an individual's physical fitness, from both an absolute and relative perspective, is directly dependent on their baseline level of physical fitness. Those persons who are very unfit may obtain large increases in physical fitness with relatively modest doses of physical activity and exercise. Conversely, individuals who are already extremely fit may realize relatively paltry increases in physical fitness and functional capacity, even with extreme doses of physical activity and exercise. Accordingly, are the present physical activity and exercise guidelines wrong? Are they running on empty or is there simply a disconnect between the current messaging, intended to promote guideline implementation, and the evidence used to derive the clinical practice recommendations on which those implementation messages are based?
      As once famously stated by the renowned economist John Maynard Keynes, “When the facts change, I change my mind.” In their review article, Drs Warburton and Bredin are arguing for a significant change to the existing physical activity clinical practice guidelines. Their arguments are based on reasonable inferences drawn from state-of-the-art scientific information. However, much of the pertinent information they reference in their review article has only been published in the past few years, and some of it is based on large epidemiologic studies in which the available information may be less rigorously researched. Indeed, in 2010, Dr Warburton wrote, “Overall, the current literature supports clearly the dose-response relationship between physical activity and the seven chronic conditions identified. Moreover, higher levels of physical activity reduce the risk for premature all-cause mortality. The current Canadian guidelines appear to be appropriate to reduce the risk for the seven chronic conditions identified above and all-cause mortality.”
      • Warburton D.E.
      • Charlesworth S.
      • Ivey A.
      • et al.
      A systematic review of the evidence for Canada's Physical Activity Guidelines for Adults.
      Have Drs Warburton and Bredin now decided to change their minds? Have the facts really changed? The argument that a lesser dose of physical activity and exercise can still return significant health benefits needs to be vetted and incorporated into evidence-informed CPGs. Simply, Drs Warburton and Bredin are challenging physical activity and exercise guideline development groups to update their evidence and their recommendations. Most contemporary CPGs in medicine, particularly those dealing with large volumes of scientific data and clinically challenging situations, are revamped approximately every 5 years. In exceptional circumstances, such as the Canadian Hypertension Education Program, a process has been developed to allow yearly updates. However, this is very much the exception rather than the rule. Most CPG groups simply require more time and reflection to develop safe robust clinical practice recommendations.
      Two other clinical points from a myriad of other important arguments advanced in this review deserve to be mentioned. First, the improvements in health outcomes and hard clinical end points in cardiovascular medicine achieved through engaging in the CPG-recommended amounts of physical activity and exercise are very similar to those achieved with medications such as statin drugs, antihypertensive medications, and antiplatelet agents. Cardiovascular practitioners need to understand this. Second, as identified in this review, high-intensity physical activity and exercise performed for unusually prolonged periods may actually result in harm.
      • O’Keefe J.H.
      • Patil H.R.
      • Lavie C.J.
      • et al.
      Potential adverse cardiovascular effects from excessive endurance exercise.
      In reality, the relationship between health outcomes and the dose of physical activity and exercise may be very similar to those for other medical interventions in that there likely exists a so-called U-shaped curve. Something is frequently better than nothing. However, more—especially a great deal more—is not always better.
      The time has come to update the message regarding physical activity and exercise. However, practice implementation messages are not the same as evidence-informed clinical practice recommendations derived from high-quality evidence. More specifically, the message that some physical activity is better than none needs to be researched and validated so that it can be incorporated into CPGs. So, are current PA CPGs running on empty? Are they running blind? Clearly, the correct historical answer is an emphatic “no.” However, with rapidly emerging evidence, we need to expeditiously change all CPGs when the facts change.

      Disclosures

      The author has no conflicts of interest to disclose.

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      Linked Article

      • Reflections on Physical Activity and Health: What Should We Recommend?
        Canadian Journal of CardiologyVol. 32Issue 4
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          The health benefits of regular physical activity are irrefutable; virtually everyone can benefit from being active. The evidence is overwhelming with risk reductions of at least 20%-30% for more than 25 chronic medical conditions and premature mortality. Even higher risk reductions (ie, ≥ 50%) are observed when objective measures of physical fitness are taken. International physical activity guidelines generally recommend 150 minutes per week of moderate- to vigorous-intensity physical activity.
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