Corresponding Author: Marni Armstrong, PhD, University of Pittsburgh, Department of Epidemiology, Graduate School of Public Health, Diabetes Prevention Support Centre, 3512 Fifth Avenue, 3rd Floor, Pittsburgh, PA 15213, P: 412-383-1453 F: 412-383-1974, moc.liamg@gnortsmra.inram
Behavioral lifestyle interventions in the community setting are effective in reducing the risk and burden of chronic diseases. The promotion and implementation of physical activity plays a key role in these community-based lifestyle programs. New guidelines on preparticipation screening for cardiovascular disease prior to physical activity have been released which include substantive modifications. These updated recommendations represent a substantial paradigm shift toward a more liberal approach that results in fewer individuals needing to seek medical clearance before starting a physical activity program. This shift has significant implications for those promoting physical activity within the community setting. The objectives of this commentary are to review the updated recommendations within the context of community-based lifestyle intervention programs such as those currently being offered throughout the United States for the primary purpose of diabetes prevention and to discuss the implications for those providers developing and implementing such programs.
Keywords: Preparticipation screening, Physical activity, Diabetes prevention, Lifestyle InterventionAddressing the pandemic of physical inactivity is an important public health priority with targeted efforts needed across all populations (1, 2). The national Diabetes Prevention Program (DPP) (3) and subsequent translation studies have demonstrated the efficacy of behavioral lifestyle interventions in reducing the risk and burden of diabetes and other chronic diseases. Accordingly, behavioral lifestyle interventions that include physical activity promotion have expanded beyond the realm of structured, medically-supervised settings and into a variety of diverse community settings. However, the translation from the clinical setting into that of the community poses new challenges. Appropriate guidelines for physical activity preparticipation screening are important for community translation prevention efforts to help mitigate the risks associated with increased physical activity, structured exercise, or both, and to help identify individuals who may be at risk for exertion-related sudden cardiac death and/or acute myocardial infarction.
Lifestyle interventions that include the goal to increase physical activity have been shown to reduce risk factors for metabolic and cardiovascular disease (CVD) and to decrease the incidence of diabetes (4–6). The multi-centered DPP (3) was a landmark study in that it validated the use of lifestyle interventions in disease prevention, demonstrating that a behavioral lifestyle program aimed at modest weight loss and regular physical activity significantly reduced the risk of type 2 diabetes by 58% in ‘at risk’ overweight participants. The structured lifestyle intervention included a weight loss goal of >7% and a physical activity goal of >150 minutes/week of moderate physical activity with most participants performing brisk walking.
Translational research efforts since have focused on adapting the DPP lifestyle intervention into diverse settings such as local community centers (7–10), YMCAs (11–13), churches (14), worksite (15), military, and health care settings (16–18). Both systematic reviews and meta-analysis on these pragmatic translation efforts have been promising (19–22). As a result, the call to disseminate and implement DPP-based behavioral lifestyle intervention programs in real-world settings is high (23, 24). Accordingly, the Center for Disease Control (CDC) has led an initiative where programs that are based on the DPP and meet the standards of recognition can apply for accreditation through the “CDC Diabetes Prevention Recognition Program” (25, 26). Addressing the issue of preparticipation CVD screening for physical activity as part of these behavioral lifestyle programs is important in their implementation. However, the CDC Standards of Practice are not clear on this matter and simply state that “it is the organization’s responsibility to have procedures in place to assure safety” (27). Although several of the CDC recognized diabetes prevention programs currently mandate physician approval prior to participation in physical activity, the logistics of this requirement can impose barriers to participation in terms of feasibility, efficiency and cost.
The American College of Sports Medicine (ACSM), which is the preeminent professional organization for exercise science within health and medical fields, has invariably provided guidance on exercise screening for individuals planning to initiate a moderate-to-vigorous physical activity program that apply to varied settings and contexts. Recently, the ACSM released new guidelines (28) that included substantive modifications for preparticipation CVD screening for physical activity. These updated recommendations represent a substantial paradigm shift from past iterations toward a more liberal approach that results in fewer individuals needing to seek medical clearance before starting a physical activity program. This shift has significant implications for those promoting physical activity within the community setting. The objectives of this commentary are to review the new recommendations within the context of community-based diabetes prevention programs and to discuss the implications for those providers implementing and leading community-based physical activity interventions.
Out with the old
Historically, the ACSM guidelines (29) recommended that preparticipation screening for exercise be largely based on risk stratification for CVD (i.e., low, moderate, high). This classification was rather conservative since it was based on the presence or absence of traditional coronary risk factors such as age, physical inactivity, obesity, family history, dyslipidemia, hypertension, prediabetes, and smoking status. For adults who were categorized as moderate or high risk, it was recommended that most undergo a medical exam, exercise test, and/or obtain medical clearance prior to participating in moderate-to-vigorous intensity physical activity. The new ACSM guidelines no longer include cardiovascular risk factor profiling as part of the exercise preparticipation algorithm, which is a considerable change from past approaches to screening. Several important considerations provided the impetus for this change in approach (30).
Given the high prevalence of CVD risk factors in adults, the old approach proved to be too inclusive. For example, a relevant study (31) examined a nationally representative sample of 6785 adults aged ≥40 years in the 2001 to 2004 National Health and Nutrition Examination Survey (NHANES) database. The investigators calculated the proportion of adult participants who would receive a recommendation for physician consultation before starting an exercise program based on the American Heart Association/ACSM preparticipation questionnaire. Interestingly, the investigators reported that approximately 95% would be advised to consult a physician before exercising based on these conventional screening guidelines. This also proves to be particularly true for behavioral lifestyle programs based on the DPP aimed at reducing risk since these programs tend to target overweight individuals at risk for diabetes and/or metabolic syndrome. In applying the former guidelines, essentially all participants were required to obtain medical clearance and/or undergo peak or symptom-limited exercise testing before initiating a moderate-intensity exercise program such as brisk walking.
In addition to the high prevalence of CVD risk factors, the low frequency of fatal and non-fatal exercise-related cardiac events is another reason for the shift in approach (32–36). In the DPP, although there were some small differences in the incidence of musculoskeletal symptoms, there were no differences between the lifestyle group and the other groups in terms of adverse cardiovascular events related to hospitalizations or deaths (3). In considering screening for CVD and the safety of physical activity it is important to put the risk of activity interventions into perspective.
Clearly, for the general population, the benefits of physical activity not only outweigh the acute risks (37) but regular participation in moderate-to-vigorous physical activity is associated with a decrease in the risk of an exercise-related acute myocardial infarction (38–40). However, there is an increased relative risk of sudden cardiac death during vigorous-intensity exercise in habitually sedentary individuals with occult or known CVD, particularly when the activity bout is sudden and unaccustomed. Although the relative risk of cardiovascular events is higher for sudden vigorous physical activity, the absolute risk of these events is extremely low and most community physical activity programs like those based on the DPP do not encourage vigorous intensity activity.
A recent study (41) prospectively evaluated sudden cardiac arrest during sports in middle-aged adults over a 10-yr period. The investigators reported that the burden of sports-associated sudden cardiac arrest was relatively low when compared to the overall rate in the community. They also found that a substantial proportion of individuals who experienced sudden cardiac arrest reported having had symptoms in the days or weeks before the event, a finding also reported by others (42). However, this study was conducted in middle-aged adults participating in recreational sports, a cohort that does not necessarily reflect the population participating in lifestyle interventions where the primary form of activity is moderate-intensity walking.
Community-based lifestyle prevention programs, like those based on the DPP, tend to mitigate risk by recommending a “start low and go slow” approach with moderate intensity physical activity as the goal behavior. The incidence of acute cardiovascular events in individuals during light-to-moderate intensity exercise, such as those prescribed in these community-based interventions, appears to be extremely low (30, 42) making it a high benefit, lower risk activity.
The unknown effectiveness of pre-exercise medical evaluation is another reason for the shift in approach. Few data are available to substantiate routine screening recommendations or that physician clearance prior to participation in a physical activity program improves safety (31, 40). How to accurately identify asymptomatic individuals at risk for an exercise-related acute cardiovascular event, even if a preliminary medical examination is undertaken, remains unclear. The use of graded exercise testing to identify unknown CVD in asymptomatic individuals is controversial (40). It has become increasingly apparent that exercise testing is a poor predictor of future cardiovascular events as most acute coronary events evolve from vulnerable plaque rupture in previously non-obstructive coronary lesions (40, 43). Accordingly, it appears impractical to use exercise testing to prevent acute cardiovascular events in asymptomatic exercisers (34). Furthermore, unnecessary referrals for diagnostic testing can lead to high rates of false-positives in some populations, which can result in additional costly noninvasive and invasive testing.
Lastly, the requirement for medical clearance prior to initiating a physical activity program is another potential barrier for many who want to become more physically active. Many programs that require a preparticipation form to be completed by a medical provider place the burden of this administrative task on the participant. If the provider in turn requires a physical examination and/or exercise testing before completing the form, the individual may have to coordinate time off work, child care, and transportation to a medical visit at which he or she may be responsible for a co-payment and related costs. Because habitually sedentary individuals often perceive numerous barriers to the initiation and maintenance of a physical activity program (44), decreasing the need for medical clearance may help to eliminate another barrier. Furthermore, many community interventions attempt to reach traditionally underserved populations who may lack access to primary care providers or other medical services. Even for those in underserved communities who have access to care, the above-referenced logistical barriers may be more challenging, and individuals may experience additional impediments (e.g., language) when interacting with the healthcare system. In situations where obtaining clearance for physical activity may be unrealistic, the reach of programs, particularly in underserved communities in greatest need, is significantly compromised. Additionally, as practitioners work to extend the reach of physical activity interventions using innovative technology-based modes of delivery (45), the requirement for medical clearance by a physician may not be feasible.
The new ACSM guidelines (28) on exercise preparticipation screening are based on the participant’s current level of physical activity; known cardiovascular, metabolic or renal disease; presence of signs and/or symptoms suggestive of CVD; and, the anticipated exercise intensity ( Table 1 ). These characteristics have been identified as important modulators of exercise-related acute cardiovascular events (30).
Comparison of previous and updated ACSM guidelines on exercise preparticipation screening