Noting that “Being physically active is one of the most important steps that Americans of all ages can take to improve their health,” the US Department of Health and Human Services (HHS) published in 2008 “Physical Activity Guidelines for Americans” (PAGI).1 The primary goal of this document was to provide “science-based guidance to help Americans aged 6 years and older improve their health through appropriate physical activity.” Famously, this document introduced Americans to the need to achieve 150 minutes of moderately intense aerobic activity per week to achieve health benefits, a goal quickly modified to read 30 minutes of aerobic activity per day, 5 days per week. This document also pointed out the following:
- Exceeding the aforementioned guideline provided additional health benefits;
- Some activity was better than none;
- Individual exercise sessions should last at least 10 minutes;
- Virtually all members of our society could derive benefit from exercising;
- Resistance training is an essential, not an adjunctive physical activity; and
- Benefits derived from engaging in physical activity far outweighed the possibility of adverse effects.
Relative to cancer, these guidelines suggested that there was strong evidence to link greater levels of physical activity with a lower risk of developing colon and breast cancer and a moderate risk of developing lung and endometrial cancer. Interestingly, this report speculated that these benefits, in contrast to the effects of physical activity on cardiovascular disease, may have required years of participation in regular physical activity to be expressed. Evidence available in 2008 suggested that these benefits occurred only if physical activity exceeded the recommended 150 min/wk. Cancer survivors who exercised were reported to have a better quality of life and improved “physical fitness” than sedentary survivors. These benefits were not linked to specific amounts of physical activity and the notion of physical fitness probably referred to physical function. Cancer survivors and other populations of chronic disease were told to carefully match their participation in physical activity with their physical abilities in order to ensure their safety. This document placed the burden of developing exercise programs on health care providers by advising cancer survivors (and others with chronic diseases) to “consult their health care providers about the types and amounts of activity appropriate for them.”
Guidance was also provided about engaging in physical activity for those older than 65 years, a subgroup that includes the majority of cancer survivors. These individuals, like younger and healthier adults, should avoid inactivity, meet the 150 min/wk goal for aerobic activity, can expect additional health benefits by engaging in physical activity beyond this amount, and should engage in moderate- to high-intensity resistance. Recommendations for this specific age group included:
- Be as physically active as their abilities and conditions allow;
- Engage in balance training exercises; and
- Match their level of effort in doing physical activity to their level of fitness.
Older adults were also called upon to “understand whether and how their conditions (frequently functional limitations) affect their ability to do regular physical activity safely.” Return to engaging in physical activity following an illness or injury should start at a lower level and progress slowly. These guidelines specifically call for the use of a 0 to 10 rating of perceived exertion scale to define exercise intensity with a 5 to 6 defining moderate activity.
Now let's fast forward to late 2018 when HHS issued a 2nd edition of Physical Activity Guidelines for Americans (PAGII).2 This revised edition was written in response to an already high and still expanding incidence of chronic, preventable diseases in Americans and their diminishing participation in physical activity and exercise, a combination that has resulted in serious economic and health consequences. PAGII has retained the fundamental exercise guideline that calls for accumulating a minimum of 150 minutes of moderately intense aerobic physical activity per week and engaging in resistance training 2 days per week. However, PAGII softens this guideline somewhat. First, and perhaps most importantly, it calls for individuals to simply move more during their daily lives since evidence suggests that even limited physical activity provides benefit and reduces disease risk. This recommendation eliminates the previous minimum exercise duration of 10 minutes and provides assurance that even the performance of daily activities can provide health benefits. These guidelines point out that acute exercise bouts by themselves provide health benefits. For example, a single exercise bout increases insulin sensitivity, improves blood lipid profiles for upwards of 24 hours, and reduces blood pressure in hypertensive males. In softening the previous guidelines, PAGII seeks to extend the perception that the benefits of exercise accrue not only during “gym time” but also during physical movement carried out in the context of daily living. The PAGII encourages everyone to extend their view of exercise beyond the confines of the gym and track and to think about the benefits to be gained by exercise/physical movement carried out in the context of daily living. This approach does not minimize the well-established goal of accumulating 150 minutes of aerobic activity per week; rather, it gives individuals who are simply unable to achieve this goal because of physical limitations the sense that they can derive health benefits by being as active as they possibly can be.
Relative to oncology, PAGII identifies 8 cancers whose risk is reduced by participation in regular physical activity:
- Breast (included in PAGI)
- Colon (proximal and distal) (included in PAGI)
- Esophageal (adenocarcinoma)
- Lung (included in PAGI)
- Stomach (cardia and noncardia adenocarcinoma)
The PAGII add improvements in brain health in terms of improved cognition, reduced anxiety and depression risk, and improved sleep patterns to the list of benefits derived from participation in exercise training identified in PAGI. These changes are important, as these characteristics are adversely affected by cancer and/or its treatment. Fall risk, which is greater in cancer survivors, especially older cancer survivors and cancer survivors with advanced diseases, can be ameliorated by physical activity. PAGII specifically identifies “multicomponent physical activity” as a specific type of physical activity in the same vein as aerobic activities, and resistance/strength training, adding credibility to activities such as dancing, yoga, tai chi, and gardening, physical activities that are increasingly viewed as important therapeutic interventions for managing cancer survivors. Furthermore, this new designation of multicomponent physical activity creates an inclusive term that incorporates all types of physical activities that are viewed as essential in the comprehensive management of the cancer survivor.
I would like to conclude by pointing out that PAGII assigns broader responsibilities to clinicians than were included in PAGI. The former calls for the consideration of physical activity as a primary or adjunctive therapy for many common clinical conditions (including cancer) and calls for clinicians to assume a major role in advancing its key concept, namely, encouraging people to move. Clinical examinations should routinely include the assessment of physical activity. Physical inactivity is an important data point for health care providers and helping to identify sedentary patients, a patient population that can benefit from increased participation in physical activity. We have known for decades that optimal physical fitness is a significant contributor to improved personal and public health. PAGII provides further evidence supporting this contention and identifies how health care providers can advance this cause. To download and get updates on these guidelines, go to the National Physical Activity Plan Alliance: http://physicalactivityplan.org/index.html. The guidelines contained in PAGII are written broadly, so your challenge in 2019 and beyond is to translate these guidelines to the individual patients in your practice.
G. Stephen Morris, PT, PhD, FACSM
1. US Department of Health and Human Services. Physical Activities Guidelines Advisory Committee. Physical Activity Guidelines Advisory Committee Report. Washington, DC: US Department of Health and Human Services; 2008.
2. US Department of Health and Human Services. Physical Activity Guidelines for Americans. 2nd ed. Washington, DC: US Department of Health and Human Services; 2018.