New Physical Activity Guidelines Based on Decade of Research

In 2008, the United States Department of Health and Human Services (HHS) published the first edition of their “Physical Activity Guidelines for Americans” after assessing mountains of science-based evidence available at the time. A decade later, HHS has just released updated guidelines for daily/weekly prescriptive doses of exercise based on the past 10 years of evidence-based research.

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The new guidelines offer detailed recommendations for how much we need to move our bodies at various stages of life to promote physical and psychological well-being and prevent disease across the human lifespan. The most recent physical activity guidelines were presented November 12 at the American Heart Association Scientific Sessions 2018 in Chicago, Illinois. These findings were also published today in JAMA.

The latest recommendations from HHS are based on the 2018 Physical Activity Guidelines Advisory Committee Scientific Report which lays out specific types of aerobic and muscle-strengthening exercise along with how much and what types of physical activity are optimal for promoting better health outcomes in a wide range of demographic groups.

Regular physical activity is one of the most critical lifestyle choices individuals of all ages can make to improve overall health, reduce morbidity, and increase longevity. According to this new report, approximately 80 percent of U.S. adolescents and adults are insufficiently active. In the United States, it’s estimated that a lack of regular exercise and failure to meet existing physical activity guidelines is associated with $117 billion in annual healthcare costs.

On the bright side, the latest science-based evidence reaffirms that regular physical activity can help people feel better, think better, sleep better, function better, and live longer.

The new guidelines lay out four categories of physical activity: (1) Aerobic exercise, (2) Muscle-strengthening activity, (3) Bone-strengthening activity, (4) Balance-improving activity.

1. Aerobic Exercise

During aerobic activity (also referred to as cardiorespiratory exercise, “cardio,” or endurance training) large muscle groups are moved continuously and rhythmically for a sustained period of time. Aerobic activity increases heart rate, causes breathing to become more labored, and usually results in breaking a sweat.

Three Components to Aerobic Exercise: Intensity, Duration, and Frequency

1. Intensity describes the degree of effort someone exerts during aerobic activity. Intensity ranges from “light” (housework or a slow walk), to “moderate” (equivalent to a brisk walk or easy bike ride), and “vigorous” (equivalent to jogging or climbing many stairs).
2. Duration describes how many minutes someone engages in aerobic activity during each session.
3. Frequency describes how many times a week someone engages in any type of aerobic activity.

2. Muscle-Strengthening Activity

Muscle-strengthening activities include lifting free weights, strength-training machines, or any type of resistance training that builds muscle. Muscle-strengthening activities can also include the use of your body weight for resistance and elastic bands with varying degrees of tension.

3. Bone-Strengthening Activity

Bone-strengthening activities exert weight-bearing force on different bones in the body and promote the strengthening and maintenance of healthy bone mass. Bone-strengthening activities include some types of aerobic activity (such as jogging) and muscle-strengthening exercises.

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4. Balance-Improving Activity

Balance-improving exercises strengthen various muscles in the body that help people stay steady on their feet and maintain the brain’s balance centers in ways that can reduce the risk of falling.

Four Key Physical Activity Guidelines for Adults from HHS (2018)

1. Adults should move more and sit less throughout the day. Some physical activity is better than none. Adults who sit less and do any amount of moderate-to-vigorous physical activity (MVPA) gain some health benefits.
2. For substantial health benefits, adults should do at least 150 minutes (2 hours and 30 minutes) to 300 minutes (5 hours) a week of moderate-intensity, or 75 minutes (1 hour and 15 minutes) to 150 minutes (2 hours and 30 minutes) a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic activity. Preferably, aerobic activity should be spread out across a few days during the week.
3. Additional health benefits are gained by doing physical activity beyond the equivalent of 300 minutes (5 hours) of moderate-intensity physical activity a week.
4. Adults should also do muscle-strengthening activities of moderate or greater intensity that involve all major muscle groups on 2 or more days a week, as these activities provide additional health benefits.

Absolute Intensity vs. Relative Intensity

• Absolute intensity refers to the rate of work being performed and does not consider the physiologic capacity of the individual. This is often expressed in metabolic equivalent of task (MET) units. Moderate-intensity physical activities such as walking briskly or raking the yard have a MET level of 3 to 5.9 METs.
• Relative intensity takes into account or adjusts for a person’s cardiorespiratory fitness. Someone who is more fit will perceive an exercise to be easier and thus rate it as of lower relative intensity than someone who is less fit.

In addition to these guidelines for adults, the new HHS report offers guidelines for other age groups and populations:

• Preschool-aged children (3 through 5 years) should be physically active throughout the day to enhance growth and development.
• Children and adolescents (aged 6 through 17 years) should do 60 minutes or more of moderate-to-vigorous physical activity (MVPA) daily.
• Older adults (65+ years of age) should do multi-component physical activity that includes balance training as well as aerobic and muscle-strengthening activities.
• Pregnant and postpartum women should do at least 150 minutes of moderate-intensity aerobic activity a week.
• Adults with chronic conditions or disabilities, who are able, should follow the key guidelines for adults and do both aerobic and muscle-strengthening activities.

The authors conclude, "The Physical Activity Guidelines for Americans, 2nd edition, provides information and guidance on the types and amounts of physical activity that provide substantial health benefits. Health professionals and policymakers should facilitate awareness of the guidelines and promote the health benefits of physical activity and support efforts to implement programs, practices, and policies to facilitate increased physical activity and to improve the health of the U.S. population.”