The U.S. Department of Health and Human Services issues
the Physical Activity Guidelines for Americans, which provides
science-based guidance to help Americans aged 6 and older
improve their health through appropriate physical activity. The
most recent version of the guidelines was published in 2008.
Key Guidelines for Children and Adolescents
• Children and adolescents should do 60 minutes or more of
physical activity daily.
• Most of this time should be either moderate-to-vigorous-intensity aerobic physical activity like running, and should
include vigorous-intensity physical activity at least three days
• Muscle- and bone-strengthening exercises like pushups or
jumping rope, respectively, should be a part of daily physical
activity and occur at least three days of the week.
Key Guidelines for Adults
• All adults should avoid inactivity. Some physical activity is
better than none, and adults who participate in any amount of
physical activity gain some health benefits.
• Adults should undertake at least 150 minutes a week of
moderate-intensity activity like a brisk walk, or 75 minutes
a week of vigorous-intensity aerobic physical activity like
running, or an equivalent combination of the two. Aerobic
activity should be performed for at least 10 minutes at a time,
and be spread throughout the week.
• Ideally, adults should increase their aerobic physical activity
to 300 minutes a week of moderate intensity, or 150 minutes
a week of vigorous-intensity, aerobic physical activity, or an
equivalent combination of the two.
• Adults should also undertake muscle-strengthening activities
that are moderate or high intensity and involve the legs, hips,
back, abdomen, chest, shoulders, and arms on two or more
days a week.
For older adults, those who are pregnant, and or those with
disabilities, these guidelines are modified; see http://www.
health.gov/paguidelines/guidelines/summary.aspx for further
For cancer survivors, it is recommended that they follow the
2008 Physical Activity Guidelines for Americans with specific
exercise programming adaptations based on disease and
treatment-related adverse effects ( 65, 66).
colon compared with individuals who did not spend any time in
sedentary work ( 67). In a second study, patients with colorectal
cancer who spent six or more hours a day sitting after their
diagnosis had a dramatically increased risk of death from their
cancer compared with patients who spent fewer than three
hours a day sitting ( 68). Likewise, a large-scale study also
showed that the more time a person spent sitting, the greater
their risk of death from any cause, regardless of their level of
physical activity ( 69).
Conversely, research has shown that for patients with certain
forms of cancer, including breast, colorectal, and prostate
cancers, physical activity improves outcomes by reducing
recurrence and increasing survival ( 8, 70-73).
Clear guidelines for physical activity for cancer survivors have
been published ( 8, 65, 66). However, it appears that these
have mostly been applied in clinical settings and research
interventions, and that they have not yet become general
standards of practice in the United States.
There are many barriers to increasing physical activity among
cancer survivors and the general public. More research and
resources at all levels are needed if this lifestyle modification is
to be widely adopted.
Looking For Cancer: Who,
When, and Where
We know that most cancers arise from genetic mutations
that have accumulated during the patient’s lifetime (see
Developing Cancer; p. 17). Our knowledge of the causes,
timing, sequence, and frequency of these pivotal changes is
increasing, as is our insight into the specific implications of the
changes. This knowledge provides us with unique opportunities
for developing the means to prevent cancer onset or to detect it
and intervene earlier in its progression.
Unfortunately, we have also learned that it is not always
easy to identify at-risk patients or those with early-stage
disease. However, researchers and clinicians are looking to
pair our molecular understanding of cancer development with
indicators of cancer risk to create personalized prevention and
early-stage intervention programs. For example, some patients
may be able to reduce their risk by simply modifying their
behaviors. Others might need to increase their participation in
screening or early detection programs or even consider taking
a preventive medicine or having precautionary surgery (see
Tables 6 and 7, pp. 28 and 30, respectively).