transition to a new era of genome-informed medical
care will need a team approach, he added, incorporating medical and genetics professionals, ethicists,
and health care delivery organizations. ■
REFERENCES:
1. Ashley EA, Butte AJ, Wheeler MT, et al. Lancet.
2010;375:1525-35.
2. Committee on a Framework for Development of a New
Taxonomy of Disease, National Research Council. Washington, DC; National Academies Press; 2011.
3. Ashley EA. JAMA. 2015;313:2119-20.
4. Wheeler MT, Ashley EA. J Am Coll Cardiol. 2015;65:570-2.
5. Coppini R, Ho CY, Ashley E, et al. J Am Coll Cardiol.
2014;64:2589-2600.
Physical Activity as Vital Sign
The exercise prescription to prevent CAD
W
e have physical activity recommendations from the Centers for Disease
Control and Prevention,1 the American College of Sports Medicine,2 the U.S. Surgeon
General,3 the American Heart Association,4 and the
ACC.5 All of the publications affirm the primary
role of exercise in preventing chronic disease and in
maintaining health throughout life. Several principles
emerge from these documents, including:
• any exercise is better than none,
• more exercise is better than less,
• different types of exercise (aerobic versus resistance) yield distinct favorable outcomes,
• and activity recommendations should be enabling
and flexible, and avoid setting up barriers.
In terms of the mode of exercise, there is aerobic,
resistance, flexibility, and balance exercises as well as
specific types of activities, such as walking and biking.
Frequency is determined by the number of active sessions per day or per week and often qualified as being
the number of sessions (bouts) of exercise/activity ≥
10 min in duration/length
Intensity is determined by the rate of energy
expenditure (TABLE). Walking at 3.0 miles per hour
requires 3.3 metabolic equivalents (METs) of energy
expenditure and is therefore considered a moderateintensity activity that noticeably accelerates heart
rate (HR). Vigorous-intensity activities are those that
require a large amount of effort and causes rapid
breathing and a substantial increase in HR. Adherence may be better with moderate activities, especially
among sedentary individuals.
You may know what METs stands for without
specifically understanding what it means. One MET
is defined as the energy cost of sitting quietly and is
equivalent to a caloric consumption of 1 kcal/kg/hr. In-
stead of sitting quietly, a person’s caloric consumption
is three to six times higher when being moderately
active (3-6 METs) and more than six times higher
when being vigorously active (> 6 METs). (Some
recommendations include 6 METs in the “moderate”
category while others consider it the starting point of
vigorous activity.)
How does physical activity prevent CHD? Vera
Bittner, MD, is a professor of medicine and Section
Head of Preventive Cardiology at the University of
Alabama, Birmingham; she was a co-author of the
AHA scientific statement.4 To answer the question, Dr.
Bittner points to the Women’s Health Study, which included self-reported physical activity.6 Based on increasing levels of activity levels, there was a strong dose-dependent reduction in CHD (up to 52%) and CVD (up to
41%). Changes in risk factors (e.g., hypertension, lipids,
BMI, even blood glucose levels) explained 35.5% of the
CHD reduction seen across almost 11 years of followup as well as 59.0% of the CVD reduction seen.
On average, according to the recent ACC/AHA
lifestyle guidelines,5 aerobic activity compared with
control interventions, is associated with:
• reduction in low-density lipoprotein cholesterol
(LDL) of 3 to 6 mg/dL,
• reduction in non-high-density lipoprotein cholesterol (HDL) of 6 mg/dL,
• no consistent effect on triglycerides or HDL, and
• a reduction in both systolic (-2 to -5 mm Hg) and
diastolic (-1 to -4 mm Hg) BP.
Again, compared with control interventions, adults
undertaking regular resistance training experience
reductions (on average) in LDL, triglycerides, and nonHDL cholesterol of 6 to 9 mg/dL.
AN EXERCISE PRESCRIPTION
What is Moderate-intensity Versus Vigorousintensity Physical Activity?
TABLE
Moderate Physical Activity
(3 - 5.9 METS)
Vigorous Physical Activity
(≥6 METS)
Brisk walking (≥ 3 mph)
Dancing (think ballroom rather than rave)
Bicycling (< 10 mph)
Tennis (doubles)
Water aerobics
General gardening
Housework and domestic chores
Race-walking, jogging, or running
Swimming laps
Tennis (singles)
Aerobic dancing (definitely disco and not ballroom)
Bicycling (≥ 10 mph)
Jumping rope
Heavy gardening (more digging than weeding)
MET = metabolic equivalent.
ACC.org/CSWN
What are the attributes of an
“ideal” exercise prescription
to prevent CAD? Dr. Bittner
suggests a universal yet individualized approach, based on
physiologic age, “athletic” ability/
fitness, comorbidities, and (of
course) patient preferences.
Also for consideration: feasibility, whether that relates to time,
equipment, or environment.
(Don’t recommend a health club
membership to someone who
lives an hour away from the
nearest such facility.)
In brief, any activity is better
To listen to the
than no activity and more activity
interview with Vera
Bittner, MD, visit
provides incremental benefits.
the CSWN YouTube
Also, when considering an exerchannel or scan the
cise prescription, consider one
QR below. Interview
conducted by Deepak
that is sustainable and safe. Yes,
L. Bhatt, MD.
MI risk is increased during vigorous activity, especially among
those not habitually active. However, Dr. Bittner emphasizes that
for inactive people who gradually
progress to moderate-intensity activity, there is no known increased
risk of sudden cardiac events.
There is also a very low risk of musculoskeletal injuries.
According to the 2008 physical activity guidelines,1 habitually active persons can gradually increase
to vigorous intensity without consulting a health care
provider. Conversely, people who develop new symptoms when increasing their levels of activity should
consult a health care provider. Plus, people with symptoms or known chronic con