Tutorial:
How Much Exercise Do I Need?
JoAnn E. Manson, MD, DrPH
Division of Preventive Medicine
Brigham and Women's Hospital
Professor of Medicine
Harvard Medical School
Exercise Guidelines
• Previous exercise recommendation
(AHA 1981, ACSM 1985):
• intense or vigorous exercise
• at least 20 minutes continuously
• at least 3 times per week
Exercise Guidelines
• Exercise recommendation
(CDC and ACSM 1995; U.S. Surgeon
General 1996)
“Every adult should accumulate 30
minutes or more of moderate-intensity
physical activity on most, preferably
all, days of the week.”
• Recent IOM guidelines on diet, September 02,
call for at least 1 hr/day of moderate physical
activity.
• These guidelines are meant to keep weight in
healthy range.
• 30 min/day still sufficient for cardiac health,
but insufficient to maintain healthy weight.
World Health Organization, 2004
• At least 30 minutes of regular, moderate-intensity
physical activity on most days reduces the risk of
cardiovascular disease, diabetes, colon cancer, and
breast cancer.
• Muscle strengthening and balance training can
reduce falls and increase functional status among
older adults.
• More activity may be required for weight control.
Percent
Percent of U.S. Adults Engaging in Regular Leisure-time
Physical Activity,* by Gender and Age, 1997-98
50
45
40
35
30
25
20
15
10
5
0
Men
Women
18-24
25-44
45-64
65-74
Age (years)
75+
* Regular activity=light-to-moderate activity 5 times per week for 30 min each time, or
vigorous activity 3 times or more per week for 20 min each time.
Source: NCHS, 2002.
Number of Minutes of Activity to Burn 150 Calories
Climbing stairs
Shoveling snow
Running 2 miles
Jumping rope
Cycling 4 miles
Swimming laps
Doing water aerobics
Walking 2 miles
Raking leaves
Pushing a stroller (1 1/2 miles)
Dancing fast
Gardening
Playing volleyball
Washing windows or floors
Washing or waxing a car
0
5
10
15
20
25
30
Minutes
35
40
45
50
55
60
Physical Activity
• Biological mechanisms:
• improvements in lipid profile
• blood pressure lowering
• improvement in glucose tolerance
• reduction in adiposity
• enhanced fibrinolytic activity
• stress reduction
Physical Activity
• Reduces risk of:
• coronary heart disease
• stroke
• diabetes mellitus (type 2)
• osteoporosis
• certain types of cancer
(colorectal, breast, prostate)
Women's Health Initiative
(J Manson, et al. NEJM 2002)
1.2
P, trend < 0.001
MV RR of CVD
1.0
0.8
0.6
0.4
0.2
0.0
0.2.4
2.5-7.2
7.3-13.4
13.5-23.3
Physical Activity, MET-Hr/Wk
23.4+
Walking vs Vigorous Exercise and Risk of CVD:
Women's Health Initiative
(J Manson, et al. NEJM 2002)
MV RR of CVD
1.2
P, trend < 0.001
1.2
1.0
1.0
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0.0
P, trend = 0.01
0.0
0
0.1-2.5
2.6-5.0
5.1-10.0
Walking, MET-Hr/Wk
>10.0
0
1-60
61-100
101-150
Vigorous
Exercise, Min/Wk
>150
Walking and the Risk of Heart Disease:
Nurses' Health Study
(J Manson, et al. NEJM 1999)
Relative Risk of
Coronary Heart Disease
1.0
1.0
0.8
0.7
0.7
0.6
<10
minutes
10-59
minutes
0.6
1-2.9
_
>3
Casual
Normal
hours
hours
(<2 mph)
(2-2.9 mph)
Time per Week Spent Walking Briskly (3 mph)
Usual Walking Pace
Brisk
(3
mph)
Relative Risk of Coronary Heart Disease (CHD)
Vigorous Activity vs Walking: Women’s Health Study
(I Lee, et al. JAMA 2001)
1.2
1.2
1.00
0.75
0.8
1.00
P for trend<0.001
0.60
0.6
0.41
0.4
P for trend<0.001
1
Relative Risk of CHD
Relative Risk of CHD
1
0.86
0.8
0.6
0.49
0.48
1 to 1.5 hr
2+ hr
0.4
0.2
0.2
0
0
0
1-199
200-499
Energy expended on vigorous
recreational activities (kcal/week)
500+
0
1 to 59 min
Time spent walking per week
Relative risks of coronary heart disease according to daily walking distance
among elderly men in the Honolulu Heart Program
Relative risk of
coronary heart disease
3
2.5
P for trend=0.002
2.30
2.10
2
1.5
1.00
1
0.5
0
<0.25
0.25 to 1.5
Distance walked, miles/day
Source: Hakim AA et al. Circulation 1999;100:9-13.
1.5+
Relative risk of coronary heart disease according to quintile of walking
energy expenditure (left panel) and usual walking pace (right panel)
among men in the Health Professionals’ Follow-up Study
1.2
1.2
P for trend=0.04
1.00
1.00
1.00
1.0
0.90
0.82
0.8
0.6
0.4
R elative R isk of C H D
R elative R isk o f C H D
1.0
P for trend<0.001
1.02
0.8
0.74
0.60
0.6
0.50
0.4
0.2
0.2
0.0
0.0
1
2
3
4
5
Quintile of walking energy expenditure
(MET-hr/wk)*
*Quintiles: 0-1.19, 1.20-3.49, 3.50-6.99, 7.00-14.74, 14.75+ MET-hr/wk
Source: Tanasescu M, et al. JAMA 2002;288:1994-2000.
<2
2 to 3
3 to 4
Usual walking pace, mph
4+
Walking and the Risk of Stroke
1.0
Relative Risk
of Stroke
0.8
0.7
<10
minutes
10-59
minutes
1-2.9
hours
Time per Week Spent Walking Briskly (3
mph)
Source: Hu FB, et al. Nurses’ Health Study; JAMA 2000
0.7
_
>3
hours
Walking and the Risk of Type 2 (Adult-Onset) Diabetes
p for trend <0.001
1.0
1.0
Relative Risk
of Diabetes
0.8
0.8
0.7
<10
minutes
10-30
minutes
31-59
1-2.9
minutes
hours
_
>3
hours
Time per Week Spent Walking Briskly (3 mph)
Source: Hu FB, et al. Nurses’ Health Study; JAMA 1999
Exercise and a Woman’s Risk of Breast Cancer
1.0
Relative Risk
0.93
0.63
Lowest
Moderate
Level of Physical Activity
Source: Adapted from Thune I, et al. N Engl J Med 1997
Highest
Physical Activity and the Risk of Colon Cancer
Relative Risk of
Colon Cancer
1.0
1.0
0.7
0.6
<1
_
>1
Hours per Day
of Moderate
Activity
Source: Nurses’ Health Study/Harvard’s Brigham and Women’s Hospital
_
<1/2
_
>1/2
Hours per Day
of Vigorous
Activity
Exercise and a Woman’s Risk of Hip Fracture
Relative Risk
1.0
0.73
0.58
Lowest
Moderate
Level of Physical Activity
Source: Adapted from a study of the Osteoporotic Fractures Research Group; Ann Intern Med 1998
Highest
Physical Activity and the Risk of Premature Mortality
1.0
Relative Risk
of Mortality
0.8
0.7
<1
1-3.9
_
>4
Hours per Week of Moderate or Vigorous Activity
Source: Rockhill B, et al. Nurses’ Health Study; Am J Pub Health 2001
Short versus Long Bouts of Exercise: Randomized Trials
• Meta-analysis: “Small randomized controlled trials
showed that improvements in measures of
cardiorespiratory fitness did not differ significantly
between training regimens based on long or short
sessions.” Hardman AE. Med Sci Sports Exerc 2001;33:S421-7.
• “ … Three short bouts (10 min) of brisk walking
accumulated throughout the day are at least as effective
as one continuous bout of equal total duration in reducing
cardiovascular risk and improving aspects of mood in
previously sedentary individuals.” Murphy M et al. Med Sci
Sports Exerc 2002;34:1468-74.
Relative Risks of Coronary Heart Disease According to
Time Spent Weight Training Among Men in the Health
Professionals’ Follow-up Study
Relative risk of
coronary heart disease
1.2
1.0
P for trend=0.001
1.00
0.88
0.8
0.69
0.6
0.4
0.2
0.0
0
<0.5
Weight training, hours/week
Source: Tanasescu M, et al. JAMA 2002;288:1994-2000.
0.5+
Percentage Change in Risk of Developing Obesity According to
TV Watching and Other Sedentary Behaviors
Source: Hu F, et al. JAMA 2003
Relative Risk of Developing Obesity According to Time Spent
Watching TV and Physical Activity Level
Source: Hu F, et al. JAMA 2003
Strategies to Ï Activity
• Get a pedometer
Aim for 10,000 steps/d
(2,500 steps = ~1 mile)
5,000 steps in "structured" activity
5,000 steps in "lifestyle" activity
• Strength training
15-20 minutes 2-3 x/week
Strategies
•
•
•
•
•
Make activity a priority in your life
Develop the self-identity of an exerciser
Set clear and realistic goals
Write down your goals (calendar can be helpful)
Try to exercise at the same time each day to make it
a habit
• Expect setbacks and don't let them derail you
• Reward yourself
‘ Staying healthy is the most important thing you can do
for the people you love. ‘
Source: Manson J, Amend P. The 30-Minute Fitness Solution; 2001.
Top Ten Tips for Adding Walking to a Busy Schedule
•
•
•
•
•
•
•
Park your car at the farthest end of the parking lot and walk.
•
Combine walking time with family time; push your children in a stroller or
have them bicycle along as you walk.
•
Trade child care with a neighbor so you can both have an opportunity to go
outside and walk.
•
Join (or start) a community or neighborhood walking club.
Get off the subway or bus a stop early and walk a few blocks to work.
Take a walk during your lunch break, alone or with a walking partner.
Take the stairs rather than the elevator.
Take your dog for a walk.
At the mall, walk briskly around the perimeters while you window-shop.
Instead of having a cup of coffee with a friend or colleague, get together for
a walk and talk.
Source: Manson J, Amend P. The 30-Minute Fitness Solution; 2001.
Community-Based Strategies for Promoting Physical Activity
Schools:
• Advocate for required daily physical education for all students.
• Petition to allow school gymnasiums to be open on evenings and weekends for
community recreation.
•
Car-pool to provide students' transportation to and from sports practice and
playing fields.
Workplace:
•
Advocate for employers and health care organizations to create benefit packages
that include wellness programs and reimbursement for fees associated with
health clubs and other recreational activities.
Neighborhoods:
•
•
Advocate for community sidewalks, walking trails, bicycling paths, safe parks
with good lighting and police patrols.
Start (or join) a neighborhood or community walking program.
Source: Manson J, Amend P. The 30-Minute Fitness Solution; 2001.