Do We Really Need an Houre of Exercise Every Day?
Steve Daisey MPT, CSCS
"To maintain cardiovascular health at
a maximal level, regardless of weight,
adults and children should spend a total of
at least one hour each day in moderately
intense physical activity."
That recent statement which made headlines a few
weeks ago came from The National Academy of Sciences
(NAS). The "one hour of physical activity" request by
NAS is double what the surgeon general's report
recommended in 1996. As sometimes happens, the press
coverage that followed only served to dilute and
confuse the message.
Let's clarify this statement.
"Physical activity" is not the same as "exercise".
Physical activity is something, anything, that
substantially increases your energy expenditure -
leading to an "active lifestyle". Exercise, on the other
hand, is a higher-level activity that is intense enough
to increase overall physical fitness. An "active
lifestyle" has been shown in numerous studies to reduce
risk factors for coronary artery disease, stroke and
adult-onset diabetes (1-3).
The article (actually, more like an epic miniseries
at 936 pages) essentially states that to harness the
many benefits of exercise (prevention of stroke, heart
disease, etc.) and maintain body weight, one must engage
in an "active lifestyle." Through research and plenty of
mathematical formulas, the article defines an "active
lifestyle" as one which includes about 30 minutes of
exercise each day, and 30 minutes of "moderately intense
physical activities". What are examples of moderately
intense physical activities?
Examples would be a combination of activities such as
gardening, walking the dog, stair-climbing, golf,
tennis, taking out the trash, mopping, mowing the lawn
and vacuuming.
So to answer the question: No, we do not need to set
aside an hour of exercise every day to achieve the
benefits of an active lifestyle.
Do YOU Get Enough Physical Activity
Throughout the Day to be Considered "Active"?
NAS has actually developed a scale and some mildly
complex formulas to determine whether someone is
maintaining and deriving the benefits of an "active
lifestyle". The formulas result in a "physical activity
level ratio" or PAL ratio. I have turned these formulas
into a convenient online calculator to determine if the
accumulation of activity during YOUR day results in an
"active lifestyle".
First, enter the following:
Next, enter the number of minutes you spent performing
each of the below activities YESTERDAY (leave blank if
you did not engage in that activity). Be sure to enter
minutes for EVERY activity you were involved in
yesterday.
(The National Academy of Sciences recommends you
calculate your PAL ratio each day for a week, record the
numbers and take an average at the end of the week).
When you are finished, click "CALCULATE" below.
ACTIVITES - Mild Leisure Activities
Moderate Leisure Activities
Vigorous Activities
Activities of Daily Living
Your Physical Activity Level (PAL) Ratio is:
|
If your PAL Ratio is: |
Your Activity Level is Rated: |
| 1.90 and greater |
Very Active Lifestyle |
| 1.60 to 1.89 |
Active Lifestyle |
| 1.40 to 1.59 |
Low Active Lifestyle |
| 1.00 to 1.39 |
Sedentary Lifestyle |
Based on this formula an average male (30 years old, 160
pounds, 5'9" tall) can lead an "active lifestyle" by
jogging 30 minutes per day in addition to:
-
Going up and down stairs (4 minutes per day)
-
Walking (4 mph for a total of 20 minutes throughout the
day)
-
Sitting with light activity (4 hours per day)
-
Driving in the car (20 minutes per day)
-
Doing a few household chores (10 minutes per day)
-
Walking the Dog (15 minutes per day)
All of these are typical, moderate activities which many
of us perform throughout the day. By the end of a day,
this accumulates into the amount of activity needed for
an active lifestyle.
As stated before, The National Academy of Sciences
recommends you calculate your PAL ratio each day for a
week, record the numbers and take an average at the end
of the week. Obviously, you wouldn't mow the lawn or
take out the trash every day, and likely wouldn't
exercise every day as well.
Also, keep in mind this important bit of information
when deciding how to get enough activity: research shows
that three 10-minute bouts of exercise (walking/jogging)
per day may be just as effective as 30 minutes of the
same exercise (4). Many people do not get enough
exercise because they feel they need to set aside too
much time. You can still derive the benefits of exercise
by simply breaking it up throughout the day.
References:
1. Manson JE, et al: A prospective study of walking as
compared with vigorous exercise in the prevention of
coronary heart disease in women. N Engl J Med 1999 Aug
26;341(9):650-8.
2. Hu FB, et al: Physical activity and risk of stroke in
women. JAMA 2000 Jun 14;283(22):2961-7.
3. Hu FB, et al: Walking compared with vigorous physical
activity and risk of
type 2 diabetes in women: a prospective study. JAMA 1999
Oct 20; 282(15): 1433-9.
4. Murphy M, et al: Accumulating brisk walking for
fitness, cardiovascular risk, and psychological health.
Medicine & Science in Sports & Exercise 2002;
34(9):1468-1474
Formulas for calculating PAL Ratio:
Change in PAL for each activity = (# of METs - 1) * (BEE
/ (1440 * 0.0175) * weight in kg) * (minutes spent
during activity / 1440 minutes)
PAL Total = 1.1 + (Change in PAL1+...Change in PALn)
Men
BEE (Basal Energy Equivalent) = 293 - (3.8 *age) +
(456.4 * height in meters) + (10.12 * weight in kg)
Women
BEE (Basal Energy Equivalent) = 247 - (2.67 * age) +
(401.5 * height) + (8.6 * weight in kg)
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