The 2008 Physical Activity Guidelines for Americans140 use the term “physical activity”
to refer to bodily movement that enhances health. This is a different lens
than considering physical activity that aims for athletic fitness. Baseline activity
refers to the light-intensity activities of daily life, such as standing, walking slowly,
and lifting lightweight objects. People who do only baseline activity are considered
to be inactive.

The 2008 Guidelines asserted that very short (less than 10 minutes) episodes of
moderate- or vigorous-intensity activity, such as climbing a few flights of stairs
were not long enough to count toward meeting the recommended Guidelines for
Physical Activity. New research, described in the 2018 Physical Activity Guidelines
Advisory Committee Scientific Report, on high-intensity training of very short
duration, and studies that used activity trackers that measured total minutes per day
of moderate or vigorous physical activity, show that a health effect occurs with just
about any duration of an activity. In general, shorter, more frequent physical
activities are equivalent to less frequent activities of longer duration if the total time
is the same. The health benefits of a workout of 30 minutes on five days a week are
the equivalent of 50 minutes on three days a week.

One 6-year study based on accelerometer readouts found that replacing just 30 minutes
of sedentary time with an equal amount of light activity was associated with
a 14% reduced risk of mortality. The study found that replacement of sedentary
time with moderate to vigorous activity was related to 50% mortality risk reduction,
and there was a 42% reduced risk of mortality when light physical activity was replaced
by moderate to vigorous activity.

There is evidence from a 15-year observational study in the U.K. that one or two
(probably weekend) workouts are just as beneficial to avoid premature death as is
the same total amount of physical activity three or more times during a week.
Many of the study subjects were men, about half of whom engaged in vigorous
exercise just once a week. The study found that men and women who exercised in
bouts of less than 10 minutes duration were 29% less likely to die prematurely from
any cause than those who never worked out. The lead author of the study noted that
“Reductions in risk were similar in the weekend warriors and the regularly active.”
Gretchen Reynolds, writing in the New York Times, noted that this is good news for
about one-third of Americans who only work out on weekends.

This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel.