Here's the Minimum Amount of
Exercise You Really Need
April 03, 2015
Story at-a-glance
Women who exercise just a few times a week have a lower risk
of heart disease, stroke, and blood clots
For moderate-exercise activities, the health benefits peaked
at four to six sessions per week
For more strenuous exercise, the health benefits peaked at
just two to three times per week
By Dr. Mercola
Eighty percent of Americans fail to meet the recommended
amount of exercise,
which is 2.5 hours of moderate-intensity activity or 1.25 hours
of vigorous-intensity activity each week… along with twice
weekly
strength-training workouts.1
These are the “official” US government exercise
recommendations, but they are not the last word on fitness. How
much exercise you need depends on a number of factors,
not the least of which is the type of activity you do.
The more intense you work out, the less frequently you should do
it (and the shorter the duration should be).
It’s entirely possible to get a phenomenal workout in just 20
minutes two or three times a week if you’re using, for instance,
high-intensity interval training (HIIT) or super-slow weight
training. But this doesn’t mean you should simply sit around for
the rest of the week.
Regular walking (upwards of 7,000 steps a day) is also
important, in addition to regular exercise. But before
I get into the details, here’s something you should know: even
small amounts of exercise matter… and any amount of
exercise is better than none at all.
The Minimal Amount of Exercise You Should Strive For…
The greatest health gains among exercisers are often seen
when a person goes from not exercising at all to getting
physically active. And it doesn’t take much to see significant
benefits. Compared to women who don’t exercise at all, for
instance, women who exercise just a few times a week have a
lower risk of heart disease, stroke and blood clots.2
For moderate-exercise activities, which included walking,
gardening, and housework, the health benefits peaked at four to
six sessions per week. For more strenuous exercise (defined as
exercise that caused sweating and a fast heartbeat), the
benefits peaked at just two to three times per week.
Those who engaged in the more strenuous exercise two to three
times a week lowered their risk of heart disease, stroke, and
blood clots by 20 percent. Interestingly, less is more in this
case, as women who exercised strenuously more than
three times per week had increased vascular risk.3
It’s quite clear that if you engage in intense exercise,
overdoing it can cause serious problems, which is often seen in
marathon runners. According to a study presented at the Canadian
Cardiovascular Congress 2010 in Montreal, regular exercise
reduces cardiovascular risk by a factor of two or three, but the
extended vigorous exercise performed during a marathon
raises your cardiac risk seven-fold!
Even Minimal Amounts of Exercise May Improve Your Health
Exercise is not “all or nothing” when it comes to your
health. If you don’t fit in three workouts one week, but do just
one instead, you’ll still benefit – albeit not quite as much as
if you had done more. According to researcher Philipe de Souto
Barreto from the University Hospital of Toulouse:4,5
“Getting inactive people to do a little bit of
physical activity, even if they don’t meet the
recommendations, might provide greater population health
gains… Achieving target physical activity recommendations
should remain as a goal but not the core public health
message surrounding physical activity.”
For instance, just one hour of moderate activity a week may
lower your risk of premature death by 15 percent, while just 20
minutes of vigorous intensity once a week may lower it by 23
percent.6
Research also suggests that walking for one to 74 minutes a week
may lower your risk of premature death by 19 percent compared to
those who are sedentary.7
So if you’re feeling intimidated about starting an exercise
program, feeling you simply don’t have enough time… if you can
carve out 20 minutes a week, you can experience some health
benefits of exercise.
That being said, there is a dose-response relationship
between physical activity and premature death as well as at
least seven chronic diseases (cardiovascular disease, stroke,
hypertension, colon cancer, breast cancer, type 2 diabetes, and
osteoporosis).8
In other words, the more exercise you do, the greater the
benefits will be. This is true only to a point, because
once you get past a certain threshold then more exercise will
only cause harm.
Most people are not at risk of over-exercising… but,
as mentioned, the general guideline to remember is the more
intense you exercise, the more recovery time you will need. One
of the many positive aspects of intense exercise is that you can
“max out” your exercise requirements in a very short (and very
achievable) amount of time.
The Benefits of Shorter, More Intense Workouts
When you exercise intensely, you can reap greater rewards in
a shorter period of time. For starters, high-intensity
interval training burns more calories in less time – a mere
2.5 minutes, divided into five 30-second sprint intervals at
maximum exertion, each followed by four minutes of light
pedaling to recuperate, can burn as much as 220 calories.9
Besides burning more calories, HIIT has also been shown to
produce greater health benefits overall than conventional
aerobic training, such as increasing insulin sensitivity and
glucose tolerance – both of which are critical components of
optimal health.
Another important benefit of high-intensity interval training
is its ability to naturally increase your body's production of
human growth hormone (HGH), also known as "the fitness hormone."
HGH is a synergistic, foundational biochemical underpinning
that promotes muscle and effectively burns excessive fat. A
study published in the journal Cell Metabolism even
showed that when healthy but inactive people exercise intensely,
even if the exercise is brief, it produces an immediate
change in their DNA.10
While the underlying genetic code in the muscle remains
unchanged, exercise causes important structural and chemical
changes to the DNA molecules within your muscles. This
contraction-induced gene activation appears to be early events
leading to the genetic reprogramming of muscle for strength, and
to the structural and metabolic benefits of exercise.
Several of the genes affected by an acute bout of intense
exercise are genes involved in fat metabolism. Specifically, the
study suggests that when you exercise, your body almost
immediately experiences genetic activation that increases the
production of fat-busting proteins HIIT also plays an important
part in promoting overall health and longevity. This too is
something you cannot get from conventional, aerobic endurance
training. Other benefits associated with high-intensity interval
training include:
How to Get the Most Exercise Benefits in the Shortest Amount of
Time
The HIIT approach I personally use and recommend is the
Peak Fitness method, which consists of 30 seconds of maximum
effort followed by 90 seconds of recuperation, for a total of
eight repetitions. Super Slow strength training is another
high-intensity exercise, which may even be more effective than
Peak Fitness cardio. While they both are highly effective, you
can generate a higher cardiac output with
Super Slow training as discussed in my interview with Dr.
McGuff.
By slowing your movements down, you're actually turning them
into high intensity exercise. The super-slow movement allows
your muscle, at the microscopic level, to access the maximum
number of cross-bridges between the protein filaments that
produce movement in the muscle. You can perform the super-slow
technique with hand weights, resistance machines, bodyweight
exercises, or resistance bands.
You only need about 12 to 15 minutes of super-slow strength
training once a week to achieve the same HGH production
as you would from 20 minutes of Peak Fitness sprints, which is
why
fitness experts like Dr. Doug McGuff are such avid
proponents of this technique. The key to making this work for
you is intensity, which needs to be high enough that you reach
muscle fatigue. If you've selected the appropriate weight for
your strength and fitness level, your goal is to have enough
weight that you cannot do more than 12 reps, but not so much
that you can't complete at least four. Ideally, you will be
somewhere in the neighborhood of seven to eight.
When the intensity is this high, you can decrease the
frequency of your strength training sessions. In fact, the
higher your fitness level, the less often you should do them. I
also recommend incorporating
Buteyko breathing, which involves breathing only through
your nose while working out. This raises the challenge to
another level. As a guideline, when you start out, allow your
body at least two days to rest, recover, and repair between
high-intensity sessions, and do not exercise the same muscle
groups each time.
As your strength and endurance increases, decrease how
often you do the sessions, as each one is placing greater
stress on your body (provided you keep pushing yourself to the
max). As a rule, avoid doing high-intensity exercises more than
twice or three times a week. You can enjoy other activities on
the off-days, such as swimming, Pilates, yoga, biking,
gardening, or whatever other activities tickle your fancy. I
also encourage you to use a pedometer and walk as much as
possible, ideally 7,000 to 15,000 steps daily.
Not Exercising May Be Worse Than Smoking
If you’re looking for motivation to get moving, consider
this: research shows that inactivity is lined to more than 5
million deaths each year, which is similar to the death toll
taken by smoking.11
Data also suggests that at least twice as many deaths occur due
to a lack of exercise than due to obesity. This is really
astounding, considering one in five US deaths are
associated with obesity. Study author Ulf Ekelund from the
Medical Research Council Epidemiology Unit at the University of
Cambridge told TIME:12
“This is a simple message: just a small amount of
physical activity each day could have substantial health
benefits for people who are physically inactive.”
As stated by Dr. Timothy Church, director of preventive
medicine research at the Pennington Biomedical Research Center
in Baton Rouge, exercise indeed affects your entire body—from
head to toe—in beneficial ways.13
This includes changes in your:
Muscles, which use glucose and ATP for
contraction and movement. Tiny tears in your muscles make
them grow bigger and stronger as they heal. Gaining more
muscle through resistance exercises has many benefits, from
losing excess fat to maintaining healthy bone mass and
preventing age-related muscle loss as you age. The
intensity of your resistance training can achieve a
number of beneficial changes on the molecular, enzymatic,
hormonal, and chemical level in your body.
Lungs. As your muscles call for more
oxygen, your breathing rate increases. The higher your VO2
max—your maximum capacity of oxygen use—the fitter you are.
Heart. Your heart rate increases with
physical activity to supply more oxygenated blood to your
muscles. The fitter you are, the more efficiently your heart
can do this, allowing you to work out longer and harder.
Your blood pressure will also decrease as a result of new
blood vessels forming.
Brain. The increased blood flow also
benefits your brain, allowing it to almost immediately
function better. Exercising regularly also promotes the
growth of new brain cells, boosting your capacity for memory
and learning. A number of neurotransmitters are also
triggered, such as endorphins, serotonin, dopamine,
glutamate, and GABA. Some of these are well-known for their
role in mood control. Exercise, in fact, is one of the most
effective prevention and treatment strategies for
depression.
Joints and Bones. Exercise can place as
much as five or six times more than your body weight on
them. Weight-bearing exercise is one of the most effective
remedies against
osteoporosis, as your bones are very porous and soft,
and as you get older your bones can easily become less dense
and hence, more brittle -- especially if you are inactive.
The simple take-home message is this: if you are currently
living a sedentary lifestyle, the mere act of incorporating some
high-intensity activity two or three days a week, along with
regular walking, can significantly reduce your mortality rate.