What’s the Right Dose of Exercise
for a Longer Life?
May 01, 2015
Story at-a-glance
The “Goldilocks zone” in which exercise produces the
greatest benefit for longevity is between 150-450 minutes of
moderate exercise per week, lowering your risk of early
death by 31 and 39 percent respectively
Exercising more than 450 minutes per week does not seem to
provide any further increase in longevity. In fact,
exercising 25 hours a week or more only provides a 31
percent mortality risk reduction
Incorporating more high-intensity exercises can also boost
longevity, compared to exercising at a consistently moderate
pace
By Dr. Mercola
Modern fitness research offers many potent reminders that
physical activity is one of the best “preventive drugs” for many
common ailments, from psychiatric disorders to heart disease,
diabetes, and
cancer.1
For example, one meta-review2
of 305 randomized controlled trials comparing the effectiveness
of exercise versus drug interventions on mortality outcomes
found “no statistically detectable differences” between exercise
and medications for prediabetes and heart disease!
One of the key health benefits of exercise is that it helps
normalize your glucose, insulin, and leptin levels by optimizing
insulin and leptin receptor sensitivity.
This is one of the most important factors for optimizing your
overall health and preventing chronic disease, and may explain
why exercise is such a potent preventive medicine.
However, as with other medications, there’s the matter of
dosage. Too little, and you won't get much benefit. Too much,
and you could potentially do harm.
For example, extreme endurance cardio, such as
marathon running, actually damages your heart and can negate
the health benefits you'd otherwise reap from a regular fitness
program.
While your heart is indeed designed to work very hard, and
will be strengthened from doing so, it's only designed to do so
intermittently, and for short periods — not for an hour
or more at a time.
Finding the Goldilocks Zone...
As discussed in a recent New York Times article,3
there’s a “Goldilocks zone” in which exercise creates the
greatest benefit for health and longevity:
“Two new, impressively large-scale studies4,5
provide some clarity, suggesting that the ideal dose of
exercise for a long life is a bit more than many of us
currently believe we should get, but less than many of us
might expect.”
In the larger of the two studies,6
data was collected from six large health surveys involving an
impressive 661,000 adults and 14 years’ worth of death records.
Exercise habits ranged from no exercise at all, to 10 times the
recommended amount, or 25 hours per week and over. Among their
findings:
Those who did not exercise had the highest risk of
premature death
Those who exercised but did not meet current exercise
recommendations of 150 minutes of moderate exercise per week
lowered their risk of early death by 20 percent
Those who met the guidelines of 150 minutes per week of
moderate exercise lowered their risk of death by 31 percent
during the 14 year study period, compared to those who did
not exercise
Tripling the recommended amount of exercise had the
greatest benefit. Those who engaged in moderate exercise
such as walking for 450 minutes per week (just over an hour
a day), lowered their risk of premature death by 39 percent,
compared to non-exercisers
Those who exercised at 10 times above the recommended
level only gained the same mortality risk reduction as those
who met the guidelines of 150 minutes per week
The second study7
focused on intensity. Here, health survey data from more than
200,000 adults was pooled, and the exercise that each person
engaged in was qualified according to intensity. As reported in
the featured article:8
“[A]s in the other study, they found that meeting the
exercise guidelines substantially reduced the risk of early
death, even if someone’s exercise was moderate, such as
walking. But if someone engaged in even occasional vigorous
exercise, he or she gained a small but not unimportant
additional reduction in mortality.
Those who spent up to 30 percent of their weekly
exercise time in vigorous activities were 9 percent less
likely to die prematurely than people who exercised for the
same amount of time but always moderately...
[T]hose who spent more than 30 percent of their
exercise time in strenuous activities gained an extra 13
percent reduction in early mortality, compared with people
who never broke much of a sweat.” [Emphasis mine]
Everyone Can Benefit from Walking More Each Day
It’s interesting to note that the greatest benefit, in terms
of longevity, was reaped by those who primarily walked for an
hour or so each day. Overwhelming amounts of research shows that
sitting too much can take a massive toll on your health, and
everyone would benefit from simply standing up and walking more
each day.
Chronic sitting is the new smoking, actually raising your
risk of lung cancer by over 50 percent. Importantly, it elevates
your risk for an early death from poor health independently from
your fitness and other lifestyle habits.
Personally, I believe that application of this truth has had
one of the most profound impacts on my health. I used to sit
more than 12 hours a day and had chronic back pain. Now, I sit
less than one hour a day and my pain has disappeared, posture
has improved, and I feel much better.
It’s ok to sit some, and you don’t have to go under an hour
like I have, but ideally you’ll want to limit your sitting to
three hours or less, and aim for 7,000 to 10,000 steps a day,
over and above your scheduled workout. A
fitness tracker can be a helpful tool to monitor your
progress and ensure you’re hitting your mark.
If you’ve taken such advice to heart and are incorporating
more walking into your day, consider switching up the pace at
regular intervals, interspersing bouts of
speed walking followed by more casual strolling.
In study after study we find that it is this intermittent
high and low intensity that appears to produce the most
significant results. So simply by exerting yourself
intermittently when walking, you can dramatically increase the
return of your effort without spending any extra time on it.
Intermittent High Intensity Is Key for Optimal Results
A growing body of clinical research maintains that the ideal
fitness regimen is one that mimics the
movements of our hunter-gatherer ancestors, which included
short bursts of high-intensity activities, but not
long-distance running such as is required to complete a
marathon.
The idea behind "hunter-gatherer fitness" is to closely emulate
the actions that ancient man took on a daily basis. This is what
your body is hard-wired for, after all, and includes such
attributes as:
A variety of exercises performed regularly (weight
training, cardio, stretching, etc.)
Alternate difficult days with easier days
Interval training sessions performed once or twice a
week
Weight training at least twice a week
Ample time for rest after physical exertion
Part of what makes high-intensity interval training (HIIT) so
beneficial for your body composition and general fitness and
longevity is that it:
Engages far more of your muscle tissue than conventional
aerobic cardio exercise. You have three different types of
muscle fibers: slow, fast, and super-fast. Only ONE of these
muscles, the super-fast fibers, will impact your production
of human growth hormone (HGH, also known as “the fitness
hormone”), which is KEY for strength, health, and longevity,
and HIIT is the only way to effectively engage these
super-fast fibers.
If you're over the age of 30, especially if you lead an
increasingly sedentary lifestyle, you've likely entered a
phase known as somatopause (age-related growth hormone
deficiency). As your HGH levels decrease, your levels of
insulin-like growth factor-1 (IGF-1) also decrease. This is
another important part of what drives your body's aging
process.
Produces anti-inflammatory
myokines in your muscles, which very effectively
reverses metabolic syndrome by increasing all of the
following: insulin sensitivity, glucose utilization inside
the muscle, liberation, and burning of fat from adipose
cells. Myokines also act as chemical messengers that inhibit
the release and the effect of the inflammatory cytokines
produced by your body fat. They also significantly, via an
inhibitory effect, reduce body fat irrespective of calorie
intake!
Sample HIIT Demonstration
There are many ways to do high-intensity interval exercises.
You can use a bicycle, an elliptical machine or treadmill,
sprint outdoors, or up the intensity on your strength training
routine by slowing it down (super-slow
strength training). Just beware that if you sprint outside,
you need to properly
stretch prior to sprinting to avoid being sidelined by an
injury.
Also, unless you are already an athlete, I would advise
against sprinting outdoors, as several people I know became
injured doing it the first time. For a demonstration using an
elliptical machine, please see the video above. Here are the
core principles:
Warm up for three minutes
Exercise as hard and fast as you can for 30 seconds. You
should be gasping for breath and feel like you couldn't
possibly go on another few seconds. It is better to use
lower resistance and higher repetitions to increase your
heart rate
Recover for 90 seconds, still moving, but at slower pace
and decreased resistance
Repeat the high-intensity exercise and recovery 7 more
times. (When you're first starting out, depending on your
level of fitness, you may only be able to do two or
three repetitions of the high-intensity intervals. As
you get fitter, just keep adding repetitions until you're
doing eight during your 20-minute session)
Cool down for a few minutes afterward by cutting down
your intensity by 50-80 percent
Be mindful of your current fitness level and don't overdo it
when you first start out. Also keep in mind that there's no
"magical" speed here. It's entirely individual, based on your
current level of fitness. Some may reach their anabolic
threshold by walking at a quick pace, while others may need to
perform a mad-dash to get the same effect.
Also remember that besides intensity, recovery is a
key factor of high intensity workouts. An equation to
keep in mind is that as intensity increases, frequency can be
diminished. In fact, you need to allow your body to
fully recuperate in between sessions, so it's NOT recommended to
do high-intensity exercises more than three times a week. Both
Phil Campbell and
Dr. Doug McGuff have addressed this in previous interviews.
Balanced Variety Is the Key to Optimal Health and Longevity
Even if you're eating the best diet in the world, you still
need to exercise effectively to reach your highest level of
health. I've often equated exercise to a drug from the
perspective that they both need to be taken at optimal dosage to
reap the desired effect.
As for the optimal weekly time investment, remember that the
greatest effect on longevity was found among those who engaged
in 150-450 minutes of exercise per week, the bulk of which was
moderate intensity activities such as walking. And those who
included bouts of vigorous activity also got an extra boost in
longevity, compared to those who kept to a one pace.
Ideally, you want to incorporate a variety of activities,
including core-strengthening exercises, strength training,
stretching, and high-intensity activities into your rotation.
High-intensity interval training boosts human growth hormone
(HGH) production, which is essential for optimal health,
strength, vigor, and yes—longevity. That said,
intermittent movement is equally (if not more) critical for
maximizing the quality of your life. Chronic, undisrupted
sitting—even if you maintain an optimum fitness program—has been
found to be an independent risk factor for premature
death.
In short, one of the keys to optimal health is to remain as
active as you can, all day long. Whenever you have a chance to
move and stretch your body in the course of going about your
day, do so. That said, there’s no doubt that an ideal fitness
regimen requires a little more effort. Fortunately, you can
accomplish the bulk of it through high intensity exercises,
which require a minimal time investment—as little as 20 minutes,
two to three times a week.