At age 77, Mirkin is a true inspiration. He and his wife regularly ride 30-60 miles on their tandem.
There have been some articles in respected research publications recently that suggest that intense endurance training may be harmful to the hearts of aging athletes. In his last e-Zine, Dr. Mirkin addresses this issue(see below), and concludes that the risk of inactivity is far greater than the risks of activity, even intense activity. You can subscribe to the e-Zine here.
At age 70, I am especially interested in this subject. I ride between 150-200 miles per week, and work out twice per week with weights. Next year, I have joined the Ultra Marathon Cycling Association's year-rounder program. My goal is to ride at least one 90-140 mile ride per month and accumulate 1500 miles or more with long distance rides. My yearly goal is 8,000 miles or more. Am I harming my health?
Below is the article I refer to from Dr. Gabe Mirkin's Fitness and Health e-Zine
December 9, 2012:
Healthy Older People Can and Should Compete in Endurance Events An editorial in the January 2013 British medical journal,
Heart, states that "Running too fast, too far, and for too many
years may speed one's progress toward the finish line of life."
The author bases his opinion on two recent reports presented at
* DISTANCE: One study of 52,600 people followed for 30 years
showed that runners had a 19 percent lower death rate than non
runners, but those who ran more than 25 miles a week did not live
longer than non-runners.
* SPEED: Another study showed that runners who ran slower than
eight miles per hour lived longer than non-runners, but those who
ran faster than 8 MPH did not live longer.
These two studies are far too limited to make you think that
older people should limit how much and how intensely they
exercise. THEY APPEAR TO SHOW THAT INTENSE OLDER RUNNERS DO NOT
GAIN AN ADVANTAGE OVER NON-RUNNERS. THEY DO NOT SHOW THAT RUNNING
IS HARMING THEM. No reasonable physician should use just this
data to recommend limiting exercise in older people. Overwhelming
evidence shows that exercise helps prevent and treat obesity, high
blood pressure, diabetes, heart attacks, strokes, and certain
cancers, and helps to prolong life.
I am 77 years old and ride a bicycle more than 200 miles per
week, race three times a week at 20 MPH, do interval training once
a week, and lift weights seven days a week. I have no plans to
change my training.
James H. O'Keefe, a cardiologist in Kansas City who was an
elite triathlon athlete, summarizes his concerns about older
people exercising far and fast (Mayo Clinic Proceedings (June
2012;87(6):587-595). He believes that too much exercise damages
the heart and arteries by:
1) causing heart muscle to release enzymes (troponin and B-type
natriuretic peptide) into the bloodstream, a sign of heart damage.
2) scarring the heart muscle
3) increasing calcium plaques in the large arteries
4) causing irregular heartbeats, in particular atrial
He is concerned about these findings in spite of the fact
that he has no data to show that older exercisers are harmed by
these changes. Overwhelming data show that exercisers have lower
rates of disability and death (Arch Intern Med, 2008;168(15):1638-1646),
and are healthier and live more than seven years longer than
non-exercisers (Med Sci Sports Exerc., 1993;25(2):237-244).
REFUTING HIS ARGUMENTS COLLECTIVELY: The apparent heart
damage is the same type of muscle damage that is seen in the
skeletal muscles of trained athletes. Here is why these changes
are as beneficial to the heart muscle as they are to the skeletal
Every serious athlete learns that all training is done by
"stressing and recovering". IF YOU WANT TO MAKE A MUSCLE STRONGER,
YOU HAVE TO EXERCISE SO INTENSELY THAT YOU DAMAGE THAT MUSCLE.
Then when the muscle heals, it is stronger than before it was
damaged. So, knowledgeable athletes:
* Take a hard workout that damages their skeletal muscles. They
know this because they feel burning during exercise, and soreness
in their muscles eight to 24 hours after this intense workout.
* Then they take less intense workouts for as many days as it
takes for the muscles to heal and the soreness to go away. If they
do not take easier workouts on the days when their muscles are
sore, they often injure themselves.
So workouts for knowledgeable athletes in all sports
typically alternate one or more days of intense workouts with as
many easy workouts as needed to allow recovery.
REFUTING EACH POINT INDIVIDUALLY:
1) HEART MUSCLE RELEASES ENZYMES (TROPONIN AND B-TYPE
NATRIURETIC PEPTIDE) INTO THE BLOODSTREAM, A SIGN OF HEART DAMAGE:
This is the training effect that you expect from proper exercise
training. If you don't "damage" a skeletal muscle, it will not
become stronger. If you don't "damage" the heart muscle, it will
not become stronger. These enzymes that leak from the heart muscle
into the bloodstream return to normal in less than a week, in the
same manner that enzymes from damaged skeletal muscles return to
normal in the same amount of time.
2) SCARRING OF THE HEART MUSCLE: The "scarring" of heart
muscle is the same as the scarring in skeletal muscles. It
disappears after the muscle heals and is necessary for muscles to
become stronger. (Refer to the parts of muscles in the picture at
muscles are composed of thousands of muscle fibers. Each fiber is
a long rope made up of a series of thousands of similar blocks
called sarcomeres, lined end to end to form a long chain. Each
block attaches to the next sarcomere at the "Z line". Muscles
function by shortening a little bit at each of the thousands of "Z
lines". The "Z lines" all shorten simultaneously and the entire
muscle then can contract. The "Z lines" are where muscles are
damaged. It is damage to these "Z lines that causes muscle growth
after healing, which makes muscles stronger.
3) INCREASED CALCIUM PLAQUES IN THE LARGE ARTERIES: Plaques
in arteries may have more to do with the diet of endurance
athletes than their exercise programs. High mileage athletes burn
far more calories each day than do casual exercisers. Therefore,
they have to eat far more food in order to have the energy to
power their muscles during training. The extra food that athletes
eat is likely to contain far more saturated fat, sugar, high
glycemic-load foods, red meat, sugared drinks, and calories. All
of these food components can increase the formation of plaques in
arteries. Therefore, it is probably the increased intake of
plaque- forming foods, and not the extra mileage, that may negate
some of the benefits of long and hard exercise. Athletes who eat
huge amounts of food and restrict these unhealthful components
should have almost no plaques at all. I think that future studies
will demonstrate that the increased deposition of plaques has
nothing to do with running more miles or faster miles.
4) IRREGULAR HEART BEATS, IN PARTICULAR ATRIAL FIBRILLATION:
At this time, we do not know if there really is an increased risk
for irregular heartbeats in endurance athletes. All we know is
that older competitive athletes suffer from irregular heartbeats
just as younger athletes and non-athletes do. Furthermore, we
have no evidence that older athletes are at increased risk for the
harmful side effects of irregular heartbeats: fainting, accidents
or sudden death.
The main concern about atrial fibrillation is that the
patients are at increased risk for clotting in general and strokes
in particular. However, nobody has shown that older endurance
athletes with atrial fibrillation are at increased risk for
clotting or strokes.
Dr. O'Keefe himself writes: "Sudden cardiac death among
marathoners is very rare, with one event per 100,000
participants." Here are two of his references: Med Sci Sports
Exerc. 2012;44(6):990-994; N Engl J Med . 2012;366(2):130-140.
BENEFITS OF ENDURANCE EXERCISE IN ALL AGE GROUPS: Dr
O'Keefe is completely honest and reasonable in listing the
following ways exercise helps to prevent and treat heart attacks:
* Increases the good HDL cholesterol
* lowers triglycerides
* treats obesity
* lowers high blood pressure
* Improves insulin sensitivity
* lowers blood sugar
* strengthens arteries
* helps with smoking cessation
* reduces psychological stress
* lowers hematocrit and blood viscosity
* expands blood volume
* prevents clotting
* increases blood flow to the heart
* increases collateral circulation to the heart
* increases tolerance of decreased blood flow to the heart
* reduces atherosclerosis
* enlarges arteries leading to the heart
* reduces major sickness and death
MY LAST WORD ON THE SUBJECT: I am 77 years old and plan to
continue riding my bicycle 200 miles a week.
Note: I have sent this to the Wall Street Journal in
response to their article, "One Running Shoe in the Grave",
November 27, 2012.