FOR IMMEDIATE RELEASE
March 31, 2009
Contact: Donna Krupa
Office: (301) 634-7253
commoff@the-aps.org
As Good As It Gets: Octogenarian Muscles
Don’t Get Stronger With Exercise
Lesson
learned: Start exercising earlier
 BETHESDA,
Md. (Mar. 31, 2009) Octogenarian women were unable to increase muscle
mass after a 3-month weight lifting program targeted at strengthening the
thigh muscle, according to a new study from the Journal of Applied
Physiology. The results are surprising because previous studies have
found resistance training capable of increasing muscle mass, even for people
who are into their 70s. An increase in muscle size translates to an increase
in strength.
Still, the Ball State University study contained some
good news: The octogenarians were able to lift more weight after the
training program, likely because the nervous system became more efficient at
activating and synchronizing muscles.
The American Physiological Society published the
study, “Improvements in whole muscle and myocellular function are limited
with high-intensity resistance training in octogenarian women.” The
researchers are Ulrika Raue, Dustin Slivka, Kiril Minchev and Scott Trappe.
You can read the full study by going to:
http://jap.physiology.org/cgi/reprint/91587.2008v1?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=Trappe%2C+S&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT
Aim: Strengthen Octogenarian Thigh Muscle
The experiment involved six women, all in their 80s,
all of whom lived independently and came to the laboratory three times a
week for three months. The women exercised on a machine designed to
strengthen the thigh (quadriceps) muscle. They did three sets of 10 lifts,
with a 2-minute rest period between sets.
The researchers measured the size of the women’s thigh
muscle using an MRI, before the exercise program began and after it ended.
They also took biopsies from the thigh muscles, which they used to track
muscle changes at the cellular level.
The biopsies included both fast-twitch and slow-twitch
muscle fibers. Fast-twitch muscles are high powered and explosive and are
associated with anaerobic exercise. Slow-twitch are associated with aerobic
tasks, including endurance exercise such as marathons.
Fast-twitch muscles are important in posture and
balance and so may be of particular importance for the elderly, who are more
prone to falls. When people do not use their muscles during a period of
convalescence or with a sedentary lifestyle, the fast twitch muscles lose
functionality and atrophy more quickly than slow-twitch.
From the muscle biopsies, the researchers isolated
single muscle strands, both fast-twitch and slow-twitch. They measured the
strength, speed and power of each fiber and examined the genetic profile of
these strands.
No change in muscle strength
As a result of the exercise program, the octogenarians
were able to increase the amount they could lift with their quadriceps by
26%. That was the good news. The bad news was that the pre- and
post-training MRIs showed that the training did not change their muscle
size. This was surprising because an earlier study had found that
70-year-old women gained 5% muscle mass with resistance training.
The biopsy results confirmed the MRI results: there was
no change in the size of the individual muscle strands, pre-training versus
post-training. This confirms that the increase in the amount the women could
lift with the quadriceps was unrelated to improvement in muscle strength.
Instead, the results were probably due to improvements in how efficiently
the nervous system was able to activate and synchronize the muscles.
In an earlier study, the researchers found that the
muscles of octogenarian men also failed to gain strength with the exercise
program. Together, the studies show that the muscles of octogenarian men and
women are far less responsive to improving with exercise, even compared to
people only 10 years younger.
“The message of the study is that exercise is good for
octogenarians, just not as good as we thought it would be,” Dr. Trappe said.
The study also suggests that it is better to build as much muscle mass as
possible earlier in life to ensure more muscle strength in later life. “We
should do all we can to educate people to build up the muscle before 80,” he
said.
Next steps
Muscle atrophy relates not only to aging, but to people
whose muscles are immobilized for a period and even for astronauts who spend
long periods of time in space. Dr. Trappe, who also does research on
astronauts, next wants to begin to uncover the physiological basis for why
the muscles of octogenarians do not gain strength with resistance exercise.
His team may be able to build on two intriguing
findings from the current study:
-
while the octogenarian women had many fewer muscle fibers,
the fibers they did have were large and healthy looking
-
the genes involved in muscle growth are present in the
resting muscle of the octogenarians at much higher levels compared to
young people.
These results suggest that the octogenarian muscle is
already operating at peak capacity and may not have the potential for better
performance, Dr. Trappe said. If these mechanisms can be understood, it may
be possible to find ways to strengthen older muscles.
Editor’s Notes: To arrange an interview with Dr.
Trappe, please contact Donna Krupa at
commoff@the-aps.org or (301) 634-7253.
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (APS) has been an
integral part of this scientific discovery process since it was established
in 1887.
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