Low Protein + Low Exercise = Sarcopenia
Sar-co-PEE-nee-ah. It starts to set in around age
45, when muscle mass begins to decline at a rate of about 1 percent per year.
This gradual loss has been tied to protein deficiency, lack of exercise, and increased
frailty among the elderly.
Physician Carmen Sceppa (seated) and exercise physiologist
Jennifer Layne examine a digital image of skeletal muscle to assess sarcopenia.
Researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging
at Tufts University (HNRCA) in Boston, Massachusetts, have been studying the
various factors involved in sarcopenia since 1988. The work is conducted at
the centers Nutrition, Exercise Physiology, and Sarcopenia Laboratory
(NEPS), led by acting director Carmen Castaneda Sceppa, a physician specializing
in nutrition. There, the researchers use a variety of study designs to discern
factors such as nutrition, hormones, and immune responses that influence loss
of muscle mass.
The NEPS laboratorys researchers have repeatedly shown the safety and
effectiveness of resistance, or strength, training in reversing sarcopenia and
frailty in the elderly. A NEPS study published last year, for example, showed
that a home-based exercise program improved functional performance and balance
in 70 participants aged 70 or older.
Such strong findings come at a time of increased emphasis on exercise. The
recently released 2005 Dietary Guidelines for Americans strongly emphasize the
importance of physical activity and diet in health promotion and place much
greater emphasis on exercise than in the past. The Institute of Medicine (IOM)
added exercise recommendations to its dietary adviceessentially doubling
the Surgeon Generals 1996 recommendation for moderate physical activity,
from 1/2 to 1 hour daily. Moderate physical activity refers to movement
such as walking, gardening, or bicycling.
Strong Living Program regional coordinator Ronnie Friedman
(center) leads an exercise class at the Westminster West Congregational
Church in Westminster, Vermont.
While 60 minutes of activity a day positively affects energy balance
and weight maintenance, at least 30 minutes of moderate physical activity on
most days will reduce the risk of chronic disease, said nutrition professor
and researcher Janet C. King, who headed the 2005 Dietary Guidelines Advisory
Committee. We want the public to understand that any exercise is beneficial
and not give up.
The laboratorys researchers are also conducting studies to examine how
exercise affects chronic degenerative conditions such as diabetes, kidney disease,
and arthritis. Its important to understand how resistance training
helps maintain or improve muscle mass in the presence or absence of chronic
diseases, says Castaneda Sceppa.
Protein Requirements for Older Adults
In the search for new methods to prevent and reverse muscle loss, the researchers
are reassessing the adult dietary protein requirement. Currently, the recommended
daily intake is 0.8 grams per kilogram of body weight, or 56 grams for a 154-pound
male. (To view the protein content of various foods, go to www.nal.usda.gov/fnic/foodcomp.)
The human body reacts to protein deficiency by taking amino acids (the building
blocks of proteins) away from muscle tissue and other areas of the body. The
process, in which the body basically metabolizes itself, is called catabolism
and leads to muscle loss and weakness.
Castaneda Sceppa and colleagues are now studying whether the most healthful
amount of dietary protein differs with age. They are examining the protein intakes
of several elderly men and comparing them to those of younger men.
In another study, the scientists are using 28 days of bed rest to mimic the
effects on muscle mass that occur in astronauts during space flight and in others
from muscle disuse or a sedentary lifestyle. They are looking at whether exercise,
combined with a protein supplement, can counteract the effects of muscle loss
under those conditions.
CT scan of a thigh muscle of a healthy young adult. The
thigh bone is white. The muscle area (yellow) is not indicative of sarcopenia.
When Dietary Protein Isnt Enough
Protein-restricted diets are sometimes recommended because of certain health
conditions in which excess nitrogen may not be adequately excreted through urine.
But there are risks involved for those consuming insufficient protein. While
the low-protein diet may help those with chronic kidney and liver insufficiency,
for example, it is known to lead to muscle loss.
Last year, the NEPS researchers reported on a study involving a group of volunteers
with chronic kidney disease who consumed a low-protein diet. About half the
group engaged in resistance training, while the other half served as a control
Among the strength-trained participantswho exercised for 45 minutes (including
warm-up and cool-down) three times per week for 12 weeksmeasurements taken
before and after the study period showed that, on average, total muscle fiber
increased by 32 percent, and muscle strength increased by 30 percent. Those
who did not exercise lost on average about 3 percent of their body weight, or
about 9 pounds, says Castaneda Sceppa.
In addition, when compared to the control group, the exercisers reduced their
blood levels of two key inflammation factors. That result is tied to better
nutrition and functional capacity.
CT scan of a thigh muscle of a sedentary older adult.
The thigh bone is white. The greatly reduced muscle area (yellow) indicates
Linking Research With Public Health
In 1995, HNRCA researchers started a grass-roots initiative to provide community-based
exercise to older adults at little or no cost to participants. The program was
inspired by studies at the NEPS laboratory that had revealed startling results:
some of the volunteers older than 60 had doubled their leg strength and some
older than 90 had put down their walking canes.
This improved body strength, the opposite effect of normal aging, was having
a positive effect on activities of daily living. As participants reclaimed their
muscles, they also regained their ability to climb stairs, clean house, grocery
shop, and do other activities.
The initiative, called the Tufts Strong Living Program, started as a pilot
program by HNRCA senior exercise physiologist Jennifer Layne. Layne is now a
doctoral student working with Castaneda Sceppa. Older adults need strength
training to keep their muscle mass and their bone density, says Layne,
who is a certified strength-and-conditioning specialist. But exercise
can also help reduce the risk and symptoms of many chronic diseases, such as
arthritis, coronary artery disease, diabetes, frailty, obesity, and osteoporosis.
We also know there are physiological and emotional benefits.
Local Strong Living Programs consist of a 12-week core class that meets on
an ongoing basis. This allows participants the opportunity to exercise year
round as part of a group with a trained instructor.
All program leaders must complete a daylong interactive training workshop led
by Layne and the Tufts Strong Living team, and complete an exam to become certified
to teach classes. Each leader receives a 136-page custom program manual with
detailed step-by step instruction on how to start, teach, and evaluate the program.
Program leaders range from allied health professionals, including nurses and
physical therapistswho offer the program at hospitals and outpatient clinicsto
volunteer peer leaders who teach the program at local community centers, town
halls, and churches.
As part of the Strong Living Program, exercise physiologist
Jennifer Layne (middle) and program coordinator Charlotte Mallio test
a volunteer's muscle strength in the Nutrition, Exercise Physiology, and
Layne works as a team with Castaneda Sceppa and coordinating staff assistant
Charlotte Mallio to manage the Strong Living Program. They collaborate with
participating states departments of public health and elder-care services,
which provide a mix of funding, space, and personnel. We have an application-and-assessment
process that ensures the quality and safety of the program and its leaders.
And each exercising participants functional and health status is assessed
before enrollment, she says.
Layne has trained more than 350 leaders in the past 4 years. The program has
been conducted in 3 states at more than 90 different locations. Each class session
runs for about 1 hour and is attended by 10 to 12 participants on average. Latest
statistics show a total enrollment to date of more than 3,000 participants,
who range in age from 50 to 98 and average age 72.
As people age, there is a large shift in their balance, agility, and
body awareness, says Layne. These classes provide strength, balance,
and flexibility exercises. Leaders use an Exercise Intensity Scale
to determine the appropriate starting weight for each participant. The exercises
are performed using low-cost equipment, such as ankle weights and dumbbells.
They are designed to accommodate older adults with a wide range of abilities,
who exercise in a group setting.
Exercise Versus Activity
Exercise is, by definition, different from the moderate physical activity recommended
by the 2002 IOM guidelines.
An important difference, Layne explains, between physical activity and exercise
is that strength training requires explicit skills and knowledge to perform.
Instruction from a trained individual is important, particularly for older
adults, she says. Exercise is designed to improve the five key components
of physical fitness: cardio-respiratory endurance, muscle strength, muscle endurance,
flexibility, and body composition.
Overall, Strong Living Program successes include a 25-percent increase in lower-body
function and a 32-percent increase in balance.
This year, a special group of participants with a joint disease, osteoarthritis,
were tracked. Their balance improved by 55 percent, and muscle strength increased
by 14 percent after a single 12-week program. Their flexibility improved by
17 percent, and their self-reported pain decreased by 30 percent.
Progress is tracked through overall program surveys and individual participants
physical function assessments. Communication is maintained through data collection
and regular newsletter mailings, which are coordinated by Mallio. Promotion
and recruitment for the program are through word-of-mouth. The demand
is so great that we have a waiting list for participants who want to enroll
and for leaders who want certification training, says Layne.
The HNRCA team has set a goal to expand the Strong Living Program to every
state. To find out more, call or write Layne using the contact information below.By
Rosalie Marion Bliss,
Agricultural Research Service Information Staff.
This research is part of Human Nutrition, an ARS National Program (#107)
described on the World Wide Web at www.nps.ars.usda.gov.
Carmen Castaneda Sceppa and
Jennifer Layne are with the Nutrition,
Exercise Physiology, and Sarcopenia Laboratory, Jean
Mayer USDA Human Nutrition Research Center on Aging at Tufts University,
711 Washington St., Boston, MA 02111; phone (617) 556-3081 [Sceppa], (617) 556-3329
[Layne], fax (617) 556-3083.
"Low Protein + Low Exercise = Sarcopenia" was published in
the May 2005
issue of Agricultural Research magazine.