August 1, 2008
Table of Contents
- Sarcopenia (Introduction to special issue)
- A Loss of
Muscle, Strength, and Function (Understanding sarcopenia)
Until recent years, most
dictionaries and reference works did not even include the word
sarcopenia. Yet most senior fitness professionals today are acutely
aware of the term. Let us take a closer look at its etymology,
definition, and implications.
A Loss of Muscle, Strength, and
Sarc, and sarco,
derive from the Greek form sarko, meaning flesh. The suffix -penia
traces back to New Latin which, in turn, stems from the Greek penia,
meaning poverty or lack. Modern authors describe sarcopenia not only as
an age-related deficit of skeletal muscle mass, but also as an
accompanying loss of muscular strength and function. These factors
intertwine in several respects:
- Loss of muscle mass is associated
with loss of strength.
- Loss of strength is associated
with loss of muscular function.
- Loss of muscle mass and strength
is associated with deteriorating general health.
- Loss of muscle mass and function
is associated with the progression of disease and with eventual
Variables other than physical
inactivity (such as hormonal changes and suppressed protein synthesis)
may play a role in the development of sarcopenia. However, adopting a
sedentary lifestyle is a major contributor to the condition -- and one
that individuals can readily address. Indeed, sarcopenia is partially
reversible given effective exercise training.
As mentioned above, sarcopenia is more than simple muscle loss.
Furthermore, it should not be confused with disease-related declines in
muscle mass. For example, sarcopenia differs from wasting, which
depletes both muscle and adipose tissue consequent to the insufficient
dietary intake resulting from certain diseases. Conversely, sarcopenia
can appear in individuals unaffected by other conditions that
characteristically lead to muscle loss.
Instead, sarcopenia typically arises during the fourth decade of life,
accelerates after the age of 50, and may advance even more rapidly after
the approximate age of 75. With normal aging -- and even more
dramatically with inactive aging -- there is a decline in the number of
motor neurons that control muscular action. Skeletal muscle fibers that
are subject to those nerve cells can atrophy and ultimately die, thereby
reducing muscle mass. Predominantly, atrophy has been observed to occur
in fast twitch fibers (used for high-intensity movement). When a fast
twitch motor neuron expires, a neighboring slow twitch motor neuron may
step in to serve the affected muscle fibers, which will forestall
atrophy. However, such remodeled motor units can be predicted to produce
less force, slower movement, and decreased movement control. Reductions
in balance and movement speed indicate a need for safety awareness
during fitness training activities undertaken to counter sarcopenia.
Another source of muscle loss in sarcopenia is an age-related slow-down
in muscle-protein synthesis. Synthesis rates are 30 percent lower in
seniors compared to young adults. Clearly, this decrease in
muscle-protein synthesis leads to reductions in muscle mass. Moreover,
satellite cells situated in the basal membranes of the muscle cells also
decrease in number with age. This is important because those helper
cells are essential for the growth and regeneration of new skeletal
muscle tissue. In other words, their scarcity may help to explain
diminished muscle mass. More bluntly, this also points to the
requirement for vigilant safety care and gradual progression practices
in resistance training programs for older adults. With age, the
capability of muscle to regenerate after overload -- and, significantly,
after injury -- decreases.
Age-related declines in the levels and concentrations of specific
hormones have been linked to the development of sarcopenia. Meanwhile,
compromised cardiovascular health may lead to the reduced oxygen and
fuel perfusion of skeletal muscles, thus promoting sarcopenia. Fitness
trainers can exert a positive impact on vascular delivery by
implementing balanced exercise prescriptions that include activities
designed to prevent or mitigate cardiovascular disease.
In addition, nutritional inadequacy may play a role in sarcopenia.
Malnutrition appears to shrink muscle mass more drastically in elders
than it does in the young. Among women ages 65-plus, approximately 25
percent are believed to follow diets deficient in protein. These
circumstances suggest a useful role for health-fitness professionals in
terms of providing nutrition education to their older adult clients.
A most promising -- and the most obvious -- intervention in the battle
against sarcopenia is safe and effective strength training. Although
sarcopenia cannot be entirely prevented by physical activity, it is
present to a lesser degree in physically active seniors. Losses in
muscle mass and strength correspond to losses in functional measures
involving balance, gait speed, stair-climbing speed and power, and
sit-to-stand activity. Impaired functional performance is a reliable
predictor of impending disability requiring long-term care
institutionalization. Likewise, diminished muscle strength is a sound
predictor of all-cause mortality in the elderly.
The benefits of exercise training with regard to the management of
sarcopenia can encompass:
- Increased skeletal muscle mass;
- Increased muscular strength and
- Enhanced function, including
improved balance with lower risk of falling and bone fracture;
- Reduced risk and/or progression
- Greater and prolonged personal
- Higher quality of life.
As previously noted, it is vital that
older adult strength training programs incorporate effective safety
precautions. Even so, progressive muscular overload is precisely what is
needed to check the development of sarcopenia. Senior fitness
professionals must conduct individualized plans that establish the right
balance of healthful challenge and sensible conservatism. Begin by
obtaining medical clearance for older clients to participate in strength
training activity. Observe an initial 8-week adjustment period using
minimal resistance, to be followed by gradual progression. In other
words, start low and go slow. Educate clients as to the principle
of gradual progression, as well as to proper training mechanics,
technique, and body alignment. Follow American Senior Fitness
Association guidelines for older adult resistance training. In addition,
below are some special tips for instituting a muscular strength program
to effectively fight sarcopenia:
- Conduct approximately 8 to 10
exercises that work all of the major muscle groups. Stay within
approximately 10 to 15 repetitions, with the goal of producing a
rating of perceived exertion of "somewhat hard" (in the 12 to 13
range on Borg's RPE scale). Begin with 1 set of each exercise,
although it is acceptable eventually to progress to performing 2 or
3 sets (that is, gradually over time and only as is well tolerated).
To progress, first increase repetitions to their higher range. Then
increase resistance (in small increments) with an attendant
reduction of repetitions.
- A good schedule for strength
training is twice per week with a recovery period of at least 48
hours between workouts. Adequate recovery time is critical in light
of the protein synthesis issues discussed above. If two sessions per
week are not well tolerated (or cannot be scheduled for other
reasons), it may still be beneficial to complete one session per
- Try to limit senior strength
workout session lengths to approximately 20 to 30 minutes. Sessions
lasting longer than 60 minutes can discourage long-term exercise
adherence and may increase the risk of accidental injury or undue
strain. For reasons explained above, steps to avoid injury and
overuse must always be meticulously enacted.
- Try to include more multi-joint
than single-joint movements.
- Stick with concentric, as opposed
to eccentric, muscle work.
- Complete thorough warm-up,
cool-down, and stretching activities.
- Follow established guidelines
regarding exercise slow-down and cessation signs, as well as events
requiring immediate medical attention. If any existing health
condition is observed to be deteriorating, immediate medical
consultation is needed because this is likely to pose an exercise
- When safe and practical, balance
and muscle coordination can be promoted by having seniors perform
some of their strength exercises in a standing position while using
resistance bands or free weights such as dumbbells.
- Omit strength training for
participants with arthritis (and those with other joint or bone
disorders) during periods when they are experiencing pain or
- Remind participants never to hold
their breath during strength training.
- Teach participants to work with
controlled joint movements (which includes working at an appropriate
speed of movement).
- Teach participants to work within
their own personal "pain-free" range of motion.
- After an interruption in a
participant's training regimen, resume strength training at an
intensity level approximately half (or less) that of the previous
Morgenthal, AP and Shephard, RJ.
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aging. Champaign IL: Human Kinetics.
Vella, C and Kravitz, L. Sarcopenia: The mystery of muscle loss. http://www.unm.edu/~lkravitz/Article%20folder/sarcopenia.html.
July 30, 2008.
Welch, GL. (2005). Screening and fitness assessment. In Bryant, CX and
Green, DJ (Eds.), Exercise for older adults: ACE's guide for fitness
professionals (2nd ed.). San Diego: American Council on Exercise.
Zacker, RJ. (2006). Health-related implications and management of
sarcopenia. Journal of the American Academy of Physicians
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