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gonadotropin on muscle strength and physical function and activity in older men with partial age-related
androgen deficiency. J Clin Endo Metab 2002;87:31253135.
over 80 years.3 It has been estimated that a 10% reduction in the prevalence of sarcopenia in the United States
could save more than $1 billion per year.4 Resistance
training is effective at counteracting sarcopenia, as is testosterone administration.2 However, concerns about the
latter’s adverse effects have led to interest in other, safer
interventions, with creatine supplementation of major interest. Given the prevalence of sarcopenia, and an aging
population, this article will review the available evidence
on creatine supplementation to reduce age-related loss of
muscle mass and strength.
12. Lijesen GK, et al. The effect of human chorionic gonadotropin (HCG) in the treatment of obesity by means of
the Simeons therapy: A criteria-based meta-analysis. Br J Clin Pharmacol 1995;40:237-243.
13. Stein MR, et al. Ineffectiveness of human chorionic
gonadotropin in weight reduction: A double-blind study.
Am J Clin Nutr 1976;29:940-948.
14. Shetty KR, Kalkhoff RK. Human chorionic gonadotropin (HCG) treatment of obesity. Arch Intern Med
1977;137:151-155.
Background
Creatine is synthesized in the body from the amino
acids arginine, glycine, and methionine. Adults generally
make 1-2 g of creatine daily, which is later broken down
to creatinine and excreted at a rate of about 2 g per day.2
To provide for additional needs, creatine can be obtained
from the diet, especially from meat and seafood.3
After synthesis or ingestion, creatine is transported primarily to skeletal muscle where about 95% of the body’s
creatine is stored. About two-thirds of the creatine in skeletal muscle exists as creatine phosphate (CP), with the
remainder found as free creatine.1 As muscles work, CP is
used to replenish adenosine triphosphate (ATP) (see Figure). ATP is the muscle’s biochemical energy molecule
and is converted to ADP as its energy is used. Muscles
normally store enough ATP for only a few seconds of exertion, after which CP can provide fuel for an additional
4-6 seconds of intense exercise. This all depends on the
muscle’s free creatine concentration. Hence, it has been
hypothesized that if supplementation increased the muscle’s creatine levels, more energy would be available during exercise.
15. Bosch B, et al. Human chorionic gonadotrophin and
weight loss. A double-blind, placebo-controlled trial. S Afr Med J 1990;77:185-159.
Creatine and Age-Related
Loss of Muscle Mass and
Strength
By Dónal P. O'Mathúna, PhD
Senior Lecturer in Ethics, Decision-Making & Evidence,
School of Nursing & Human Sciences, Dublin City
University, Ireland
Dr. OMathúna reports no financial relationships relevant to this field of study.
C
reatine remains one of the most popular supplements
for athletes, especially to enhance power and speed.
A large body of research evidence supports claims that
creatine enhances power output during short maximal
bursts of exercise, such as power lifting or sprinting.1 The
benefits are noted particularly when short exertions are
repeated intermittently in what is called interval training.
However, some benefits also have been found for endurance exercise.
Although much of the focus on creatine has been on
athletes, maintaining muscle mass and strength is also
important for older adults. Aging is associated with loss
of muscle mass and decreased strength, which can negatively impact activities of daily living and quality of life.2
Such changes can increase the risk of falls, which can be
a major problem with aging.
Sarcopenia refers to a condition that occurs when fatfree mass is more than two standard deviations below
normal.3 Approximately 25% of those older than 70 years
of age have sarcopenia, increasing to nearly half of those
Alternative Medicine Alert
Figure
ATP
Contraction
ADP + Pi
Creatine
Phosphate
Creatine
+ Pi
17
Table
Biomarker
% increase
in subjects 18-36 years
% increase
in subjects
52-79 years
Total creatine
21.7
14.9
CP
13.3
8.2
Free creatine
39.3
28.6
ATP
4.2
6.8
Mechanism of Action
Muscle mass and strength decrease by about 1-2% per
year after age 50.3 The number of muscle fibers decreases,
but especially type II (or fast-twitch) fibers, which are replaced by intramuscular fat.4 Type II fibers are particularly high in creatine and CP content. Thus, normal aging
and muscle loss reduces stored creatine levels, leaving
less energy available for exercise.
Creatine supplementation in older adults is thought
to increase creatine and CP levels in muscles, allowing
people to exercise longer and at higher intensities, thus
stimulating growth in muscle mass and strength. Changes
in these physiological parameters have been measured in
several studies of both younger and older subjects after
creatine supplementation. The results of a meta-analysis
of such studies are presented in the Table showing how
creatine supplementation impacts these biomarkers.4
Clinical Studies
Creatine was first identified in 1832 and its metabolism was studied extensively over the next century.2 Subsequently, interest faded until the British sprinter, Linford
Cristie, revealed in 1992 that he had taken creatine during
the preparations that led up to his Olympic gold medal.2
Shortly afterwards, studies demonstrated that creatine
supplements did increase muscle creatine levels and exercise performance.5 Since then, several hundred studies
have been published on the topic.2 Much of the interest
in creatine for older adults is derived from extrapolations
from the sports science research.
The first double-blind study to examine creatine use
with resistance training in elderly, sedentary adults was
published in 1998.6 Thirty-two men and women (67-80
years old) were randomized into four groups: creatine
with resistance training, placebo with training, creatine
without training, and placebo without training. None of
the participants did weight-lifting before the study, and all
were sedentary-to-moderately active. Creatine dose was
20 g/day for 5 days, followed by 3 g/day for a total of 8
weeks. Resistance training was carried out three times a
18
week. No significant changes in body mass or body fat
were found in any group. Training groups had significantly increased strength and endurance compared to those
not training (P < 0.02). Creatine supplementation did not
provide any additional benefit.
Three reviews have recently been published and identified a total of 12 relevant trials.2-4 All 12 studies were randomized, placebo-controlled, and double-blinded. They
were similar in enrolling around 20-40 subjects older
than age 65 years and either used a creatine protocol similar to that described above or gave subjects 5 g/day for a
number of months. The longest study, which lasted 1 year,
reported no significant differences between its groups.7
Out of the 12 studies, seven found significant beneficial
effects on fat-free muscle mass and/or strength, and five
found no beneficial effects on muscle mass or strength.
The results of all these studies have not been combined
into a meta-analysis. Most studies giving creatine supplements without exercise found beneficial effects on muscle
mass and strength, but some found no benefits. About half
the studies included resistance training programs, again
with the majority showing significant benefits, but some
not. All of the reviews concluded that creatine supplementation, particularly with resistance training, can have
beneficial effects on muscle wasting in older men and
women. However, the effects are not consistent, suggesting that other variables need to be considered. Since resistance training itself is known to have beneficial effects,
most reviewers recommend combining creatine supplements with exercise.
Some studies have examined the timing of creatine ingestion and suggested that this may be more important
than the actual dose of creatine.8 Exercise stimulates muscle protein degradation and synthesis. Synthesis predominates when protein or amino acids are ingested shortly
before or after exercise, hence the current popularity of
protein shakes being consumed by athletes immediately
after workouts. Part of the reason for these effects is increased blood flow to muscles after exercise. This has
been hypothesized as a way to more efficiently transport
ingested creatine to muscles. A small number of studies
have found that ingesting creatine immediately before
and after exercise leads to greater gains in muscle mass
than when creatine is ingested in the morning and evening, away from training times.3
Adverse Effects
Creatine supplementation among athletes frequently
leads to a 1-3 kg weight gain, probably due to intramuscular water retention.9 Concerns often are raised about
cramping when creatine is taken in conjunction with exercise, although this has not been supported by studies.1
Anecdotal reports claim creatine supplementation can
February 2012
cause gastrointestinal problems, though these are not
frequently reported in studies. One study with older men
found significantly more reports of loose stools during
creatine loading than with placebo, and during maintenance dosing, more muscle cramping and strains with
creatine.10 Occasional case reports report more serious
adverse affects, in particular involving renal and hepatic function, but evidence to support these have not been
found in studies.11 However, those with renal disease or
at risk of renal dysfunction are usually recommended to
avoid creatine supplementation or monitor renal function
carefully if creatine is taken.1
to exercise may enhance these effects. Adequate hydration is important to avoid cramping problems. In addition, preliminary results suggest that creatine may have
other beneficial effects during aging, particularly a slowing of cognitive decline.2 However, the equivocal nature
of the results to date suggest either that only some people
benefit from creatine supplementation, or that more needs
to be understood about how creatine is administered. It
appears that taking creatine immediately before or after
exercise may be more important than how much is taken. While creatine supplements are safe, similar benefits
may be obtained from dietary creatine, such as by eating
a meal with red meat or seafood immediately before or
after exercise. n
Drug Interactions
No drug interactions are known, although concerns
about the potential for renal toxicity raise issues about
drugs metabolized through the kidneys.
References
1. Maughan RJ, et al. Dietary supplements for athletes:
Emerging trends and recurring themes. J Sports Sci
2011;29(Suppl 1):S57-S66.
Formulation
Creatine is readily available from meat and fish (containing roughly 4-5 g/kg), and therefore, is classified as
a dietary supplement, not a drug. As a supplement, it is
most commonly available as a monohydrate in powder,
candy, gum, and liquid. Many synthetic derivatives are
available, including creatine malate, creatine pyruvate,
creatine citrate, creatine-magnesium chelate, creatine
ethyl ester, and many more. Claims that any one of these
is more effective than another have not been supported
in the few independent assessments available.1 Numerous
products combine creatine with vitamins, nutrients, and
other supplements, but clinical studies of these were not
identified. Athletes usually “load” with 20-25 g creatine
per day for 5-7 days (usually 5 g qid), followed by one 2 g
daily dose. Studies with older people have used this regimen, or they were given 2-5 g per day.
2. Rawson ES, Venezia AC. Use of creatine in the elderly
and evidence for effects on cognitive function in young
and old. Amino Acids 2011;40:1349-1362.
3. Candow DG. Sarcopenia: current theories and the potential beneficial effect of creatine application strategies.
Biogerontolog 2011;12:273-281.
4. Dalbo VJ, et al. The effects of age on skeletal muscle
and the phosphocreatine energy system: Can creatine
supplementation help older adults. Dyn Med 2009;8:6.
5. Greenhaff PL, et al. Influence of oral creatine supplementation of muscle torque during repeated bouts
of maximal voluntary exercise in man. Clin Sci
1993;84:565-571.
6. Bermon SP, et al. Effects of creatine monohydrate ingestion in sedentary and weight-trained older adults. Acta
Physiol Scand 1998;164:147-155.
7. Eijnde BO, et al. Effects of creatine supplementation
and exercise training on fitness in men 55-75 yr old. J Appl Physiol 2003;95:818-828.
Conclusion
Numerous studies of creatine supplementation by
athletes have demonstrated beneficial effects on muscle
mass and strength after high-intensity exercise. Such research with older adults is less extensive. Most, but not
all, studies support a beneficial effect on muscle mass and
strength either with or without resistance exercise. It remains unclear whether muscle creatine storage decreases
with age, or whether this is a function of reduced activity
and dietary creatine intake. If it is the latter, this may explain some of the variability obtained in the studies conducted to date.
8. Candow DG, Chilibeck PD. Timing of creatine or protein
supplementation and resistance training in the elderly.
Appl Physiol Nutr Metab 2008;33:184-190.
9. Branch JD. Effect of creatine supplementation on body
composition and performance: A meta-analysis. Int J
Sport Nutr Exerc Metabol 2003;13:198-226.
10. Chrusch MJ, et al. Creatine supplementation combined
with resistance training in older men. Med Sci Sports
Exerc 2001;33:2111-2117.
11. Persky AM, Rawson ES. Safety of creatine supplementation. Subcell Biochem 2007;46:275-289.
Recommendation
Resistance training is beneficial in preventing or reversing the loss of muscle mass and strength that occurs
with aging. Creatine supplementation alone or in addition
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