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Creatine Supplementation
Creatine is a naturally occurring amino acid that is obtained from the diet
and/or synthesized endogenously (within the body) from the amino acids glycine,
arginine and methionine. Creatine has become a popular nutritional supplement
among athletes. The most commonly used protocol is to ingest a daily total of 20 to
30 grams of creatine, usually creatine monohydrate, in four equal doses of five to
seven grams dissolved in fluids over the course of day. (For a detailed review on
creatine supplementation strategies, see my article Creatine Loading Strategies in
November issue of MD).
Although not all studies report significant results, the preponderance of
scientific evidence indicates that creatine supplementation appears to be a generally
effective nutritional ergogenic aid for a variety of exercise tasks in a number of
athletic and clinical populations.1
For example, short-term creatine supplementation has been reported to
improve maximal power/strength (5-15%), work performed during sets of maximal
effort muscle contractions (5-15%), single-effort sprint performance (1-5%) and work
performed during repetitive sprint performance (5-15%).1 Moreover, creatine
supplementation during training has been reported to promote significantly greater
gains in strength, fat-free mass and performance, primarily of high- intensity
performance tasks.1
In the 1970s, Soviet scientists showed that creatine supplementation
improved athletic performance in short, intense activities such as sprints.2 According
to Dr. Michael Kalinski, a former Chairman of the Exercise Biochemistry Department
in the Kiev State Institute of Physical Education (Kiev, Ukraine, USSR), the Central
Institute of Physical Culture (CIPC) in Moscow initiated a long-term research
program to characterize the role of creatine in muscular performance and its use to
enhance muscle function. Also, Soviet scientists redirected their research from
academic studies on creatine metabolism in animals to applied studies on the
effects of creatine supplementation on human physical performance.2
For example, members of the USSR national track and field team who took
creatine supplements improved their performance in the 100-meter dash by one
percent and in the 200-meter sprint by 1.7 percent.2 As a result of these studies,
the CIPC officially recommended use of creatine supplements to enhance physical
capacity and the efficacy of exercise training. In additon, USSR national athletes
were routinely given these supplements.2
Some clinicians have expressed concern about the effects of creatine on
renal function. Drs. Pritchard and Kaira reported a case study of renal dysfunction
associated with creatine,3 but their conclusion that creatine was responsible for the
renal dysfunction is clouded by previous history of renal nephritic syndroma that was
stabilized by cyclosporine. It was unclear whether the observed improvement in
renal function following creatine withdrawal was due to adverse effects of creatine
itself, impurities in the creatine products, creatine/drug interactions and/or other
factors.
In three small studies, no adverse effects of creatine on renal function were
reported following either short-term4,5 or long-term supplementation of two to 30
grams per day for up to five years.6 Moreover, Dr. Richard Kreider and co-workers
recently reported that long-term creatine supplementation (up to 21 months) does
not appear to adversely affect markers of health status (metabolic markers, muscle
and liver enzymes, electrolytes, lipid profiles, etc.) in athletes undergoing intense
training in comparison to athletes who do not take creatine.7 There have also been
anecdotal reports of muscle cramping and strains associated with creatine
supplementation. However, Dr. Greenwood and colleagues recently reported that
creatine supplementation does not appear to increase the incidence of injury or
cramping in Division IA college football players.8
Phosphate Supplementation
Among the inorganic elements, phosphorous is second only to calcium in
abundance in the human body. Approximately 85 percent of the body´s
phosphorous is in the skeleton, one percent is found in the blood and body fluids,
and the remaining 14 percent is associated with soft tissue such as muscle.9
Phosphorous is of vital importance in intermediary metabolism of the energy
nutrients, contributing to the metabolic potential in the form of high-energy
phosphate bonds, such as ATP, and through phosphorylation of substrates.
Phosphate also functions in acid-base balance. Within cells, phosphate is the main
intracellular buffer.
Further, phosphate is involved in oxygen delivery. In red blood cells,
synthesis of 2,3-diphosphoglycerate requires phosphorus. Decreased 2,3-
diphosphoglycerate diminishes release of oxygen to tissues. Phosphorous is widely
distributed in foods. The best food sources are meat, poultry, fish, eggs and milk
products. Nuts, legumes, cereals, grains and chocolate also contain phosphorous;
however, animal products are superior sources of available phosphorus compared
with cereals and soy-based foods. Many phosphate-containing supplements are
available commercially, including K-Phos® and Neutra-Phos K®, which also provide
potassium. For maximum bioavailability, these supplements should not be ingested
with zinc, iron, or magnesium.9 Calcium (as calcium acetate or calcium carbonate)
also inhibits phosphorous absorbtion.9
Phosphate supplementation (“phosphate loading”) has been proposed as an
aid to athletic performance (Table 1).10 Studies investigating the ergogenic value of
phosphate supplementation date back to the 1920s. Early studies suggested that
phosphate salt supplementation could be used to increase physical working
capacity.10
Much of the contemporary interest in phosphate supplementation as a
potential ergogenic aid emanated from a report by Dr. Cade and colleagues in the
early 1980s.11 Results revealed that phosphate supplementation significantly
increased resting serum phosphate and red cell 2,3-diphosphoglyserate levels. In
addition, phosphate supplementation decreased submaximal lactate while
increasing maximal oxygen uptake. The greatest increase in maximal oxygen
uptake occurred in subjects ingesting sodium phosphate for two consecutive testing
trials.
Dr. Richard Kreider and co-workers conducted the most extensive study to
date to evaluate the ergogenic value of phosphate supplementation.12 In this study,
six highly trained male cyclists participated in a placebo-controlled, double blind
crossover study to determine the effects of sodium phosphate supplementation on
metabolic and myocardial adaptations to maximal exercise and 40-km time trial
performance. Subjects ingested either four grams per day of tribasic sodium
phosphate or a glucose placebo for five days. On the fourth day, subjects performed
either an incremental maximal cycling test or a 40-km stimulated time trial under
controlled laboratory conditions using the subjects’ racing bicycle attached to a
computerized race stimulator.
Analysis of maximal test results revealed that phosphate supplementation
significantly increased pre-max serum phosphate levels (17%), maximal oxygen
uptake (9%), minute ventilation (8%), ventilatory anaerobic threshold (10%),
echocardiographically-determined mean ejection fraction (4%) and myocardial
fractional shortening (8%). During the 40-km time trial, phosphate loading
significantly increased mean power output (17%), oxygen uptake (18%), ventilation
(15%), heart rate (8%), ejection fraction (13%) and fractional shortening resulting in
an eight percent reduction in performance time. These findings provide evidence
that sodium phosphate supplementation provides ergogenic value to highly trained
athletes.
According to recent review with Dr. Kreider, “Most studies investigating the
effects of sodium phosphate supplementation (three or four grams per day for three
or four days) on maximal aerobic capacity and/or endurance exercise performance
have reported ergogenic benefit… On the other hand, it appears that acute and/or
chronic calcium phosphate supplementation provides little ergogenic value.”10
Table 1. Proposed Theoretical Ergogenic Value of Phosphate
Supplementation
• Elevates extracellular and intracellular phosphate concentration
• Stimulates glycolysis and energy metabolism
• Increase the availability of phosphate for oxidative phosphorylation
and creatine phosphate synthesis
• Increases 2,3-diphosphoglycerate synthesis and peripheral extraction
of oxygen.
• Enhances myocardial and cardiovascular responses to exercise
• Serves as a metabolic buffer
• Increases anaerobic threshold and maximal oxygen uptake
• Improves exercise performance and/or efficiency
• May enhance psychological responses to exercise
Data from Kreider, 1999
Creatine Phosphate Supplementation
In their recent book Supplements for Strength-Power Athletes13, Drs. Jose
Antonio and Jeffrey Stout quoted results by Dr. Wallace and colleagues published in
Coaching and Sports Science Journal and unpublished results by Dr. Eckerson. Dr.
Wallace and co-workers investigated the effect of supplemental creatine alone
versus creatine plus phosphate on muscle power. Male and female subjects were
given either five grams of creatine four times per day or five grams of creatine plus
one gram of phosphate four times per day for five days. The combination of creatine
plus phosphate resulted in a significantly higher muscle power output, suggesting
performance benefits more from a combination of phosphates and creatine than
from creatine alone.
Dr. Eckerson and colleagues examined the effects of creatine alone versus
creatine plus phosphate on anaerobic working capacity. Male subjects were
randomly put into one of three treatments: placebo, five grams of creatine, or five
grams of creatine plus one gram of phosphates. Each subject was asked to dissolve
the supplement in 16 ounces of water and ingest it four times per day for six
consecutive days. The subjects performed a cycle ergometry test to determine
anaerobic working capacity. The placebo and creatine groups increased anaerobic
working capacity by –3.0 percent and 16.0 percent, respectively. The creatine plus
phosphate group increased anaerobic working capacity by 49 percent.
Phosphate and Resting Metabolic Rate
Phosphate supplementation has also been suggested to affect energy
expenditure. For example, Dr. Kaciuba-Uscilko and colleagues reported that
phosphate supplementation during a four-week weight loss program increased
resting metabolic rate.14 Further, Dr. Nazar and co-workers reported that phosphate
supplementation during an eight-week weight loss program increased resting
metabolic rate by 12-19 percent and prevented a normal decline in thyroid
hormones.15 Consequently, it’s possible that phosphate could serve as a potential
thermogenic nutrient in diet supplements.
Summing Up
The preponderance of scientific evidence indicates that creatine
supplementation appears to be a generally effective nutritional ergogenic aid for a
variety of exercise tasks in a number of athletic and clinical populations. There is
some evidence suggesting that sodium phosphate supplementation may enhance
aerobic capacity. Recent data suggest that combined creatine and phosphate
ingestion improves anaerobic working capacity more than creatine ingestion alone.
According to Drs. Jose Antonio and Jeffrey Stout, take a one-gram serving
phosphates (preferably a sodium-potassium mix) with every serving of creatine
during the loading phase, which would be four times daily for six days.
Creatine is a naturally occurring amino acid that is obtained from the diet
and/or synthesized endogenously (within the body) from the amino acids glycine,
arginine and methionine. Creatine has become a popular nutritional supplement
among athletes. The most commonly used protocol is to ingest a daily total of 20 to
30 grams of creatine, usually creatine monohydrate, in four equal doses of five to
seven grams dissolved in fluids over the course of day. (For a detailed review on
creatine supplementation strategies, see my article Creatine Loading Strategies in
November issue of MD).
Although not all studies report significant results, the preponderance of
scientific evidence indicates that creatine supplementation appears to be a generally
effective nutritional ergogenic aid for a variety of exercise tasks in a number of
athletic and clinical populations.1
For example, short-term creatine supplementation has been reported to
improve maximal power/strength (5-15%), work performed during sets of maximal
effort muscle contractions (5-15%), single-effort sprint performance (1-5%) and work
performed during repetitive sprint performance (5-15%).1 Moreover, creatine
supplementation during training has been reported to promote significantly greater
gains in strength, fat-free mass and performance, primarily of high- intensity
performance tasks.1
In the 1970s, Soviet scientists showed that creatine supplementation
improved athletic performance in short, intense activities such as sprints.2 According
to Dr. Michael Kalinski, a former Chairman of the Exercise Biochemistry Department
in the Kiev State Institute of Physical Education (Kiev, Ukraine, USSR), the Central
Institute of Physical Culture (CIPC) in Moscow initiated a long-term research
program to characterize the role of creatine in muscular performance and its use to
enhance muscle function. Also, Soviet scientists redirected their research from
academic studies on creatine metabolism in animals to applied studies on the
effects of creatine supplementation on human physical performance.2
For example, members of the USSR national track and field team who took
creatine supplements improved their performance in the 100-meter dash by one
percent and in the 200-meter sprint by 1.7 percent.2 As a result of these studies,
the CIPC officially recommended use of creatine supplements to enhance physical
capacity and the efficacy of exercise training. In additon, USSR national athletes
were routinely given these supplements.2
Some clinicians have expressed concern about the effects of creatine on
renal function. Drs. Pritchard and Kaira reported a case study of renal dysfunction
associated with creatine,3 but their conclusion that creatine was responsible for the
renal dysfunction is clouded by previous history of renal nephritic syndroma that was
stabilized by cyclosporine. It was unclear whether the observed improvement in
renal function following creatine withdrawal was due to adverse effects of creatine
itself, impurities in the creatine products, creatine/drug interactions and/or other
factors.
In three small studies, no adverse effects of creatine on renal function were
reported following either short-term4,5 or long-term supplementation of two to 30
grams per day for up to five years.6 Moreover, Dr. Richard Kreider and co-workers
recently reported that long-term creatine supplementation (up to 21 months) does
not appear to adversely affect markers of health status (metabolic markers, muscle
and liver enzymes, electrolytes, lipid profiles, etc.) in athletes undergoing intense
training in comparison to athletes who do not take creatine.7 There have also been
anecdotal reports of muscle cramping and strains associated with creatine
supplementation. However, Dr. Greenwood and colleagues recently reported that
creatine supplementation does not appear to increase the incidence of injury or
cramping in Division IA college football players.8
Phosphate Supplementation
Among the inorganic elements, phosphorous is second only to calcium in
abundance in the human body. Approximately 85 percent of the body´s
phosphorous is in the skeleton, one percent is found in the blood and body fluids,
and the remaining 14 percent is associated with soft tissue such as muscle.9
Phosphorous is of vital importance in intermediary metabolism of the energy
nutrients, contributing to the metabolic potential in the form of high-energy
phosphate bonds, such as ATP, and through phosphorylation of substrates.
Phosphate also functions in acid-base balance. Within cells, phosphate is the main
intracellular buffer.
Further, phosphate is involved in oxygen delivery. In red blood cells,
synthesis of 2,3-diphosphoglycerate requires phosphorus. Decreased 2,3-
diphosphoglycerate diminishes release of oxygen to tissues. Phosphorous is widely
distributed in foods. The best food sources are meat, poultry, fish, eggs and milk
products. Nuts, legumes, cereals, grains and chocolate also contain phosphorous;
however, animal products are superior sources of available phosphorus compared
with cereals and soy-based foods. Many phosphate-containing supplements are
available commercially, including K-Phos® and Neutra-Phos K®, which also provide
potassium. For maximum bioavailability, these supplements should not be ingested
with zinc, iron, or magnesium.9 Calcium (as calcium acetate or calcium carbonate)
also inhibits phosphorous absorbtion.9
Phosphate supplementation (“phosphate loading”) has been proposed as an
aid to athletic performance (Table 1).10 Studies investigating the ergogenic value of
phosphate supplementation date back to the 1920s. Early studies suggested that
phosphate salt supplementation could be used to increase physical working
capacity.10
Much of the contemporary interest in phosphate supplementation as a
potential ergogenic aid emanated from a report by Dr. Cade and colleagues in the
early 1980s.11 Results revealed that phosphate supplementation significantly
increased resting serum phosphate and red cell 2,3-diphosphoglyserate levels. In
addition, phosphate supplementation decreased submaximal lactate while
increasing maximal oxygen uptake. The greatest increase in maximal oxygen
uptake occurred in subjects ingesting sodium phosphate for two consecutive testing
trials.
Dr. Richard Kreider and co-workers conducted the most extensive study to
date to evaluate the ergogenic value of phosphate supplementation.12 In this study,
six highly trained male cyclists participated in a placebo-controlled, double blind
crossover study to determine the effects of sodium phosphate supplementation on
metabolic and myocardial adaptations to maximal exercise and 40-km time trial
performance. Subjects ingested either four grams per day of tribasic sodium
phosphate or a glucose placebo for five days. On the fourth day, subjects performed
either an incremental maximal cycling test or a 40-km stimulated time trial under
controlled laboratory conditions using the subjects’ racing bicycle attached to a
computerized race stimulator.
Analysis of maximal test results revealed that phosphate supplementation
significantly increased pre-max serum phosphate levels (17%), maximal oxygen
uptake (9%), minute ventilation (8%), ventilatory anaerobic threshold (10%),
echocardiographically-determined mean ejection fraction (4%) and myocardial
fractional shortening (8%). During the 40-km time trial, phosphate loading
significantly increased mean power output (17%), oxygen uptake (18%), ventilation
(15%), heart rate (8%), ejection fraction (13%) and fractional shortening resulting in
an eight percent reduction in performance time. These findings provide evidence
that sodium phosphate supplementation provides ergogenic value to highly trained
athletes.
According to recent review with Dr. Kreider, “Most studies investigating the
effects of sodium phosphate supplementation (three or four grams per day for three
or four days) on maximal aerobic capacity and/or endurance exercise performance
have reported ergogenic benefit… On the other hand, it appears that acute and/or
chronic calcium phosphate supplementation provides little ergogenic value.”10
Table 1. Proposed Theoretical Ergogenic Value of Phosphate
Supplementation
• Elevates extracellular and intracellular phosphate concentration
• Stimulates glycolysis and energy metabolism
• Increase the availability of phosphate for oxidative phosphorylation
and creatine phosphate synthesis
• Increases 2,3-diphosphoglycerate synthesis and peripheral extraction
of oxygen.
• Enhances myocardial and cardiovascular responses to exercise
• Serves as a metabolic buffer
• Increases anaerobic threshold and maximal oxygen uptake
• Improves exercise performance and/or efficiency
• May enhance psychological responses to exercise
Data from Kreider, 1999
Creatine Phosphate Supplementation
In their recent book Supplements for Strength-Power Athletes13, Drs. Jose
Antonio and Jeffrey Stout quoted results by Dr. Wallace and colleagues published in
Coaching and Sports Science Journal and unpublished results by Dr. Eckerson. Dr.
Wallace and co-workers investigated the effect of supplemental creatine alone
versus creatine plus phosphate on muscle power. Male and female subjects were
given either five grams of creatine four times per day or five grams of creatine plus
one gram of phosphate four times per day for five days. The combination of creatine
plus phosphate resulted in a significantly higher muscle power output, suggesting
performance benefits more from a combination of phosphates and creatine than
from creatine alone.
Dr. Eckerson and colleagues examined the effects of creatine alone versus
creatine plus phosphate on anaerobic working capacity. Male subjects were
randomly put into one of three treatments: placebo, five grams of creatine, or five
grams of creatine plus one gram of phosphates. Each subject was asked to dissolve
the supplement in 16 ounces of water and ingest it four times per day for six
consecutive days. The subjects performed a cycle ergometry test to determine
anaerobic working capacity. The placebo and creatine groups increased anaerobic
working capacity by –3.0 percent and 16.0 percent, respectively. The creatine plus
phosphate group increased anaerobic working capacity by 49 percent.
Phosphate and Resting Metabolic Rate
Phosphate supplementation has also been suggested to affect energy
expenditure. For example, Dr. Kaciuba-Uscilko and colleagues reported that
phosphate supplementation during a four-week weight loss program increased
resting metabolic rate.14 Further, Dr. Nazar and co-workers reported that phosphate
supplementation during an eight-week weight loss program increased resting
metabolic rate by 12-19 percent and prevented a normal decline in thyroid
hormones.15 Consequently, it’s possible that phosphate could serve as a potential
thermogenic nutrient in diet supplements.
Summing Up
The preponderance of scientific evidence indicates that creatine
supplementation appears to be a generally effective nutritional ergogenic aid for a
variety of exercise tasks in a number of athletic and clinical populations. There is
some evidence suggesting that sodium phosphate supplementation may enhance
aerobic capacity. Recent data suggest that combined creatine and phosphate
ingestion improves anaerobic working capacity more than creatine ingestion alone.
According to Drs. Jose Antonio and Jeffrey Stout, take a one-gram serving
phosphates (preferably a sodium-potassium mix) with every serving of creatine
during the loading phase, which would be four times daily for six days.
