Source: Medical news Today
Date:   August 24, 2004
URL:    http://www.medicalnewstoday.com/medicalnews.php?newsid=12430


Study links nutritional supplement, creatine, to increased metabolic energy
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A Temple University researcher seeking physiological evidence of chronic
fatigue syndrome (CFS) has found a link between creatine and metabolic
energy. The findings, which hold promise for future CFS treatments, were
published in a recent issue of the Journal of Applied Physiology.

"We found that creatine affects mitochondria - the parts of the cells
that produce energy for all biological functioning - in normal human
subjects. Now that we have established this baseline evidence, we are
looking at the link between creatine and energy production in CFS
patients," said lead author Sinclair Smith, Sc.D., assistant professor of
occupational therapy in Temple's College of Health Professions.

Creatine, thought to build muscle and improve performance, is a popular
over-the-counter supplement used by athletes. Smith and his colleagues
wondered if creatine could also be used to help relieve the extreme
physical and mental fatigue that strikes CFS sufferers.

"Many physicians still don't believe that CFS exists, making it important
to investigate possible physiologic differences and to determine if we can
impact metabolic function in CFS patients," explained Smith. "In addition
to improving muscle metabolic function, recent studies show that creatine
supplementation may improve nervous system function as well.  Given that
cognitive fatigue is a frequent symptom of CFS, we thought that creatine
may enhance both muscle and neural metabolic status in people with CFS,"
said Smith.

In the study, "Use of phosphocreatine kinetics to determine the influence
of creatine on muscle mitochondrial respiration: an in vivo 31P-MRS study
of oral creatine ingestion," the researchers analyzed the effect of
naturally produced and supplemental creatine on the rate of muscle
metabolism using non-invasive magnetic resonance imaging (MRI) techniques
during exercise and rest.

While previous studies have evaluated the link between creatine and
mitochondria in animals and human muscle samples, Smith's was the first
lab to test in people.

Smith collaborated in this research with the U.S. Army Research Institute
of Environmental Medicine, Brigham and Women's Hospital and Harvard
Medical School, Boston University and Sargent College of Health and
Rehabilitation Sciences.

Contact: Eryn Jelesiewicz
dobeck@temple.edu
215-707-0730
Temple University

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(c) 2004 Medical news Today

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Source: Journal of Applied Physiology
        vol 96, #6, pages 2288-2292
Date:   June 2004
URL:    http://jap.physiology.org/contents-by-date.0.shtml


Use of phosphocreatine kinetics to determine the influence of creatine on
muscle mitochondrial respiration: an in vivo 31P-MRS study of oral
creatine ingestion
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Sinclair A. Smith(1), Scott J. Montain(2), Gary P. Zientara(3), and Roger
A. Fielding(4)
1 Neuromuscular Function Laboratory, Department of Occupational Therapy,
  Temple University, Philadelphia, Pennsylvania 19140;
2 United States Army Research Institute of Environmental Medicine, Natick
  01760;
3 Department of Radiology, Brigham and Women's Hospital and Harvard Medical
  School, Boston 02115; and
4 Boston University, Sargent College of Health and Rehabilitation
  Sciences, Boston, Massachusetts 02215

Submitted 23 September 2003 ; accepted in final form 3 February 2004


Abstract

Recent human isolated muscle fiber studies suggest that phosphocreatine
(PCr) and creatine (Cr) concentrations play a role in the regulation of
mitochondrial respiration rate. To determine whether similar regulatory
mechanisms are present in vivo, this study examined the relationship
between skeletal muscle mitochondrial respiration rate and end-exercise
PCr, Cr, PCr-to-Cr ratio (PCr/Cr), ADP, and pH by using 31P-magnetic
resonance spectroscopy in 16 men and women (36.9 p/m 4.6 yr). The initial
PCr resynthesis rate and time constant (Tc) were used as indicators of
mitochondrial respiration after brief (10-12 s) and exhaustive (1-4
min) dynamic knee extension exercise performed in placebo and
creatine-supplemented conditions. 

The results show that the initial PCr
resynthesis rate has a strong relationship with end-exercise PCr, Cr, and
PCr/Cr (r>0.80, P<0.001), a moderate relationship with end-exercise ADP
(r=0.77, P<0.001), and no relationship with end-exercise pH (r=-0.14,
P=0.34). The PCr Tc was not as strongly related to PCr, Cr, PCr/Cr, and
ADP (r<0.77, P<0.001-0.18) and was significantly influenced by
end-exercise pH (r=-0.43, P<0.01). 

These findings suggest that
end-exercise PCr and Cr should be taken into consideration when PCr
recovery kinetics is used as an indicator of mitochondrial respiration and
that the initial PCr resynthesis rate is a more reliable indicator of
mitochondrial respiration compared with the PCr Tc.

Keywords: skeletal muscle; creatine kinase; mitochondria; phosphocreatine;
phosphorous-31 magnetic resonance spectroscopy

Address for reprint requests and other correspondence: S.A. Smith, Temple
Univ., Neuromuscular Function Laboratory, Dept. of Occupational Therapy,
3307 North Broad St., Philadelphia, PA 19140
(E-mail: sinclair.smith@temple.edu).

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(c) 2004 American Physiological Society.