Taken from about.com
Because it is known that heart cells are dependent on adequate levels of ATP to function properly, and that cardiac creatine levels are depressed in chronic heart failure, researchers have looked at supplemental creatine to improve heart function and overall symptomology in certain forms of heart disease. It is well known that people suffering from chronic heart failure have limited endurance, strength and tire easily, which greatly limits their ability to function in everyday life. Using a double blind, placebo-controlled design, 17 patients aged 43 to 70 years with an ejection fraction <40 were supplemented with 20 grams of creatine daily for 10 days. Before and after creatine supplementation, the researchers looked at:
1) Ejection fraction of the heart (blood present in the ventricle at the end of diastole and expelled during the contraction of the heart) 2) 1-legged knee extensor (which tests strength) 3) Exercise performance on the cycle ergometer (which tests endurance)
Biopsies were also taken from muscle to determine if there was an increase in energy-producing compounds (i.e., creatine and creatine phosphate). Interestingly, but not surprisingly, the ejection fraction at rest and during the exercise phase did not increase. However, the biopsies revealed a considerable increase in tissue levels of creatine and creatine phosphate in the patients getting the supplemental creatine. More importantly, patients getting the creatine had increases in strength and peak torque (21%, P < 0.05) and endurance (10%, P < 0.05). Both peak torque and 1-legged performance increased linearly with increased skeletal muscle phosphocreatine (P < 0.05). After just one week of creatine supplementation, the researchers concluded: "Supplementation to patients with chronic heart failure did not increase ejection fraction but increased skeletal muscle energy-rich phosphagens and performance as regards both strength and endurance. This new therapeutic approach merits further attention."10
Another study looked at the effects of creatine supplementation on endurance and muscle metabolism in people with congestive heart failure.11 In particular the researchers looked at levels of ammonia and lactate, two important indicators of muscle performance under stress. Lactate and ammonia levels rise as intensity increases during exercise and higher levels are associated with fatigue. High-level athletes have lower levels of lactate and ammonia during a given exercise than non-athletes, as the athletes' metabolism is better at dealing with these metabolites of exertion, allowing them to perform better. This study found that patients with congestive heart failure given 20 grams of creatine per day had greater strength and endurance (measured as handgrip exercise at 25%, 50% and 75% of maximum voluntary contraction or until exhaustion) and had lower levels of lactate and ammonia than the placebo group. This shows that creatine supplementation in chronic heart failure augments skeletal muscle endurance and attenuates the abnormal skeletal muscle metabolic response to exercise.
