Aspartic acid is converted intracellularly into oxaloacetate, an important substrate in the energy- producing Krebs cycle, and is also a carrier molecule for the transport of potassium and magnesium into the cell. In the potassium and magnesium aspartate studies of the '60s, a beneficial effect was usually noted after 4-5 days, but sometimes 10 days were required. Patients usually continued treatment for 4-6 weeks. In most cases, fatigue did not return after treatment was discontinued. Since very small quantities of ATP are stored within the muscle cell, it must be constantly replenished.
Creatine phosphate has that ability.
Creatine is a small molecular weight compound similar in size to an amino acid, found especially in the muscle tissues of vertebrates. The role of creatine phosphate in energy production is simple. When muscle stores of creatine phosphate are inadequate, ATP is regenerated more slowly and muscles are more easily fatigued. A combination of magnesium and malic acid has also been recommended for treatment of chronic fatigue and fibromyalgia. Fibromyalgia pain may respond in as little as 48 hours, while fatigue would generally take approximately two weeks.