Magnesium is a key catalyst in the cycling of ADP to ATP, and the subsequent hydrolysis of ATP to cleave the high energy phosphate bond of ATP, providing the energy needed for muscle contraction. As depicted in Table II, magnesium is a key component for all of these energy producing systems. Sport performance and exercise require a high supply of the energy produced by magnesium sparked reactions.
Exercise and Magnesium Metabolism
The relationship between magnesium and muscle function, oxygen uptake, energy metabolism, and electrolyte balance has spurred researchers on in the study of exercise and magnesium. Plasma magnesium has been seen to decrease by about 10% following intense exercise, and the resulting low magnesium levels have been seen to last for up to 18 days. Part of this reduction is due to a redistribution of magnesium from the plasma pool to other areas of the body caused by exercise induced metabolic needs, including increased magnesium in exercising muscle, while an increased rate of urinary and sweat loss of magnesium caused by exercise accounts for the majority of the rest. Typically, magnesium loss due to sweat is on the order of 3 to 4 mg/liter, and under normal conditions it accounts for 12% of the total daily magnesium excretion. Urinary magnesium loss can increase by up to 30 percent following a session of strenuous exercise. The increased level of magnesium for exercising muscle may be a larger factor than commonly held. The energy for muscle contraction, of course comes from the cycling of ATP and ADP. Magnesium is a key part of this cycling having more than one role here.
According to Biochemistry; Stryer L, 4th Edition, Fromm & Company 1995:
“ATP turnover is very high as demonstrated by the following examples:”
- An average human consumes 40 kg of ATP in 24 hours when resting
- During exercise 0.5 kg of ATP can be used per minute!
Thus, it is quite obvious that to maintain the body’s normal activities a substantial amount of magnesium is required (see Figure 1).