It is critical for both the aerobic and anaerobic energy production. Malic acid breaks this bottleneck and allows energy production and facilitates enhanced endurance. Only tissue malate was depleted. Continual exercise forced the body to use muscle breakdown to feed malic acid production. This resulted in muscle damage.
Endurance training enhances the production of enzymes used to create malic acid.
Even small amounts of malic acid given to rats greatly enhanced their endurance. Their utilization of oxygen and carbohydrate remained unchanged, meaning it was the malic acid that caused the increase in endurance. It is thought that a localized hypoxia in muscle tissue is a cause of fibromyalgia . This results in muscle breakdown, damage and pain, together with muscle wasting. A study in humans showed that administration of 1200 mg to 2400 mg of Malic acid caused a subjective decrease in muscle pain in subjects given it, and this improvement lasted for 48 hours after discontinuing it.