9-Muscle soreness and muscle cramps
Anemia has various signs and symptoms associated with physical activity and muscle function, including muscle cramps. When anemia is severe, and there is a significant reduction in the transport of oxygen, the muscle becomes unable to use energy the same way and might start to use an alternate metabolic way that does not require oxygen but leads to the formation of lactic acid. This substance starts accumulating and causes the known muscle soreness associated with exercise.