The evading viruses destroys helper T cells or the CD4+ thus the body can no longer stop some infections. The secondary infections also called opportunistic infections are rampant with people who have AIDS. This is because helper T cells help fight against most infections in the body.
Due to their immense oxygen needs, slow-twitch fibers are associated with many blood vessels, mitochondria, and increased concentrations of myoglobin, an oxygen-binding protein in the blood that provides muscles their reddish coloring.