As the body’s largest muscle, they are responsible for keeping you upright, as well as bending down and taking the stairs. The biggest muscles in the body are the glutes, so for longevity gains, the bottom is a prime target. But did I really have to spend hours in the gym doing squats to achieve stronger glutes? FMS bypasses the body’s normal voluntary activation process by triggering powerful muscle contractions from outside the body. The 36,000 electrically-stimulated muscle contractions in one session only work on the muscles while you’re actually exercising.