Muscles are classified as "fast-twitch" or "slow-twitch." Slow-twitch muscles are found in large or stabilizing muscle groups such as the abdomen or back. These muscle fibers can typically contract for long periods of time and are difficult to fatigue which makes them slow to respond in terms of definition. Fatigue is important because it is a signal of overload that stimulates your muscles to adapt by getting stronger. When a muscle fatigues, the central nervous system initiates mechanisms to increase fiber recruitment within the muscle and eventually cause the muscle…