2. Latissimus Dorsi
Latissimus Dorsi has a pet name, of course: lat. Lat is one of the widest muscles in your body, and it’s at your back, spreading down your spine. Pull-ups, chin-ups, lat pulldowns, and swimming are groups of exercises that make it even more active. It responds best to a medium number of repetitions because it has a mixture of fast and slow twitch muscles.