Classes that focus on strength and conditioning will often be weight based, with different exercises targeting different groups of muscles. (thefashionablehousewife.com)
Change your grip so that you can focus on different groups of muscles will ensure that you get in a total body workout. (wepullup.com)
Duchenne de Boulogne found that he could artificially induce recognizable facial expressions by sending electrical currents to different groups of muscles in the face. (newscientist.com)