The phrase "to work the muscles" means to exercise the muscles by doing physical activities or movements that make them stronger and more toned. Full definition
Short bridges do an excellent job at working muscles in the back as well as the glutes and hamstrings. (homefitnessguru.net)
When our glutes don't fire, we miss out on working this muscle group in our body and burning a ton of calories and fat when that is our goal. (fitnsync.com)
If you have ever exercised at a gym, you know the importance of working all your muscles for overall fitness and cardiovascular health. (realtormag.realtor.org)