Lots of people go to the gym to work out. Whether your goal is to build body muscle or lose body fat, some forms of exercise are more effective than others. Primarily, those that help you train multiple joints at once rather than just one.
Heather Milton is a senior exercise physiologist from NYU Langone Health, and she recommends avoiding exercises that focus primarily on one part of your body, as they're less efficient. Such activities include the use of leg-extension equipment or performing exercises like calf raises, bicep curls, and tricep extensions.
Instead, consider exercises that integrate various parts of the body at once; these are called compound movements and will engage multiple parts of your body all at one time. Not only will this use your energy more efficiently, but it will help you exercise more parts of your body and improve your aerobic and cardiovascular health, giving you a better workout overall.
Examples of these kinds of compound movement exercises are chest presses or rows, which involve using muscles all over your body to move the weight. As you do these, you're not only giving your arms a workout, but also muscles throughout the chest region.
Keep in mind that single-muscle workouts are still excellent for maximizing strength in a particular bodily region, but the rest of your body won't benefit too much from them.