Single joint exercises are fine for certain people who are looking for specific results, like body builders who need to show off each muscle individually, but for the average gym user these exercises are not suitable. They can also cause aches and pains because you end up imbalanced by focusing on one muscle while neglecting another. Muscles work together like a chain. If you only focus on one muscle at a time you are making the other muscles in the chain weaker.

Multi-joint exercises are more true to our everyday movements. Therefore, if you focus on these types of exercises during your workouts you improve the functional movement of your body. You’re also able to cut your gym time in half and still get all the workout and you will no longer have to split your workouts into muscle groups. By using more muscle groups per exercise you’ll increase your metabolism which helps to burn more fat.

Squats and deadlifts are the two best multi-joint exercises because they are great for improving overall strength and work almost every muscle in the body. Along with squats and deadlifts you should incorporate other multi-joint rotational exercises to keep your body strong and increase your range of motion improving your ability to function better when partaking in daily activities.

The following are examples of different categories of multi-joint exercises.

Linear Motion Exercises
These are exercises where the path of motion follows along a straight or linear line. A chest press performed on a Smith Machine is an example of an exercise with a linear motion.

Rotational Motion Exercises
Are exercises where the path of motion is a circular rotation around a fixed axis. Many resistance training machines provide this type of motion.

Curvilinear Motion Exercises
Exercises that include an arching motion due to the joint's natural rotation are called curvilinear motion exercises. A barbell shoulder press could be an example of an exercise with a curvilinear motion if performed with this goal.

Singular-Plane Joint Motion Exercises
Are exercises that completely transpire in a single, perpendicular plane of motion. They can be any of the above types of motions or even combinations of them as long as the total motion remains in only one plane.

Multiple-Plane Joint Motion Exercises
Combine two or more motions in such a manner that the motion moves through more than one plane. An example of this motion would be performing a dumbbell front deltoid press while rotating the arms and dumbbells as they are elevated.