Almost every major muscle in your body has a twin—left pec, right pec; left quad, right quad; left triceps, right triceps, and so on.

Thus, one type of muscle imbalance is a size or strength discrepancy between a pair of such muscles. Bodybuilders refer to this as “asymmetry.”

Another type of muscle imbalance can exist between pairs of major muscle groups, like your chest and back, triceps and biceps, and upper legs and calves.

If any of the muscles in these opposing pairs are smaller or weaker and less developed than the other, visual symmetry and performance suffer, and sometimes, the risk of injury rises.12 Bodybuilders call this “disproportion.”

So, the ultimate physique goal is twofold:

  1. Symmetrical-looking muscles on each side of your body
  2. Proportionate development of the upper and lower and front and back parts of your body

Fortunately, 80 percent of this is following a well-designed strength training program that’s built on compound exercises that train your entire body evenly.

That usually isn’t enough to fully prevent and fix muscle imbalances, though. To do that, you should also:

  1. Regularly do unilateral exercises, which are movements that train one limb at a time, like the dumbbell lunge, alternating dumbbell curl, and Bulgarian split squat.

    These types of exercises negate the physiological biases that can creep into bilateral exercises, which train both limbs simultaneously (like the barbell squat, barbell bench press, and barbell deadlift).

    With unilateral exercises, you can’t unwittingly favor one side of your body—each limb must “pull its own weight.”

  2. Start your sets of unilateral exercises with your weaker side and end your sets when your weaker side fails.

    By doing this, you keep from racking up more volume on your stronger side.

  3. Train the weaker and smaller muscle pairs and muscle groups more than the bigger and stronger ones.

    For example, if your left shoulder is smaller than your right, and you do about 30 reps of dumbbell side lateral raises per week per side, you could bump your left-side raises up to 40 reps per week.

    Similarly, if your legs are too small compared to your upper body despite years of proper strength training, and if you’re doing, say, 12 hard sets (working sets) per week for your legs, you could increase this to 15 hard sets per week.

Scientific References +