A bilateral exercise shares the resistance between two limbs, whereas a unilateral exercise places stress on only one limb. Bilateral exercises have advantages and drawbacks compared to unilateral exercises. A bilateral exercise is better for increasing overall muscle strength, but it might also cause unequal muscle weaknesses.
Bilateral exercises work both sides of your body, as both limbs share the stress of the exercise. A barbell biceps curl is a bilateral exercise; a dumbbell biceps curl is a unilateral exercise. A bilateral exercise can be a multi-joint or single-joint movement. The barbell biceps curl previously mentioned is a single-joint bilateral exercise. The squat is a multi-joint bilateral exercise. You can work several muscles together or target a single muscle group with a bilateral exercise.
According to a study published in the "Journal of Strength and Conditioning Research," long jumpers experienced asymmetrical hip- and ankle-joint torque when performing squats. This is one possible drawback of a bilateral movement. If you perform a biceps curl and your left arm is stronger than your right arm, the left biceps will likely carry more of the load to compensate for the weaker right biceps. Bilateral exercises mask these asymmetries, which you can somewhat correct with unilateral exercises.
Another study published in the Scandinavian journal "Acta Physiologica" noted that subjects who performed bilateral leg extensions experienced a larger average strength gain than subjects who did unilateral leg extensions. However, the strength gain in each individual leg was greater for those who performed unilateral leg extensions. Bilateral exercises increase overall muscle strength. However, unilateral exercises are better for increasing strength in a single muscle. If you want to increase your squat strength, do bilateral squats. If you want to increase the strength in your left leg, do unilateral squats.
If you want to lift heavier weights and increase your overall strength levels, incorporate bilateral exercises into your workout routine. Keep in mind, however, that bilateral exercises limit your movement patterns. For example, if you perform a clean and press with a barbell, you have to pull the barbell using the front of your body. If you use dumbbells, you can pull from the front or the side of your body, allowing you to choose the most comfortable option. Include both bilateral and unilateral exercises in your workout program to reap the benefits from both types of exercises.