Updated: Sep 5, 2020
In bilateral deficit, maximal contraction of both limbs is lower than the sum of the forces produced by the left and right limbs separately. It seems that, this phenomenon is due to brain divided attention that contribute on inhibitory brain input.
For different sports that require to be practiced (training) in specific methods, unilateral training can be useful in attenuation of inhibitory brain input, and as a result, in both unilateral and bilateral contractions, the strength increases and force deficit during contractions decreased.
Another advantage of unilateral training is gaining muscle symmetry. If your arms, legs or one side of your body are small/weak muscle groups, consider bilateral exercises to correct the asymmetry. In this regard, "My favorite method for improving weak and small muscles is to use unilateral training" says Jesse Hobbes. My left quad muscle is always being my weakness, so I focus on performing single-leg press, Single-leg squats, or leg extension machine exercise in order to achieve muscle balance. If you have always performed your workouts through bilateral exercise, barbells or machine, now try to add unilateral training to your program to develop your muscles balance. In addition, constantly strength training with bilateral and standard exercises leads to stronger part of the muscle will always be more involved in the exercise bout, and the weaker part will always be behind. Therefore, one part your body stay smaller and weaker. unilateral training will help you to avoid this condition.