Unilateral vs. Bilateral Training: Which One Is Better?
This week’s study: Are Unilateral Exercises More Effective Than Bilateral Exercises?
Exercise selection is one of the fundamental features of an effective strength training program.
Bilateral exercises such as the squat and bench press have been predominant in strength training for decades. When we talk about overall strength, we typically refer to bilateral movements, the ones that use both limbs in unison, as opposed to unilateral exercises which work one limb at a time.
However, recent research has shown the importance of incorporating single-limb exercises during training, in order to maximize strength, hypertrophy and power.
One of the main indicators of the significance of unilateral training is the existence of a phenomenon known as bilateral limb deficit (BLD). This deficit refers to the difference between the sum of maximal force output by each limb (for example, the sum of the strength in each leg during a split-squat) and the maximal force output from a bilateral exercise, as in a regular squat.
Why does BLD matter?
Research has shown that in unilateral exercises, each limb can contribute to more than 50% of power output in bilateral exercises. That means, if you can perform a one-arm chest press with 25 lbs but can only bench 40 lbs, you are limiting your strength gains in the bilateral exercise.
Although both bilateral and unilateral training are effective in increasing muscle strength, power and hypertrophy, unilateral training has been show to be more effective at reducing the bilateral limb deficit, which could be translated into better athletic performance.
For example, single-leg vertical jumping is greatly increased through unilateral training when compared to bilateral training, and it has a direct carryover to many sports.
ere are a few more advantages of unilateral training:
– Efficiency in recruiting target mucles while increasing the use of stabilizing muscles (for example, the adductors during a split-squat)
– Increased need for core strength, stability and balance
– Immediate feedback with relation to limb symmetry, which can be used in injury prevention
– Decreased load compared to their bilateral counterparts, which is useful in overloading the target muscle without taxing other areas of the body. (For example, if you’re looking to increase leg hypertrophy or strength without overloading the lower back in the case of an injury, you could opt for the split-squat instead)
The bottom line: While bilateral exercises make up the bulk of most trainee’s program, unilateral exercises must be implemented according to the overall training goal and at the appropriate times during a training cycle in order to even out imbalances and enhance single-limb force production.
Until next time,
Mullican, K., & Nijem, R. (2016). Are Unilateral Exercises More Effective Than Bilateral Exercises? Strength and Conditioning Journal, 38(1), 68-70.