Lack of time is the most frequent excuse given for not working out. If you do manage to get to the gym you probably won’t be thinking about doing unilateral exercises. Who has the time to perform a one-arm dumbbell shoulder press?

It’s time to make time for working out one side of the body at a time.

If you’ve been doing all bilateral exercises such as squats, lat pull downs, barbell chest press, among other multi-joint and other multi-joint bilateral exercises, chances are that one side of the body is weaker than the other – creating muscle imbalances.

“Machines and symmetrical training exercises pose unnatural environmental stressors. This causes adaptations to a stress that is not consistent with the body’s design. In many cases, as the adaptations become more pronounced they create faulty movement patterns. Certainly the bench and back squat exercise have a place in effective training but without the proper adjuncts these same exercises can actually lead to problems, writes the National Counseling of Strength and Fitness.

Lower versus upper body

Moves that work more than one joint at the same time and both sides of the body simultaneously are the most commonly advised resistance exercises. These types of exercises have proven to maximize the caloric expenditure and the proper hormonal response to get faster results to achieve lean body mass.

However, a new study published by the National Strength and Conditioning Association showed that unilateral and bilateral lower body exercises (for example Bulgarian squat vs. back squat) produced similar neuromuscular and hormonal responses.

Would this be the same working the upper body?

In another study, subjects performed five different upper body exercises one arm at a time or both at the same time. When important hormones for exercise adaptations were measured, including growth hormone, testosterone and cortisol, the bilateral exercises produced the highest responses.

Think big

It seems that what matters – in terms of producing comparable endocrine and metabolic responses when performing unilateral or bilateral exercises – is the amount of muscle mass that is being used in each exercise.

This may explain why when comparing a Bulgarian squat lunge to a back squat, because they both work the big muscles of the legs in addition to the core, they produce similar neuromuscular levels of excitation and hormonal responses. In contrast, when using the smaller muscles of the shoulder, such as when performing a single arm shoulder raise vs. a two-arm shoulder raise, the responses are not comparable.

To get an athletic frame – lean and toned – maximizing the anabolic response is a must. But this doesn’t have to be achieved at the expense of creating muscle and joint imbalances that may increase the risk of injury in the future.

Unilateral workout

So, how we can work one extremity at a time while getting comparable neuromuscular and endocrine responses to bilateral exercises?

The following routine combines unilateral lower and upper body moves that will allow you to focus on one side at a time while engaging significant body mass. These exercises will increase the core muscle involvement for added stabilization.

  • Perform these three exercises as a circuit – one exercise after another without rest
  • Rest at the end of each circuit for 60-90s
  • Repeat the circuit 2-3 times performing 8-10 reps per side
  • Do a dynamic stretching warm-up
  • Do this routine two times a week on alternating days

Marta Montenegro is an exercise physiologist, certified strength and conditioning coach and master trainer, who teaches as an adjunct professor at Florida International University. Marta has developed her own system of exercises used by professional athletes. Her personal website,, combines fitness, nutrition and health tips, exercise routines, recipes and the latest news to help you change your life but not your lifestyle. She was the founder of nationally awarded SOBeFiT magazine and the fitness DVD series Montenegro Method.

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