In the physique/aesthetic based training world there is a popular opinion that you should vary exercises or even whole programs regularly to ‘confuse’ the muscle. You know, keep them guessing…

The theory is that frequently changing the stimulus to the muscle, by varying exercise selection, will make the muscle have to constantly adapt and thereby lead to new growth.

While there is some merit to this theory, what if the opposite were true? That muscle is actually not as effectively built when you’re not familiar with a movement...

A study by Chilibeck et al in 1998 can provide some insight. [1] They took 20 participants and had them perform the bench press, leg press and bicep curls for 20 weeks. At the mid-point and end point of the study, measurements of hypertrophy and strength (1RM) were taken. At the mid point of the study (10 weeks) there was a significant increase in arms growth, as well as strength, while there was no significant growth in the trunk or legs. However, by the end of the study hypertrophy in the legs and chest had become apparent.

What does this mean?

The delay of growth in the chest and legs may be due to the exercises being compound movements which have been suggested to involve longer initial neural adaption when compared to more simple single joint exercises (eg.bicep curls) and that this may have resulted in delayed growth effects.

Basically, early strength gains in training programs are largely down to neurological improvements (eg. Increased muscle fibre recruitment, motor unit firing rate and synchronicity) and occur before much muscle growth. [2]

The authors concluded that training with more complex exercises (bench and leg press) caused delayed muscle hypertrophy when compared to a less complex exercise (arm curl).

This study indicates that as we become more proficient at a movement we are able to focus more on progressive overload specifically on the targeted muscles and see greater hypertrophy. [3]

So, if your goal is to get jacked, then it may be worth spending some time becoming an expert in the compound movements that will drive muscle growth.

Lifting is just like any other skill, you must spend the time performing the movement (with proper form) to become a master. You think Mr. Miyagi was born with the ability to catch a fly with chopsticks!?

He wasn’t.

He started with stationary rice, just like the rest of us, and progressed from there.

The point is, it can be counterproductive to frequently swap exercises or programs because you’re restricting your ability to master the complex movements and reap that sweet hypertrophy nectar.

“So I’m doomed to a life of the same workouts!?”

No, not at all.

As always, there is another side to the story.

Variety still has a place and can be important for optimal muscle growth.

Compound exercises, as their name suggests, incorporate multiple joints and muscles in order to perform the movement. But this doesn’t necessarily mean that the given exercise is the best or most efficient way to train each of the muscles involved.

For example, while triceps are incorporated during the bench press, that doesn’t mean that bench press is the best exercise for full development of the triceps.

Another example would be squats for glute development. I’m sorry ladies (and lads) but all those memes about “she squats bro ;)” are selling your Beyoncé booty goals short. Yes, the glutes are working during a squat but for optimal booty development direct glute targeting exercises such as weighted hip thrusts will enhance your results. [4]

All these women implemented heavy hip thrusts in order to improve their glute development. Image courtesy of Bret Contreras

For that reason, some accessory exercises can be vital in the pursuit of aesthetics.

In fact, this was seen in a 2014 study that compared groups performing varying resistance exercises. [5] Specifically, one group only did Smith machine squats (erghhh, I cringe just writing that), and other groups performed the Smith machine squat as well as leg press, deadlifts and lunges. Both groups performed the same total number of reps and sets, so only the number of exercises changed.

Total muscle growth between groups was the same. However, the authors found more uniform growth in all heads of the quadriceps in the group with multiple exercises. This indicates that if your goal is symmetrical development (which it should be) then variety in exercises can be important.

This makes sense.

We know that muscle is often compartmentalized. [6] Meaning that different parts of the muscles are preferentially activated based on joint positions and angles. [7]

Think incline bench for the upper chest.

So how do I implement variety in my training?

Via accessory and isolation exercises.

This way we can keep the heavy compound movements steady throughout training programs ensuring we spend the requisite hours of skill development needed to master the movement and get the most muscle growth benefit.

Meanwhile, by including and varying accessory/isolation exercises we benefit via:

Their simple nature tends to be easier for the body to learn and therefore we can see adaption and muscle growth quicker than compounds.
They offer a way to ensure balanced development of all muscles and even within different parts of the same muscle.
They can help mitigate any weak points that may be limiting progression in your compound lifts.

Practical Applications:

Based on the above evidence and anecdotal experience with clients we can make a few basic guidelines.

For hypertrophy, a good starting point is generally to choose 1-2 compound and 2-4 isolation movements for each muscle group.

In order to maximise skill development in more complex movements such as the squat, deadlift etc. keep them or similar variations constant through your programs while isolation movements can be rotated more frequently if and when desired.

References:

1) Chilibeck, P.D., et al., A comparison of strength and muscle mass increases during resistance training in young women. Eur J Appl Physiol Occup Physiol, 1998. 77(1-2): p. 170-5.

2) Sale, D.G., Neural adaptation to resistance training. Med Sci Sports Exerc, 1988. 20 (5 Suppl): p. S135-45.

3) Fry, A.C., The role of resistance exercise intensity on muscle fiber adaptations. Sports Medicine, 2004. 34(10): p. 663-79.

4) Contreras B, Vigotsky AD, Schoenfeld BJ, Beardsley C, Cronin J. A Comparison of Gluteus Maximus, Biceps Femoris, and Vastus Lateralis Electromyographic Activity in the Back Squat and Barbell Hip Thrust Exercises. Journal of applied biomechanics. 2015 Dec 1;31(6).

5) Fonseca, R.M., et al., Changes in exercises are more effective than in loading schemes to improve muscle strength. Journal of Strength and Conditioning Research, 2014

6) Woodley, S.J. and S.R. Mercer, Hamstring muscles: architecture and innervation. Cells, Tissues, Organs, 2005. 179(3): p. 125-41.

7) Glass, S.C. and T. Armstrong, Electromyographical activity of the pectoralis muscle during incline and decline bench presses. Journal of Strength and Conditioning Research, 1997. 11(3): p. 163-167