The Three Fundamentals of Building Muscle, Part 2: Intensity

by Aug 22, 2017Blog, Muscle Gain, Strength and Conditioning

Intensity refers to the percentage of your 1 rep max on the bar. Before we get any further, no you don’t have to know your 1RM for every lift. Or any lift unless you’re not a competitive power lifter.


There is an inverse relationship between intensity and volume, so the higher the intensity the lower the volume. Higher intensities are more stressful on our central nervous system (CNS), so we need to think about how and when to use them. What does this mean for our training then?

Well, think of the intensity in training sessions like being in a race car. There is a sweet spot where changing gears is seamless, the green zone. There is also a zone under that where you could change gears but it would take a hell of a lot longer to do so again because you weren’t putting your foot down enough, the yellow zone. Finally, there is all our burn-out where your foot is to the ground and you’re not changing gears, the red zone.


You’ve probably guessed it by now, you want to be in the green zone. However, that’s not to say the other zones don’t have a place.

There is a sweet spot for hypertrophy between about 60-85% of your 1 rep max where most people will experience the most muscle growth.


However, going over that 85% allows you to adapt to a different kind of stimulus and experience heavier loads. Also, studies have shown that when it comes to hypertrophy similar results were achieved with 30% as 80% as long as contractile failure was achieved (basically this means as long as you fatigue the most muscle fibres possible, you’ll grow). You CAN achieve hypertrophy with lighter loads, but you may well miss out on a lot of the benefits of using moderate to heavier loads.


The main point to keep in mind when it comes to intensity is the quality of your movement. If you move like a crumpled-up car bonnet under a squat, you’re lifting too much. Training is NOT competition, so don’t think of it like that. Train to get better at something, not just smash your PB every time you walk in the gym. It’s about progressive overload, so be progressive and leave your ego at the door. You have to earn the right to lift heavy. Get your form right first with more reps at a lower intensity and gradually build up over time.

Take away points:


The higher the intensity, the more CNS stress. The more CNS stress, the more recovery time needed.

Spend most of your time between 60-85% of your one rep max doing 5-12 reps per set

Plan periods of time in your training cycle where you will ‘overreach’ and go higher than 85%, dropping the reps below 5. For example in an 8 week block you may start the main lifts at 70%, gradually building to 95% for a training max in the final week before de-loading in the following week at 60%.

Isolation movements can be done at a much lower intensity, to allow for less stress on the nervous system but still achieve muscular fatigue.

There is a place for all intensities in training.

Training is not competition, form is always first.

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