The Truth About Muscle Pump and Hypertrophy

Does The Pump Even Matter?

Is the pump itself a hypertrophy stimulus? It’s debatable. The current consensus is that the main trigger for muscle growth is mechanical tension created by the muscle fibers when they’re contracting hard. This activates mechanoreceptors on the muscle fibers, which activate growth pathways leading to an increase in protein synthesis and muscle growth.

The pump doesn’t factor into that equation. However, that doesn’t mean that it plays no role.

Growth Factors and the Pump

The pump is associated with the release of growth factors (mechanical growth factors like IGF-1) inside the trained muscle. The accumulation of lactate and reduction in oxygen uptake by the muscle are stimuli that release those growth factors. In a sense, the more a muscle “burns” and gets swollen, the more growth factors you get.

Now, by themselves, these growth factors aren’t a huge hypertrophy stimulus. But when combined with mechanical tension (which will occur when the growth factors are released due to resistance training), those growth factors do increase hypertrophy stimulation.

An analogy: Mechanical tension is the soil and water; growth factors are the fertilizer.

• If you put a seed in fertilizer without soil or water, the plant won’t grow.
• If you put the seed in soil and provide water, the plant will grow.
• If you put the seed in soil, provide water AND add fertilizer, the plant will grow faster.

Intramuscular Pressure and Fascia Stretching

An increase in intramuscular pressure (the pump) – which is an accumulation of fluids and metabolites inside a muscle while you train – contributes to and initiates metabolic processes that lead to muscle growth. (1)

There’s also a theory that stretching the muscle’s fascia can induce hypertrophy. The fascia is a very active tissue that sends a lot of information to the rest of the body. It’s possible that creating a significant pump, which temporarily increases the volume of the muscle, could stretch the fascia surrounding that muscle which might initiate certain growth pathways (an increase in IGF-1 receptor sensitivity might be involved).

So, it’s not a stretch to theorize that the pump could be a secondary stimulus for growth, which is not insignificant.

The Pump as Feedback Mechanism

Another benefit of the pump? Getting instant and direct feedback about whether you’re using the target muscle to do most of the work.

The pump is, in large part, the result of the production of metabolites that occur during muscle contractions. If you have a pump, it’s a good indication that the specific muscle was significantly involved in the exercise: the accumulation of metabolites indicates that this muscle contracted hard and for several repetitions.

By extension, if you don’t get at least a mild pump in the targeted muscle, then it might indicate that this specific muscle didn’t contribute much to the movement.

Note: Low-rep sets won’t typically cause a large pump because they rely mostly on the phosphagen system, which will not lead to the same lactate/hydrogen ion release as moderate or higher sets. So, consider that when evaluating an exercise.

The Mind-Muscle Connection

This is a misunderstood concept. It’s not some mythical voodoo by which you use the power of your mind to make a muscle contract harder.

It simply refers to properly feeling/sensing the tension present in a muscle when you’re training it. See, when a muscle fiber produces tension, it also sends signals to the nervous system, which makes the nervous system “aware” of what’s going on with that muscle.

As such, “feeling” a muscle while you’re training is not inconsequential; it means that you are producing tension with it. And the more you feel it, the more tension is likely being produced.

On the other hand, if you can’t feel a muscle while training it, it’s unlikely that you’re optimally contracting it and imposing maximal tension – the main muscle growth stimulus.

If you “feel” tension in muscles other than the targeted one, it’s fair to assume that either that exercise (or the way you’re executing it) isn’t loading and stimulating that target muscle even if, on paper, it’s the best exercise to do the job.

What About Muscle Soreness?

First, get this straight: a productive workout doesn’t necessarily lead to muscle soreness. That lack of soreness is not an indication of a lack of gains. It’s not necessary for growth, and it’s not a hypertrophy stimulus.

In fact, excessive soreness could mean that you created too much muscle damage, which can lead to fewer gains. Soreness lingering for more than two days is likely an indication of an excessive amount of muscle damage which will lead to slower gains. The fibers are so damaged they can’t be repaired; they need to be regenerated, which is a longer process.

That said, a proper level of soreness or tenderness in a muscle the day after you train can give you another clue whether the exercise you used was effective at targeting that muscle. Soreness within a muscle is at least an indication that this specific muscle was loaded intensely. So while it’s not necessary to get sore, when it happens, it provides a clue of whether or not you’re choosing a good exercise.

The Take-Home Message

Proper training requires you to constantly evaluate whether what you’re doing is effective or not. For exercise selection, there are several tools you can use. The pump, feeling the tension when training and post-training soreness are all valid clues. This has been used for decades. The best bodybuilders throughout history relied on these signs to select their exercises.

However, with the current trend of “science-based” training, it has been relegated to the kingdom of Broscience, with the negative connotation that comes with it. Heck, it’s often ridiculed despite the fact that for years it has been a key element in exercise selection… and it worked.

You should use all the tools at your disposal to make the best exercise choices. Analyzing the biomechanics of an exercise and EMG data are very useful tools. But so are the immediate feedback you get when doing the actual training.

Personally, if I get a poor mind-muscle connection and minimal pump from an exercise, even if on paper it’s the best biomechanical match for a muscle, I’ll look for a different movement or try to fix my pattern so that I can feel the muscle.

So yes, muscle “feel” matters. Don’t disregard it.

Reference

1. Morita1 N et al. Influence of stretch and pressure as mechanical stresses on skeletal muscle. J Phys Fitness Sports Med. 2013;2(3):347-350.