Are Light Weights Worth Using?

Or are they just a marketable illusion of exercise?

Worth the weight?

Fun fact that you probably already know, but might not have thought about in this context:

Muscle growth depends primarily on taking an exercise to failure or near failure, rather than on whether you use light or heavy weights.

In particular, studies (cited in the video) showing similar muscle growth from light and heavy weights typically require participants to train to failure or near failure, so both approaches can be effective under those conditions.

Note: that’s failure, not fatigue. To clarify, fatigue is the burning sensation and discomfort that develops during exercise, whereas failure is the point where your working muscles can no longer produce enough force to complete another rep.

This means that the burning sensation associated with lactic acid accumulation isn’t what stimulates muscle growth, so feeling a strong burn alone doesn’t mean an exercise is effective.

To illustrate it:

• Light weight example: using light dumbbells (as used for the reverse lunges in the video) may produce intense burning and discomfort, but if you stop because the sensation becomes unpleasant before your muscles actually fail, you’ve reached fatigue rather than failure, and will not get stronger.
• Heavy weight example: using heavier dumbbells typically brings you to failure in fewer reps, with your movement slowing and your muscles becoming physically unable to complete another repetition despite maximal effort.

Common mistake to avoid: if a workout prescribes a certain number of reps, using weights that allow those reps to feel easy is unlikely to stimulate significant muscle growth, because the set doesn’t approach failure. So this is a good example of how following instructions can easily lead you astray (and incidentally it’s why at 10almonds we very rarely include sets-and-reps numbers in our exercise explanations, because even if they’re often included in videos, in reality they need to be personalized to you).

All of which means that in practical terms, usually heavier weights will actually be the easier as well as more effective workout, because of being able to reach failure more quickly, and thus not undergoing the psychological exertion of having to take the time to push out 324 reps of something to get a result.

Counterpoint not mentioned in this video: one way that lighter weights definitely have a benefit is in training the initial brain-muscle neural connection, so that the correct muscles get correctly recruited when you increase the weight (as opposed to the body compensating with a nearby large muscle group that can handle it, thus allowing the intended-to-be-trained muscle to get off easy without doing the work you want it to do).

For more on all of this plus visual demonstrations, enjoy:

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Want to learn more?

You might also like:

Save Your Back With Strong Glutes ← Personal trainer Elisi Wolf explains more about that brain-muscle neural connection we mentioned, and it’s why she coaches people through using light weights in a certain special way first, not because using the light weights not-to-failure will build muscle, but because it lays the proper neural foundation for the heavier weight training that follows. The example she uses here is glutes, whence the title, but the same process goes for whatever muscles you are intending to train.

Take care!