All weights can build mass.

When we talk strictly about light weight and heavy weight training, we know that both styles can help you achieve the goal of muscle hypertrophy through different, yet very similar mechanisms. ⁣⁣⁣⁣⁣⁣
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Light load training (generally intended as a 16-30 RM) can produce similar hypertrophic adaptations to heavy/moderate lifting (6-8 RM) when performed to task failure, and the same can occur even with very light weights (as low as 20-30% of your 1RM) with the use of BFR cuffs. Why is that? ⁣⁣⁣
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Well, it all comes down to the level of effort that we are able to exert on a given set and the amount of mechanical tension that working fibers are able to experience.

In fact, when our effort exertion is very high/maximal towards the end of a set, the working muscle fibers are able to experience high level of mechanical tension, regardless of the actual weight on the bar. ⁣⁣⁣
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A very important component of hypertrophy is muscular fatigue, namely Peripheral Fatigue (different from CNS fatigue!) which occurs when we train in proximity or to task failure. This is when we generally see the barbell slow down in speed regardless of the effort we put in the execution of the repetition. ⁣⁣
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And it can happen with any given % of weights, the only difference will be the total volume needed to get there: heavier weights will be more ‘time efficient’ while light weights will take much longer. ⁣⁣
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In a sense, the weight on the bar doesn’t matter, but as Lyle McDonald puts it best, we use it as a “proxy for tension”, which helps us achieve the desired level of fatigue that is necessary to stimulate muscle growth. ⁣⁣⁣
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Training in proximity of task failure (not necessarily to failure) is key when wanting to maximize muscle growth, but *how often* we train to failure is also dictated by the amount of weekly training volume we accumulate.