And that’s a good thing. The benefits of resistance training are countless and thoroughly proven: It extends longevity¹, increases bone mass², reduces stress³, improves cardiovascular health⁴, and so on (we could go on for a while!).

But when it comes to the “best” strength training plan, things can get confusing. Should you lift heavier weights, or aim to do more reps and sets? How often do you really need to lift to see results? Different influencers will give you all kinds of conflicting advice on what you should or shouldn’t do, while various ads bill themselves as the next greatest thing. For a long time, even science seemed to offer murky answers.

“The research on the topic has not been all that clear with many papers sending mixed signals as to whether reps or weight matter more for developing strength versus muscle mass,” says Dustin Willis, DPT, a professor at West Coast University.

However, a new, potentially landmark research paper⁵ that reviewed over 1000 studies—the largest of its kind to this date on this topic—gives us increased insight into the matter.

To start off, the paper confirmed what is already well-known about resistance training: Compared to no exercise, almost any combination of sets and reps, no matter how heavy or how often you’re lifting, will lead to increases in muscle strength and muscle size. That’s very likely not news to you!

Diving deeper, the researchers found that to increase muscle strength, the training programs that involved multiple sets or heavier weights were most effective. And those programs that included both multiple sets and heavier weights were the highest rated.

But when the goal was to build bigger muscles (what scientists call hypertrophy), how much weight you’re lifting wasn’t all that important. Instead, the researchers found that multiple sets and multiple days of training per week had the greatest impact on muscle size.

What’s more, the researchers also explored the concept of “training to failure,” or doing as many reps as you can until you can’t do any more, as a means to build muscle size. Interestingly, they found it typically made no significant difference. (Though, there was a caveat that this approach could potentially be useful for more advanced lifters.)

One other notable finding had to do with the “minimum effective dose,” or the least amount you have to lift to see some results. To gain strength, they found you needed to do resistance training for at least two sets or two sessions per week, while for hypertrophy the minimum effective dose was resistance training for at least two sets and two sessions per week.

To put it all together:

If your goal is to get stronger, focus on lifting heavier weights (of course, do this in a methodical and progressive manner) for multiple sets. The minimum amount to get stronger is at least two sets or at least two training sessions per week, using the same muscle groups.

If your goal is to get bigger, don’t worry about how heavy you’re lifting, but focus on lifting weights more frequently (also in a methodical and progressive manner) for at least two sets and two sessions per week focusing on the same muscle groups. If you’re a beginning lifter, then “training to failure” isn’t necessary but if you’re more advanced, it’s potentially useful to kickstart more muscle growth.

Other than that, there’s no need to overthink it! Focus on moves you enjoy, and you’ll see the #gains follow.