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Anyone who hits the weight room regularly will inevitably face the question: Should you add more weight and do fewer reps, or use a lighter weight and do more reps? The debate has raged on for as long as people have argued over cake vs. pie (pie, obviously), but it’s not that simple.

The truth behind weight vs. reps lies somewhere in between. To paint a clearer picture, you have to understand why we ask this question in the first place.

Once you’ve been following a fitness program for a while, you’ll eventually hit a fitness plateau — that dreaded no-man’s land where your body adapts to your routine, and you no longer make progress. It sucks but it’s normal, and happens to everyone.

At this point, confusion about what to do next still lingers in the gym because weightlifting and its effects on our bodies are often misunderstood, says Tanner Baze, a certified personal trainer.

Hint: It involves a lot more than lifting super-heavy weight or banging out more reps in isolation. To get out of a rut, you actually need a combination of:

  • muscle damage: that hurts-so-good soreness after a workout
  • mechanical tension: the sheer strain of lifting something heavy
  • metabolic stress: that “burn” you feel from your muscle really working

Spoiler alert: Both heavy-weight and high-rep training check those three boxes to ultimately build strength. Either path you take, you’re making gains.Lasevicius T, et al. (2018). Effects of different intensities of resistance training with equated volume load on muscle strength and hypertrophy. DOI: 10.1080/17461391.2018.1450898

“If your goal is just to generally get stronger and more fit, choose one or the other,” says Nathan Jones, a physical therapist and Strongman competitor.

When you pile on the pounds, you typically lift on the lower end of reps; it’s as few as 1 to 5 for some people. That doesn’t sound like much, but by doing so, you’re increasing your overall maximum strength and greatly improving your ability to lift heavier weights.Schoenfeld BJ, et al. (2017). Strength and hypertrophy adaptations between low- vs. high-load resistance training: A systematic review and meta-analysis. DOI: 10.1519/JSC.0000000000002200

Most of that newfound superhero strength is because you’re improving your efficiency at a given exercise. Think of how your bank account grows when you minimize unnecessary spending. It’s like that, and the more you practice restraint with a budget, the easier it is to save.

Lifting heavy weights feels awesome, but it’s easy to get sucked into chasing the numbers and running into a wall. Eventually, you’ll reach a point where you simply can’t add any more weight. If you push it, you could compromise your form and put yourself at risk for injury.

“If you’ve increased your weight and now your form is breaking down, it’s best to drop the weight and then increase the number of reps you’re performing,” says Baze. Which brings us to…

In 2016, researchers divided athletes into two groups: heavy lifters who did 1 to 5 reps of moves like squats, lunges, and deadlifts, along with moderate lifters who did 8 to 12 reps of the same set of exercises.

At the end of 8 weeks, researchers found that those who lifted heavier weights with fewer reps had more strength. Makes sense. But it also turns out that the higher-rep, lower-weight folks had increased hypertrophy — aka more muscle-building activity. Schoenfeld BJ, et al. (2016). Differential effects of heavy versus moderate loads on measures of strength and hypertrophy in resistance-trained men. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5131226/

Bulging new muscles aside, when you lift lighter weights for more reps, you’re also getting stronger, just in a different way. You’re developing “muscular endurance,” or your ability to exert a certain amount of effort before you fatigue.

If you go this route, you’ll want to watch the number of reps and sets you complete. A 2015 study found that 8 to 12 reps per set was the sweet spot for maximizing strength, compared to the group doing 25 to 35 reps of each exercise (omg, who has time for that?).Schoenfeld BJ, et al. (2015). Effects of low- vs. high-load resistance training on muscle strength and hypertrophy in well-trained men. DOI:10.1519/JSC.0000000000000958

When you hit a plateau, adding reps instead of lifting more weight also allows you to focus on proper technique and form. You’ll end up working muscles as intended — called the mind-muscle connection — instead of relying on compensatory patterns (like letting your quads do all the work for your glutes).Calatayud J, et al. (2016). Importance of mind-muscle connection during progressive resistance training. DOI: 10.1007/s00421-015-3305-7

One downside to this technique is that it may make your workouts slightly longer, as you’ll spend more time doing more reps.

Why not try a little of both? For long-term progress and to keep things interesting, incorporate heavy-weight, low-rep training combined with light-weight, high-rep training. Switch up the weights, sets, and reps on different days or weeks. This technique is known as periodization.

“If you’ve been doing 5 sets of 5 squats and can’t add weight or get an extra rep, drop the weight and go to 5 sets of 8, or add weight and go to 3 sets of 5,” Jones says. Basically, imagine your sets and reps as a wavelength continuously going up and down.

There’s nothing inherently magical about changing things up this way. “Personally, I think it’s more psychological than anything,” Jones says. “Doing the same rep range every single time you lift gets boring. So, doing something different helps you maintain motivation, and subsequently, keeps your effort high.”

“There is no wrong decision here,” Jones says. When you lift more weight, add more reps, or do both appropriately with good form, you’re nudging your body toward continually improved fitness and strength.

That said, when you add weight or make changes, do so in small increments. Your goal is to squeeze big results from little changes. It also helps to include a proper warm-up and cool-down.

“The single most important factor in your progress is your willingness to work hard and exert high effort,” Jones says. “So long as you’re doing more of something over time, you will get stronger.”

Mixing it up a bit to keep yourself motivated and to see progress — whatever your goal — will go a long way.