Heavy Weights Low Reps or Light Weights High Reps?

Finding the perfect lifting routine for building muscle can be hard.

Sure, you know that you’ve got to lift things up and put them down. That’s the easy part.

But how you do it - whether you focus on lifting heavier weights, or hitting more reps with lighter weights - is more difficult to figure out.

If you go to the gym and watch what the regulars are doing, you might get an even split between people doing heavy weight and low reps vs. lighters weights and more reps.

So, which is best? Does it even matter?

Read on to learn more.


How Does Muscle Grow?

If muscle growth is your main workout goal, you should know how muscles actually grow to know the best type of workout to meet your goals.

First, we should mention that it takes both training and nutrition to achieve optimal muscle growth. However, in this article, we’re only discussing the training side of things.

You get muscle growth when you put the muscles through hypertrophy

This is when muscle fibers sustain small tears or damage due to stress, such as from lifting heavy weights.

Each time your body repairs these damaged muscles, it makes them a little bigger and stronger.

The best way to achieve hypertrophy is through resistance training

Resistance training means an exercise that pits a muscle against external resistance, such as a heavy dumbbell, kettlebell, or resistance band.

Consistent resistance training, achieving hypertrophy while allowing muscles to heal in between workouts, will almost always lead to larger and stronger muscles. 

To increase or speed up muscle growth, focus on increasing your workout volume.

What is Workout Volume?

Workout volume (or training volume) is the total amount of work you get through in your workout.

You’ll generally want to measure workout volume over a period of a week or a month. Add up your total volume over this time, of various variables related to your type of workout.

For strength or resistance training, this may be:

  • Reps
  • Sets
  • Weight

For example, if you’re bench pressing four sets of 8 repetitions with 150 lbs weights, then you can calculate your volume as the following:

  • 4 X 8 X 150 = 4800

You should look to increase that total number progressively during the following weeks and months as you add more volume.

If you’re doing cardio or aerobic training, you may also measure distance or time as part of your total workout volume.

The Link Between Workout Volume and Muscle Growth

Understanding your total workout volume is key to achieving optimal muscle growth.

In a nutshell, you want to put your body through as much work as possible (leaving yourself enough space for recovery, of course). 

Over an extended period, the more work you do - whether it’s more reps, total weight, or a mixture of both - the more you should expect to progress.

It’s also important in terms of “progressive overload”. 

As Dr Andy Galpin discusses in the following video, you need to progressively increase your training volume over time to improve physically (such as getting bigger or stronger).

This can be in terms of lifting more total weight, or lifting the same weight more often. As long as you keep increasing your total workout volume.

Now, on to the question of what the best way is to fill out your workout volume - a lot of repetitions, with lower weight, or fewer reps, but heavier weight in each rep.

Low Reps and Heavy Weights - Pros and Cons

The first option is to focus on lifting heavy, with fewer repetitions.

For example, you might lift somewhere close to the maximum you can lift safely (say 80-85% of your max) for 5-6 reps each set.

Lifting heavier weights is best for building greater overall strength. Strength and muscle mass don’t always come together, but they are correlated.

Heavier weights activate Type 2 muscle fibers, also known as “fast-twitch” muscle fibers. These muscle fibers translate to greater strength and hypertrophy - though, on the downside, they tend to fatigue faster.

This option can also be good if you’ve got a shorter time to exercise since you can get more total weight in fewer reps/less time.

The main con of lifting heavier is the greater risk of injury or suboptimal gains due to poor form. If the weight is too much to do with correct form, you’ll want to drop down to a lower weight.

Ideal Rep Ranges 

General rep ranges of this option would be four sets of 6-8 reps or 5 sets of 5 reps each.

You’ll want to focus on weights close to (but not 100% of) the total weight you can safely lift for that exercise.

You may also need to more rest between each set when you’re lifting heavier weights, to give the muscles more time to recover.

High Reps and Lighter Weights - Pros and Cons

On the other end of the scale, you can choose to lift lighter weights, but do more reps in each set.

Lighter weights don’t activate Type 2 muscle fibers, so they’re a little worse for building strength. They’re also a little worse, in a vacuum, for hypertrophy (muscle growth).

However, the advantage of lighter weights is that your muscles are slower to fatigue, and you’ll be able to put out a lot more reps.

This can mean you add more to your total workout volume, leading to the same levels of muscle growth over time as with heavier weights.

There’s also the advantage of focusing on perfect form, which is just as important (perhaps more) than the total amount of weight you lift.

Lifting lighter weights with higher reps is also better for building muscular endurance and cardio, which may help you exercise for longer in the future - which, again, will result in a higher total workout volume.

Ideal Rep Ranges

For lighter weights, you’ll want to do 3-4 sets of 10-15 reps per set.

You can even go further than this, with 15+ reps per set. But generally, you want to get through 10 at a minimum.

As for weight, go for about 50-60% of your one-rep max.

Which is Better for Muscle Growth?

The short answer is that both options can achieve hypertrophy, and as a result, muscle growth.

In isolation, high-weight, low-rep workouts will build muscle more effectively. That being said, you may see more gains over a longer period of time with lower weights, due to increased cardio and endurance, and thus total workout capacity.

But instead of thinking about whether you should be doing high weight/low reps or low weight/high reps, think about your total workout volume and progressive overload.

Consistently increase the weight you lift, or the number of reps, or both.

For example, if you hit 50 reps of 100lbs each in a week for one exercise, try to hit 55 reps of 100lbs, or 50 reps of 105 lbs, the next week.

Keep increasing the total volume, and you should see growth over time.

How Many Sets for Each Muscle Group Per Week?

There’s not really an optimal number of sets you need to hit for each muscle group in a week.

Ideally, you’ll work with each muscle group at least once per week. More is even better.

However, the most important thing with hypertrophy is recovery. The recovery period is when your muscles actually get bigger, and it takes 48-72 hours for muscles to fully recover after resistance training.

That means it’s not really feasible to train a muscle group more than twice per week, factoring in recovery time.

As for the number of sets, it can vary greatly depending on the weight you lift, and number of reps per set. Again, focus more on total workout volume and progressive overload.

Don’t Be Afraid to Mix It Up

One final point is that there’s no need to choose one weight/rep range and stick with it.

You’re not going to hurt your gains by doing a different combination from one workout to the next, or do a few weeks on low/heavy, then a few weeks on light/high reps.

In fact, this might even be better since you will get a better overall mixture of strength and endurance gains than if you stick to one formula.

But specifically for hypertrophy, you just need to make sure you’re training regularly, increasing your total load, and giving your muscles time to recover between workouts.