What’s Better For Muscle Building: Heavy Weights or Light?

There are an infinite number of ways to approach your training program. You can add or subtract weight, increase or decrease the number of sets and repetitions or shorten your rest periods. You can experiment with different exercises or training on different days of the week.

Workout classes like Pilates use very light weights, typically below 10 pounds, but very high repetitions. Powerlifting, on the other hand, is a weightlifting sport that uses heavy weights for one repetition.

However, the most important factor in making your muscles grow seems to be training volume, according to a 2018 study published in Sports Medicine. The researchers found, “volume is the most easily modifiable variable that has the most evidence-based response with important repercussions, be these muscle hypertrophy or health-related outcomes.”

You can find your training volume for an exercise by multiplying the weight you used by the number of sets and reps performed. For example, if you use 100 pounds on the bench press for 3 sets of 10 reps, your total volume is 3,000 for that exercise. Rather than focusing on how much weight you use or agonizing over the correct number of sets and reps to grow your muscles, you can focus on volume.

Previously, it was thought there was one optimal rep range to grow muscle. This was known as the “hypertrophy rep range.” Hypertrophy is a term for muscle growth. For example, the American College of Sports Medicine recommends doing 8–12 repetitions to grow muscle.

This rep range is practical because it’s a balance of heavy weight and high reps. With very heavy weight you can only do a few repetitions, which makes it harder to increase your volume. If you perform 20 or more repetitions, it’s hard to increase the weight you use. However, there’s no perfect combination. As long as you can increase your volume, you can grow more muscle.

To increase your volume you can change the weight, sets or reps. You can even change all three at once. The goal is to increase your volume over time. For example, a 2015 study published in the Journal of Strength and Conditioning Research had subjects perform either 1-, 3-or 5-sets of an exercise. They found that as the number of sets went up, the subjects grew more muscle. More sets of an exercise means more volume.

You can also add workouts to your weekly schedule to increase your training frequency. If you only bench press once per week and find it hard to fit all of your volume in on one day, try spreading it out over two workouts. A 2016 study published in Sports Medicine found splitting your workouts into two days per week led to more muscle growth than one day, even if you use the same amount of total volume. Just be sure to give yourself at least a day or two of rest in-between.

Volume is the key for muscle growth, but the same can’t be said for strength. If your primary goal for lifting weights is to get stronger, then you need to focus on lifting heavier weights over time. The amount of volume you use isn’t as important, according to a 2015 study published in the Journal of Strength and Conditioning Research. When your goal is strength, aim for sets with 6 or fewer repetitions. Using lower reps means you can lift more weight. Be careful and be disciplined about technique because heavier weight means more risk for injury.

Keep in mind: You can train for strength and muscle growth at the same time. When you’re lifting heavy weights, your repetitions will be lower so you’ll have to increase the number of sets you do. Your workout will probably last longer, but you’ll be able to accomplish two goals at once.

Whether you use light or heavy weights, you’ll have to decide how hard to push yourself in each set. Training to failure is a method used by some weightlifters to completely exhaust the muscle. Training to failure means repeating an exercise until you can’t lift the weight anymore and you have to stop. It’s a mentally and physically grueling style of training.

On one hand, training to failure is a good gauge for how hard you’re working. If you bench press 100 pounds and fail after 5 repetitions, you know your muscle was completely exhausted. If you bench press 50 pounds and fail after 25 repetitions, you know your muscle was equally as exhausted.

On the other hand, your risk for injury goes up because you can’t control the weight when your muscles fail. The risk might not be worth the reward. For muscle growth and strength, there doesn’t seem to be much benefit to training to failure. A 2015 study published in the Scandinavian Journal of Medicine & Science in Sports found going to failure wasn’t significantly better than the alternative for muscle size and strength. As long as you have the same amount of volume, you don’t need to push yourself to the point of failure.