How Many Reps Are Needed to Build Lean Muscle?

A wide variety of reps can help build lean muscles.
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There are many rep ranges that can help you build lean muscles. Some organizations, such as the American College of Sports Medicine, believe that the ideal rep range for mass is six to 12, but it's possible to build muscle using a very wide range of repetitions.



A wide range of reps can be used to build lean muscle, as long as you're increasing the weight, the number of sets or the number of repetitions over time.

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Benefits of Building Muscle

Building lean muscle can boost your self-confidence, make you stronger and help you live a longer, healthier life. You naturally lose muscle mass as you age, but building muscle through resistance training can counteract that.

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A 2016 study published in Biogerontology shows that you can live a longer, healthier life if you build or maintain muscle mass as you age. Maintaining muscle mass and strength helps maintain your independence.

Resistance exercise, whether that means bodyweight training or using dumbbells, cables or barbells, helps build muscle. You can think of your muscles as pieces of rope. There are small fibers, called myofibers, that join together to form bigger fibers. These fibers join together to create even bigger fibers, similar to the way a rope is made from small threads that wrap around to create larger threads.

When your muscle fibers become thicker and stronger, it's called myofibrillar hypertrophy, meaning the actual muscle fiber is building up. There's another form of muscle growth too, called sarcoplasmic hypertrophy.


Your muscles are made of protein and fluids that contain everything they need to grow, regenerate and contract. Sarcoplasmic hypertrophy is growth of the cells and fluid that muscles need, rather than growth of the actual muscle fiber. Both types of muscle growth contribute to lean muscle mass.

Read more: Define Lean Muscle

Best Rep Range for Mass

To make your muscles bigger, you need to stress them. It's a slow process of working your muscles in the gym to the point where they're slightly damaged or exhausted, rebuilding them, working them again and so on. Sometimes, this process is so slow that you wonder if your workouts are good enough to make your muscles grow.


At the same time, you have to make sure that you're not working too hard. If you do too much at the gym, you can injure yourself or impair your body's ability to recover, which is known as overtraining.


That's why it helps to have a set goal when you go into the gym. By sticking to a plan, you give yourself something to shoot for. Some organizations, like the American College of Sports Medicine and the National Strength and Conditioning Association, suggest that the ideal rep range for mass is six to 12.


Below six repetitions lies the rep range for strength, and above lies the rep range for endurance. That means you're in between the strength and endurance ranges when your goal is to grow the muscle.

While it helps to have a standard rep range for mass of six to 12 repetitions, it doesn't mean that there's only one rep range in which you can build muscle. In fact, it might not even be the best rep range for you.


An October 2015 study published in the Journal of Strength and Conditioning Research looked at two different methods of building muscle: heavy weight and low reps versus low weight and high reps. The heavy weight and low reps group used a load that was challenging for eight to 12 reps. The low weight and high rep group used a weight heavy enough for 25 to 35 reps.

The researchers have found that the group that did eight to 12 reps got stronger, but they gained the same amount of muscle as the group performing 25 to 35 repetitions, which is a far cry from the recommended six to 12 repetitions.


This study shows that there's more to building muscle than using a certain rep range. Indeed, a January 2019 study published in Medicine and Science in Sports and Exercise shows that muscle growth comes from an increase in training volume, not necessarily the number of repetitions performed.

In the study, the researchers discovered that a higher training volume creates more increase in muscle mass, although this increase doesn't necessarily lead to greater strength. In other words, it's possible to use high reps and light weight to build muscle, but you won't get the added benefit of getting stronger.



Training volume is the number of sets, reps and weight you use for an exercise. You multiply those three numbers together to get your total training volume for a workout. For example, if you do three sets of 10 repetitions for bicep curls using a 10-pound weight, your volume is 300.

You can play with any of those three numbers to increase your training volume. For example, adding one more set of 10 repetitions would bring your volume up to 400. Adding two repetitions per set would add 60 to your volume.

While it might seem tedious, try calculating your training volume from your last workout for each exercise. Then, try to beat it slightly in your next workout. You'll see how even a slight increase in repetitions increases your volume and workout difficulty.

If you want to use the same number of reps for every workout, you can up the weight or number of sets. The number of repetitions you do isn't necessarily the cause of muscle growth, it's just one way to make the exercise harder. Your goal is really to add volume to the workout to continue challenging the muscle and forcing it to grow.

Sets and Reps for Mass

A May 2015 study published in the Journal of Strength and Conditioning Research showed a correlation between the number of sets performed and the amount of muscle gained. The subjects completed one, three or five sets per exercise. Every time the number of sets increased, the amount of muscle gained increased as well.

This study also points to total volume as the stimulus for muscle growth. As the number of sets increased, so did the total volume. If your goal is to grow your muscles, you should focus on increasing volume in any way you want. If doing more reps is the way you prefer to increase volume, then higher reps will help you increase muscle mass.

Some might argue that you need to train to failure if you want to gain muscle, but that doesn't seem to be the case. Training to failure means that you lift weight until it's physically impossible to complete another repetition with good form. This style of training is intense, but it doesn't help you gain more muscle, according to a March 2015 study featured in the Scandanavian Journal of Medicine & Science in Sports.


Duration May Not Matter

The duration of each repetition doesn't seem to matter too much either. An April 2015 study published in Sports Medicine reviewed eight studies on the duration of repetitions and muscle growth.

Researchers observed that there wasn't much difference in whether the reps were performed for between 0.5 and 8 seconds. They even noted that reps lasting longer than 10 seconds resulted in less muscle growth. In other words, you don't need to slow down your repetitions to gain muscle.

Increasing muscle mass isn't the end-all be-all of strength training. Gaining strength not only helps with everyday life but can help you prevent falls and maintain independence as you age. When it comes to getting stronger, volume doesn't matter so much — but the amount of weight you lift does.

There's a relationship between the number of reps vs. weight you use. In fact, you can use the number of reps you can do in a set as a barometer for how heavy you want the weight. That's why a rep range of one to five repetitions is generally considered the best for gaining strength. Lower rep ranges let you use heavy weight without exhausting yourself.

Read more: The Best Way to Gain Lean Muscle Mass

Rep Range for Building Strength

While you can use high reps to build muscle, low reps are best for building strength, according to a May 2017 study published in Frontiers in Physiology. Researchers credit the difference between light and heavy weight training to changes in the nervous system.

Muscle grows at about the same rate, as long as volume is matched, whether you use light or heavy weights. Making your muscles bigger doesn't necessarily make them stronger. Training with heavy weights seems to stimulate the nervous system more than light weights.


When your muscles need to contract, your brain or spinal cord sends a signal down to the muscle to make it contract, then relax. Heavier weights require more activity from the nervous system to recruit more of the muscle into the movement.


Training with heavy weights increases the amount of nervous system activity, making you stronger without necessarily increasing your muscle mass.

Protein for Muscle Gain

While the type of training you do is important, keep in mind that you have to fuel your body with protein to help it rebuild tissues. Lifting weights causes micro-trauma to your muscles, from which they have to heal. During the healing process, the muscles actually grow.

According to a March 2018 study published in the British Journal of Sports Medicine, protein is essential if you want to build mass. Your muscles are partially made of protein, which is the foundation of muscle fibers. You should consume roughly 1.6 grams of protein per kilogram of body weight per day, according to the above study. More than that has no significant effect.

Researchers used protein supplements as well as protein from food sources in the study. Try to get all your protein from food sources like chicken, beef, beans and nuts before you rely on supplements. These foods have extra vitamins and minerals that some protein supplements lack.




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