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Light Weight vs Heavy Weights for Muscle Growth – Which is Better for You? (Science Based)

Settling the debate and talking about the myth surrounding it, once and for all.

The quest for achieving optimal muscle growth and strength has been a topic of immense interest among fitness enthusiasts and bodybuilders for decades. One of the most debated aspects in this realm is the choice between using light weights for high repetitions versus heavy weights for low repetitions.

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People often wonder which approach is superior for building muscle and gaining strength. Her we will dive deep into the light vs heavy weights debate, examining various scientific studies and insights from fitness trainer and Kinesiology graduate, Jeremy Ethier.

By analyzing the evidence and expert opinions, we aim to provide a comprehensive understanding of the best approach for muscle growth and strength development.

Light Weight vs Heavy Weights for Muscle Growth – Which is Better for You? (Science Based)

Jeremy Ethier, a renowned fitness trainer and Kinesiology graduate, is the co-founder of Built With Science. His YouTube channel has over 4 million subscribers and he delivers clear information with sound background research

Ethier combines his personal experience in the gym with expert interviews and relies heavily on scientific studies to support his arguments. This multifaceted approach allows him to present a well-rounded perspective on various fitness topics, including the light vs heavy weights debate you see below.

Source: Tanja Nikolic on Pexels

Debunking the Myth: Light Weight vs Heavy Weights for Muscle Growth

Traditionally, the bodybuilding community has propagated the belief that muscle growth primarily occurs when lifting heavier weights for a low number of repetitions. Conversely, using lighter weights for moderate to high repetitions was thought to be more suitable for endurance training rather than muscle growth. However, scientific research has challenged this long-held belief.

In 2012, a groundbreaking study compared the effects of heavy weights and lower repetitions with lighter weights and higher repetitions on muscle growth. Surprisingly, the study found that both approaches resulted in similar muscle growth when the training volume was equated for and sets were taken close to failure.

This finding debunked the notion that heavy weights were superior for muscle growth. Jeremy Ethier cites this study to highlight that the choice between light and heavy weights is not as straightforward as commonly believed.

Bethany Shadburne performs a heavy front squatSource: Photo courtesy of CrossFit Inc.

The Importance of Training Volume and Failure

Although both light and heavy weights can lead to muscle growth when training volume is equalized, the choice between the two is not entirely arbitrary. Training volume refers to the total amount of weight lifted during a workout session, calculated as the product of weight lifted, sets performed, and repetitions completed. Understanding the role of training volume is crucial in determining the best approach for muscle growth.

Moreover, the concept of training to failure plays a significant role in the effectiveness of both light and heavy weight training. Training to failure means performing repetitions until it is impossible to complete another repetition with proper form.

In high-repetition sets with lighter weights, training to failure can be more challenging due to increased metabolic stress. Some studies have shown that athletes training with lighter weights and higher repetitions may experience discomfort, and in extreme cases, they may even throw up during their workouts. On the other hand, heavy weights are easier to take close to failure, making it more convenient for strength gains and mechanical tension.

Best Science Based Dumbbell Biceps Workout for Size and ShapeSource: Andrea Piacquadio / Pexels

Combining Light and Heavy Weights for Optimal Results

Instead of focusing solely on one method over the other, Jeremy Ethier suggests a more balanced approach to achieve optimal muscle growth and strength gains.

  • Heavy weights with fewer repetitions are recommended for compound movements.

Compound movements involve multiple muscle groups and are essential for overall strength development. By using heavier loads in these exercises, individuals can efficiently target major muscle groups and promote mechanical tension, which is crucial for strength gains.

  • Lighter weights that allow for higher repetitions are beneficial for accessory exercises.

These exercises, performed after the compound movements, focus on specific muscle groups and contribute to the overall hypertrophic stimulus. Ethier emphasizes that higher repetitions with lighter weights can create a potent hypertrophic stimulus, similar to that achieved through heavy compound lifting.

The Role of Progressive Overload

Progressive overload is a fundamental principle in muscle building and strength development. It involves gradually increasing the demands on the muscles to stimulate growth and adaptation. While adding more weight to training is a common method of progressive overload, it is not the only way to achieve it. Progressive overload can also be achieved by increasing the number of repetitions, improving exercise technique, reducing rest periods, or incorporating advanced training techniques.

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To understand fully the debate over light weight vs heavy weights for muscle growth, with a science-based approach to see which is better for you, watch Ethier’s video in its entirety below.

In conclusion, the debate over light vs heavy weights for muscle growth has been a longstanding topic of interest in the fitness community. While the traditional belief favored heavy weights for muscle building, scientific studies have demonstrated that both light and heavy weights can lead to similar muscle growth when training volume and intensity are equated for. Jeremy Ethier, a respected fitness trainer and Kinesiology graduate, emphasizes the importance of balancing the use of light and heavy weights in training routines.

To maximize muscle growth and strength gains, Ethier recommends using heavy weights and lower repetitions for compound movements to target major muscle groups and promote mechanical tension. Additionally, incorporating lighter weights and higher repetitions for accessory exercises can provide a potent hypertrophic stimulus for specific muscle groups.

Ultimately, progressive overload remains a fundamental principle in muscle building, and individuals should focus on gradually increasing the demands on their muscles through various means. By adopting a well-rounded approach that combines both light and heavy weights, fitness enthusiasts can unlock their full potential and achieve their muscle-building goals effectively.

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Principles of Muscular Hypertrophy: Unlocking the Path to Muscle Growth

Muscular hypertrophy, the process of increasing muscle size, is a coveted goal for many fitness enthusiasts and athletes. To achieve this, several key principles come into play, each contributing to the overall growth and development of muscles. Let’s explore these essential principles and how they work synergistically to drive muscular hypertrophy.

  1. Progressive Tension Overload: The Foundation of Muscle Growth

At the core of muscular hypertrophy lies the principle of progressive tension overload. This principle dictates that muscle fibers must experience increasing levels of tension over time to stimulate growth. In practical terms, this involves progressively increasing the amount of weight lifted during resistance training. By consistently challenging the muscles with heavier loads, they adapt and grow stronger to meet the rising demand. However, progressive overload can be achieved through various means, such as increasing the number of repetitions, improving exercise techniques, or manipulating training variables like tempo and rest periods.

  1. Muscle Damage: Rebuilding Stronger Foundations

Muscle damage is an integral part of the muscle growth process. During intense training, muscle fibers undergo microtears and stress. These microtears are a natural response to the physical stress placed on the muscles during workouts. However, the true muscle growth occurs during the recovery phase. Adequate rest, recovery, and proper nutrition play crucial roles in this phase. When the body is given enough time and resources to recuperate, the muscles repair and grow back stronger, capable of handling greater stress in the future. Quality sleep and appropriate nutrition are essential components of muscle recovery and growth, as they provide the building blocks necessary for muscle repair and adaptation.

  1. Metabolic Stress: Pushing Muscles to the Limit

Metabolic stress is another vital factor in inducing muscular hypertrophy. This principle involves working the muscles to the point of failure or near failure during training. When muscle fibers are pushed to their metabolic limit through repeated actions, it triggers hypertrophic responses. This stress leads to an accumulation of metabolic byproducts, such as lactate and hydrogen ions, within the muscle cells. The buildup of these byproducts creates an environment conducive to muscle growth. To achieve metabolic stress, high-intensity training with challenging loads and higher repetitions is often employed.

Synergy Among the Principles: Achieving Optimal Muscle Growth

While each principle plays a distinct role in muscular hypertrophy, their combined effects create a powerful synergistic impact on muscle growth. Progressive tension overload ensures that the muscles are continually challenged, prompting them to adapt and grow stronger. Muscle damage from intense training sessions serves as the stimulus for repair and growth during rest and recovery periods. Metabolic stress, achieved through pushing the muscles to their limits, contributes to the release of growth-promoting factors and the overall hypertrophic response.

Integrating all three principles into a well-structured training program is key to maximizing muscle growth potential. By progressively increasing weights, focusing on proper exercise form, allowing sufficient recovery time, and incorporating high-intensity sets, individuals can optimize their muscle-building efforts.

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Compound Exercises

If you’re looking to get in shape, this list of compound exercises will help you do so. Compound exercises are effective for building strength because they work multiple muscle groups at once. They also recruit more muscle fibers than isolation exercises do. This means that compound moves build muscle faster and burn more calories over time. Ready to start getting fit? Here are some compound exercises you can add into your workout routine:


Squats are a great exercise for building your legs, butt, and abs. They’re also the most basic compound exercise you can do. If you want to build muscle mass and strength, squats should be at the top of your list of exercises—and there are lots of different squat variations to choose from!

The squat is performed by bending down with your back straight and lowering yourself until your thighs are parallel with the floor or lower, then standing back up again. There are several different types of squats.


The deadlift is a compound exercise that works several muscles in your body. It targets your core, legs, back and grip strength. The deadlift is one of the best full-body workouts you can do to build muscle mass and burn fat.

deadlift variations

The deadlift also helps with other exercises such as squats, lunges and rows. If you want to improve your performance on these types of exercises then adding in some heavy deadlifts will help build up those muscles needed to get better results from those exercises.

If you are new to weightlifting or have never done any kind of workout before then I would suggest starting with lighter weights until you get used to how it feels when using heavier weights in order not hurt yourself by doing too much too soon!

Barbell Overhead Press

  • Start with a barbell in the rack at shoulder height.
  • Unrack into the front rack position
  • Lift the barbell up above your head, keeping it at arms’ length and using only your shoulders to lift it. This is also called a shoulder press or military press.


Pull-ups are a great exercise to include in your workout routine. They can be done using a chair or tree branch, and they work the back, biceps, lats and abs.

squat, bench and deadliftSource: Ketut Subiyanto from Pexels

You can also modify them to make them easier if you are just starting out on pull-ups or you have a specific injury that prevents you from doing the full movement of pulling yourself up with your arms. In general, the more challenging version is better because it will build more muscle mass throughout the upper body area by increasing strength in those muscles over time.

A good way to start developing some basic fitness levels before tackling this challenge is by doing inverted rows on an incline bench at home or at the gym; this will help strengthen core stability as well as arm strength for pull-ups later down the line.

Bench Press

The bench press is one of the most popular exercises among weightlifters. It works the chest, shoulders and triceps.

man trains to get a stronger bench press with spotterSource: Ketut Subiyanto on Pexels

To do the exercise: lie on your back on a flat bench with your feet planted firmly on the floor. Grasp a barbell with your hands slightly wider than shoulder-width apart and lower it toward your chest until it touches (about halfway down). Then push it back up to its original position. You can also use dumbbells for this exercise; just remember that you’ll have to increase or decrease the weight accordingly depending on which version you’re doing (the grip will be different).

These compound exercises will get you in shape quickly.

Compound exercises are the best way to get in shape quickly. They work multiple muscle groups, which helps you build strength faster and increase your muscle mass. As a result, compound exercises are the best way to burn fat and increase your overall fitness level.

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