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Do you need to lift heavy to build muscle?

In the quest for muscle hypertrophy, or muscle growth, athletes and fitness enthusiasts often find themselves asking: do I need to lift heavy to build muscle?

This question, central to the design of effective resistance training (RT) programs, has sparked much debate and research in the sports science community. The pursuit of hypertrophy is not just a matter of aesthetics for bodybuilders or athletes but a crucial aspect of improving performance and injury prevention across various sports.

This blog post dives into the relationship between lifting weights, muscle hypertrophy, and strength gains, guided by recent research and practical implications for fitness training strategies.

A man hearing a hat backwards performs a barbell bicep curl.

The relationship between muscle size and strength

The traditional view holds that larger muscles are stronger because they contain more sarcomeres, the fundamental muscle units, arranged in parallel, which should theoretically produce more force.

This principle has been the foundation of hypertrophy-oriented resistance training in sports for years. However, the straightforward equation of "bigger muscle equals stronger muscle" has been challenged.

In 2016, Buckner and colleagues (1) critically examined this relationship, presenting the following arguments:

  • Hypertrophy is not necessary for strength gains as strength can increase without an increase in muscle size.

  • Hypertrophy is not sufficient for strength gains as muscle size can increase without a corresponding increase in strength.

  • Hypertrophy does not directly contribute to strength gains, indicating that muscle size increase is neither necessary nor sufficient for enhancing strength.

These points have ignited a reevaluation of how hypertrophy and strength gains are approached, suggesting a more complex interplay than previously understood.

Load/intensity parameters for strength training

A personal trainer watches as his client flips and pushes a tire while on turf inside a gym.

The concept of a "hypertrophy zone," typically defined as training within a 6- to 12-repetition maximum (RM) range, has long been accepted as the optimal approach for maximizing muscle growth (2,3).

This belief is based on the premise that such a range strikes a balance between intensity, or the amount of weight lifted, and volume, the total amount of work done, ultimately creating the ideal conditions for muscle growth.

Competitive bodybuilders, known for their significant muscle development, often train within this range. However, recent research questions the existence of a specific hypertrophy loading zone, pointing to the efficacy of a broader spectrum of loading ranges for inducing muscle growth.

The importance of effort and training across loading zones

Research indicates that muscle protein synthesis (MPS), a key driver of muscle hypertrophy, may not be significantly affected by the magnitude of load as long as the training involves high effort levels. This suggests that lifting heavier weights is not the only path to muscle growth.

A man uses a bench while in a gym to perform a heavy repetition of barbell bench press.

Studies have shown similar hypertrophic outcomes across a wide range of loading intensities, from low to high, as long as sets are taken close to muscle failure. A meta-analysis by Schoenfeld and colleagues found no significant difference in hypertrophy between high-load, or >60% 1RM, and low-load, or <60% 1RM, training modalities, as long as the sets were performed to muscle failure (4).

This revelation reinforces the premise that the exertion level, rather than the amount of weight lifted, plays a crucial role in stimulating muscle growth. This has practical implications for training design, suggesting that incorporating a variety of repetition ranges can potentially enhance muscle development more effectively than sticking strictly to a moderate loading zone.

Practical recommendations for hypertrophy training

Given the evidence, a practical approach to hypertrophy training might include:

  • Utilizing a variety of loading (weight) zones, from low to high, to target muscle growth effectively.

  • Starting hypertrophy-focused training cycles with a short block of heavy, strength-oriented training to potentiate the use of heavier loads in later phases.

  • Being mindful of the discomfort and higher perceived effort associated with training at very low loads, which may not be as time-efficient or comfortable as moderate loads.

  • Recognizing that high loads increase body stress, thus demanding careful planning and experience in executing the specific exercise correctly.

  • Considering the individual differences in response to moderate loads, which can be influenced by genetics, training modality, body area trained, and exercise type.

Simplified training guide

The chart below presents training principles through a sample 2-week progression sequence for a back squat exercise.

Week 1

Day 1

Day 3

Day 5

Intensity (load lifted; %1RM)




Repetition Range

10-12 reps

15-20 reps

12, 10, 8, 8 reps





Effort (RPE)

Moderate (6-7)

Near failure (9+)

Increasing (6-8)


Focus on form

Enhance endurance

Push closer to failure on the last set

Week 2

Day 1

Day 3

Day 5

Intensity (load lifted; %1RM)


70% → 85%


Repetition Range

6-8 reps

8 → 6 reps

12-15 reps





Effort (RPE)

Near failure (9+)

Increasing (6-8)

Moderate (6-7)


Challenge strength

Pyramid scheme, increase load each set

Recovery focus, maintain form

This chart is a simplified guide for progression, emphasizing the importance of adapting the program based on individual performance, recovery, and progression over time. It's important to consult a fitness professional prior to following a new exercise program to ensure it's right for you.

Key training principles noted

Progressive overload

Week 2 sees an increase in intensity through added weight and decreased repetitions, ensuring the principle of progressive overload is met.

Effort and intensity

Observe that each day has a different intensity range. Also, consider how the intensity is spread out throughout the program.

A man in athleisure holds two dumbbells as he performs a split squat while in a gym.

Ideally, your training program should be structured in such a way that high-intensity workouts are followed by less-intense workouts.

Advanced considerations: failure training and periodization

As lifters gain experience, the intensity of effort, including training closer to failure, may become increasingly important for continued muscle gains.

For highly trained individuals, such as competitive bodybuilders, taking some sets to momentary muscular failure could be beneficial but should be done conservatively (5).

Moreover, strategies like periodization, which is a method of varying the training focus over time through different loading zones or training models, can help prevent stagnation and optimize muscle growth over the long term.

Putting it into action

The question of whether you need to lift heavy to build muscle finds its answer in the understanding that muscle hypertrophy can be achieved across a wide spectrum of loading zones, provided the training is executed with sufficient effort and intensity.

The key to effective hypertrophy training lies in the strategic variation of loading ranges and incorporating principles of periodization to ensure continuous progress and prevent overtraining.


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  1. Buckner, S. L., Dankel, S. J., Mattocks, K. T., Jessee, M. B., Grant Mouser, J., & Loenneke, J. P. (2017). Muscle size and strength: another study not designed to answer the question. European journal of applied physiology117(6), 1273–1274.

  2. American College of Sports Medicine. (2009). American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Medicine and science in sports and exercise41(3), 687-708.

  3. Kraemer, W. J., & Ratamess, N. A. (2004). Fundamentals of resistance training: progression and exercise prescription. Medicine & science in sports & exercise36(4), 674-688.

  4. Schoenfeld, B. J., Grgic, J., Ogborn, D., & Krieger, J. W. (2017). Strength and hypertrophy adaptations between low-vs. high-load resistance training: a systematic review and meta-analysis. The Journal of Strength & Conditioning Research31(12), 3508-3523.

  5. Schoenfeld, B., Fisher, J., Grgic, J., Haun, C., Helms, E., Phillips, S., ... & Vigotsky, A. (2021). Resistance training recommendations to maximize muscle hypertrophy in an athletic population: Position stand of the IUSCA. International Journal of Strength and Conditioning1(1).


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