Bells Broadcast: True or False… Heavy weights build more muscle than lighter weights?

Hearing that higher repetitions with lighter weights have little effect in muscle mass may have you questioning your fitness routine. In contrast, it’s well-established that heavy weights lead to greater hypertrophy, however, science has proven both WRONG!


Today, Annabel and the teams at Longevity Exercise Physiology Drummoyne, EdgecliffMarrickvilleBella VistaRandwickPymbleBalmainNeutral Bay, Coburg – Melbourne, and Barrie, Ontario – Canada will examine the relationship between lifting heavy verses light weights and muscle mass contribution. We will and delve into the advantages and disadvantages of lifting both light and heavy weights.

Muscle growth does not depend on the amount of weight you lift. It is a myth that one must lift more weight to bulk up. If you’re consistent and patient with lighter weights, you can achieve similar results. It all comes down to two factors: the number of reps, and the way you perform them to achieve muscle fatigue. The goal of your workouts should be to work your muscles to the point of fatigue (i.e., when you can no longer do another repetition) no matter how much weight you are using. So, whether you are doing five dumbbell curls with a 20-kilogram weight, or 20 reps with a 5-kilogram weight, if you are getting to the point of muscle fatigue, you’ll get stronger.

“It all comes down to two factors: the number of reps, and the way you perform them to achieve muscle fatigue.”

A 2016 study called ‘Pumping Iron: Lighter Weights Just as Effective as Heavier Weights to Gain Muscle, Build Strength’ published in the Journal of Applied Physiology compared two groups of experienced lifters over a 12-week period in which one group used lighter weights (up to 50% of maximum strength) for sets ranging from 20 to 25 repetitions. The other group lifted heavier weights (up to 90 per cent of maximum strength) for 8 to 12 repetitions. Both groups lifted to the point of failure. The conclusion, using muscle and blood samples, stated that gains in muscle mass and muscle fibre size were “virtually identical”.

“…one group used lighter weights …the other group lifted heavier weights. The conclusion… stated that gains in muscle mass and muscle fibre size were ‘virtually identical’.”

Another study has shown equivalent hypertrophy with light and heavy weights, from untrained individuals to experienced lifters. Truth is, is that muscle growth is the same when volume is equated for, and sets are taken close to failure.

So, what exactly is the difference between light and heavy weights? Pushing close to failure with higher repetition range is a lot more uncomfortable compared to heavy weights, though it’s best to get close to failure to recruit more muscle fibers no matter the weight. While it is entirely good practice to start with lighter weights and more reps, it may not be a good idea to always stick to the same weights. Over a period, as strength improves, it is important to challenge your muscles to lift more for general progress of your strength.

“As long as you are getting to the point of muscle fatigue, you’ll get stronger.”

A final note – while both can elicit similar results in terms of hypertrophy, heavy weights are more effective for improving strength. Combining heavy weights for compound movements and light weights for isolated movements is the best strategy. When lifting to the point of exhaustion, it doesn’t matter whether the weights are heavy or light.

Have a think about your current strength exercise program, and whether you are achieving the results you would like to. It’s important to remember that there are many factors that go into building muscle mass, apart from the workouts you perform. Diet, genetics, metabolic rate, hormone levels, body type, and even your individual muscle fibre composition all contribute.


A Longevity Exercise Physiologist can help you design a plan to build muscle safely and effectively. We are trained health professionals and can tailor the our sessions to meet your goals!


Give Longevity Exercise Physiology Drummoyne, EdgecliffMarrickvilleBella VistaRandwickPymbleBalmainNeutral Bay, Coburg – Melbourne, and Barrie, Ontario – Canada a call on 1300 964 002 to help you with an exercise program that meets your needs & goals today!


Written by Annabel Bergman



Morton, R. et al. (2016) Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men, Journal of applied physiology (Bethesda, Md. : 1985). U.S. National Library of Medicine. Available at: (Accessed: October 17, 2022).

Livingston, M. (2019) These are the weights you should lift at the gym to get stronger, CNET. CNET. Available at: (Accessed: October 17, 2022).

Building muscle mass: More weight or more reps? (2022) Genesis Health Clubs. Available at:



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