“Does Tribulus Work”; does it raise testosterone or improve muscle growth?
“Is Carnivor Protein Good”; will it build muscle better than other proteins?

“Build Muscle with Light Weights?” First… always pay attention to detail

Can we “build muscle with light weights?”

This is the question that many people seem to assume they’ve found a definitive answer to in the past month. That’s because it was in April 2012 that the Journal of Applied Physiology published findings of a study that basically claims we can. The study showed that a ten-week comparison between lifting heavy weights for low repetitions and lifting light weights for high repetitions produced no difference in muscle mass gains. And ever since the fitness media discovered so much as the abstract to this study, they’ve fallen all over themselves to report it.

Light_Barbell_SquatsWhether this effusiveness of reporting is because the idea that we can ‘build muscle with light weights’ is “good for older people” – or that it’s just fun to ‘stick it’ to those muscle heads who insist on ‘mindlessly’ grunting with and slamming those heavy weights at the gym – is anyone’s guess. I just find it funny that many will unquestioningly take the results of any study that fits a template they favor and make uncritical generalizations based on findings of rather limited research.

I can hear it now: “What are you saying, Scott… that we can’t ‘build muscle with light weights?’”

Of course not; if I’m critical of a generalization made by this study’s findings, I’d be amiss in making my own generalizations in the other direction. I just think the study and accompanying question ‘can we “build muscle with light weights”’ deserve a bit more detailed analysis.

‘Build Muscle with Light Weight’: The research study

Let’s look at the basic structure of the study that’s become the conclusive evidence for so many that we can ‘build muscle with light weights.’

The experiment was done on eighteen healthy young men at McMaster University, Hamilton, Ontario, Canada. The subjects were all around 21 years of age (21 ± 0.8 years). The group averaged 1.76 meters in height (± 0.04 m) and 73.3 kg. in weight (± 1.4 kg.). The subjects were “recreationally active”, but had no formal weight lifting experience or regular weight-lifting activity over the year prior to the experiment.

The 10-week study was done using a unilateral protocol of weighted leg extensions. This means that each of the men’s legs was worked separately on a leg extension machine (“single-leg” leg extensions). The subjects were randomly assigned, in “counterbalance fashion”, to one of the three possible unilateral training conditions for each leg. The following were the three different conditions of weight volumes/set protocols that were performed three times per week for the 10-week period (1RM = single-repetition maximum):

  1. 80% of 1RM (1 set)
  2. 80% of 1RM (3 sets)
  3. 30% of 1RM (3 sets)

The researchers were performing this study as further investigation into their earlier findings that showed greater acute protein synthesis activity in muscles worked at higher volumes with lower loads than at lower volumes with higher loads. The abstract for that earlier study can be found right here. In that experiment, the only factor being measured was post-exercise protein synthesis; not measurements of muscle hypertrophy. But the findings of the study showed that training to failure with 30% of 1RM resulted in more post-workout protein synthesis, for a longer period, than did training with 90% of 1RM. This finding seemed worthy of further testing to determine if hypertrophy (muscle size) is affected. Thus, this latest study was more in direct alignment with determining if we can ‘build muscle with light weight’ as effectively (or more) as we can with heavier loads.

Before and after the 10-week study, the men’s leg muscles were measured using MRI (magnetic resonance imaging). In addition, muscle tissue biopsies were taken before the training began, after the first training session, and again at the end of the ten weeks. These muscle tissue samples were quantified using ATPase histochemistry and Western blotting analysis.

The performance strength of the men’s leg extension capabilities was also measured. Both before and after the training program, the researchers recorded the subject’s 1RM, maximal voluntary isometric contraction (MVC), rate of isometric force development (RFD), and ‘peak power’ output.

So what were the findings; is “building muscle with light weights” a go… or a no-go?

‘Build Muscle with Light Weights’: The study results

In essence, what did the researchers discover in the ‘build muscle with light weights’ versus heavy weights study?

In both thigh measurements and muscle biopsies, there was no statistical difference in hypertrophy between the muscles that were worked for three sets at 80% of 1RM and those worked for three sets at 30% of 1RM. However, there was a more than double degree of average muscle volume increase between each of those respective workout loads compared to the group of 80% of 1RM done for a single set. This suggests that training volume – at least in terms of ‘multiple sets’ versus a single set – might produce more muscle size.


Quadricepts Volume
'Build Muscle with Light Weights': At least in the short term, the study showed that workout volume might be more important than using heavier weights


Another major finding of the study was in the context of max strength gain. ‘Voluntary isotonic strength gains’ were significantly greater in the 80%-1 and 80%-3 groups than they were in the 30%-3 group. This was not so surprising to the researchers since it corroborates findings of earlier studies.

The study also bolstered earlier findings showing a possible connection between acute post-workout muscle protein synthesis and short-term muscle size gains. There was discernibly more protein synthesis activity among the two groups of muscles that were worked for three sets versus the 80% of 1RM worked for one set. Since those two groups obtained over double the muscle size of the single-set group, the connection between degree and longevity of post-workout protein synthesis activity and muscle volume increases seems clear.

What’s not so clear, in my opinion, is whether this means we can ‘build muscle with light weights’ beyond a relatively tiny 10-week period of time.

‘Build Muscle with Light Weights’: Only two ways to continue ‘overload’

Personally, I think this study’s findings are compelling, but hardly conclusive. The most glaring drawbacks are both its short duration and the inexperience of the subjects involved. Many experienced bodybuilders will regularly comment on the anecdotal observation that “rank beginners make progress on ANY workout routine.” Thus, one has to wonder whether the sameness in outcomes between workout weight-loads used in the study would remain beyond ten weeks, or even exist among just slightly more experienced bodybuilders.

During the study, subjects pushed their repetitions to the maximum and, apparently, increased workload only through increases in these repetitions. Obviously, there are only two methods of increasing volume workload on a muscle – by augmenting the workout weight or upping the repetitions performed with the current weight. If continued hypertrophy were desired beyond the 10-week study, an increase in resistance would eventually be required for all three weight-load groups. This raises a pertinent question:

Would there be a greater long-term capacity for resistance increases in either of the two 80% workload groups over the 30% workload groups?

If so, then I’d say that the “build muscle with light weights” rah-rah by the fitness media was premature.

If not… well, then “Yay-hey” for ‘building muscle with light weights’ – especially given its implications for reducing the risk of injury. But I’ll at least bet, based on experience, that even if this is the case, there’s probably a sweet spot somewhere between the 30% and 80% of 1RM loads that were used in the study.

Your opinions are encouraged and welcomed in the comment section.



I think you right there Scott it is finding the balance between the optimum weight and the rep and set scheme being used. Everyone is different and has different strength and muscle endurance levels.


Wouldn't a more conclusive study be done with a variety of subjects, regarding age, sex and weightlifting experience, along with a greater variety of muscle groups being exercised? And, a longer period of training? And, measuring actual muscle mass growth?

Scott Abbett

Hi Ian,

Thank you for reading and providing some thoughtful comments.

I like the resourcefulness of the milk carton idea. Never tried that one myself.

Really good point in regard to injury situations. It seems reasonable to extrapolate from this study result that we can retain our heavy volume workout capability - at least to some extent - by substituting with lighter weights and higher reps schemes.

That scenario might be worthy of a study itself.

I do remain suspended from making conclusions on any of this, however, because of the relative short duration of this study that was done on such rank beginners.


Scott Abbett

Hello Dai,

Thank you for your input.

Interesting point about Surge Nubret. That's an awesome physique from the past. I recently saw 'Pumping Iron' again after not seeing it for... oh, about twenty years? His physique would put a lot of competitive guys of today to shame.

Great point about the higher reps. However, I still think what's under-emphasized in this study and subsequent discussion is the need for a constant increasing of the workout weight volume, regardless of the relative weight/reps scheme employed.



What I get out of this study is that if I am in a hotel room without any weights I can fill up a couple of gallon milk containers and do my usual dumbell routine. It may not be quite as good as lifting the heavy weights but it is more useful than doing nothing. It is also good to know that in the case of an injury it is possible to lift light weights while recovering and not get too far behind.


there’s probably a sweet spot somewhere between the 30% and 80% of 1RM loads that were used in the study.

You are absolutely right on this. Way back when Vince Gironda used the 10 x 10 or 8 x 8 and Surge Nubret used many sets with lighter weights.

I know Cleveland Thomas a natural body builder uses a reverse pyramid using high reps(https://www.muscleandstrength.com/articles/high-rep-blitz-interview-with-bodybuilder-cleveland-thomas.html). So yes there is an argument for lighter weights and higher reps. Exactly what the equation is not sure, I think it would be a trial and error things based on the individual.

The comments to this entry are closed.