Study on Lifting Lighter Weights: What It Means

DB-bench-pressResults of a new study (Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men) were released recently leading to plenty of media coverage with headlines like these:

  • Lifting Lighter Weights Can Be Just as Effective as Heavy Ones

  • Lifting Lighter Weights Is Just As Effective As Heavy Weights

  • Lighter weights just as effective as heavier weights to gain muscle, build strength

  • New Study Finds Lifting Lighter Weights as Beneficial
  • New McMaster study says you can lift small and get big

It's nice to have strength training in the news, and most of the coverage hits the highlights, but it also tends to be rather misleading. Let's take a closer look.

How "New" Is This Conclusion?

While the results from this study are indeed recent (published 1 July 2016), it builds on previous studies dating back to 2010 that reached the same conclusion. What's new about this study is the background of the participants: unlike most previous studies, this one used people (young males) who had resistance training experience. The goal was to see if results from previous studies might only apply to untrained people who were more susceptible to muscle adaptations in response to lifting weights. So this study provides new evidence rather than a new conclusion. That's not always clear from the coverage, and especially from the headlines.

How Light is "Light"?

Perhaps the most misleading part of many of the articles covering this study is the image used: too often, it's one with a tiny, colorful dumbbell like this:

woman with 1-pound dumbbells

Yes, those are one-pound dumbbells.

The unfortunate implication of such images is that these things are all you need to build muscle and strength roughly equivalent to lifting heavy weights.

In weightlifting, the term "one-rep max" (1RM) is used to indicate the heaviest weight that a person can lift one time for a particular exercise. For example, if a person can bench press (lower the bar to the chest and press it back up) one hundred pounds no more than one time, that person's 1RM for the bench press is 100 pounds.

bench press

Bench press (not great form)

A weightlifting program may use percentages of the 1RM. For example, it might specify using 70% of the 1RM for 8 reps. (In our example, that would mean bench pressing 70 pounds 8 times.) In the study, the "low rep" (LR) group used 70-90% of their 1RM for 8-12 reps. The "high rep" (HR) group--that is, the group using the light weights--used 30-50% of their 1RM for 20-25 reps. That's not going to be a tiny, brightly-colored dumbbell for any reasonably healthy person. (Yes, there are "isolation" exercises that could be exceptions but they certainly weren't used in this study.)

Who Were The Study Subjects?

According to the study, the participants were "Forty-nine healthy young men (23 ± 1 yr, 86 ± 2 kg, 181 ± 1 cm, means ± SE) who had been engaging in RT for at least the past 2 yr [4 ± 2 yr, training >2 sessions per week (range 3–6 days/wk)..." In other words, they were fit young guys. (56 started but 7 of them didn't complete the study for various reasons.) As mentioned earlier, previous studies have used untrained people but they were also young. There has been at least one similar study using less-young participants (Strength training at high versus low external resistance in older adults: effects on muscle volume, muscle strength, and force-velocity characteristics) with similar results. Again, this isn't "news."

How Hard Did They Work?

This is the key point and easy to miss with all the talk of "lighter weights" (and pictures of tiny, colorful dumbbells). Both groups did three sets of each exercise with each set going to "volitional failure." This means they kept going until they didn't think they could do another rep. In other words, both groups worked hard! With lighter weights, it took longer to get to failure (20-25 reps or so) compared to the heavier weights (8-12 reps or so).

In the study conclusion, the authors write, "We speculate that because the participants in the HR group performed greater volume, they were able to exercise until volitional failure, which allowed for maximal activation of their motor units..." In other words, both groups lifted the weight as many times as they could, but with the lower-weight/higher-rep group, it took more reps to get there.

In an earlier post, I wrote about an "Easy Strength" program I did that used low reps (generally from 2-5) and got more volume by lifting more often (five days a week)...without even going to "volitional failure." I'm not aware of any scientific experiments for this type of training, but far more than 49 people have done it successfully (that is, to gain strength). There are plenty of ways to work out hard that apparently yield good results. Alas, setting up rigorous scientific experiments is difficult (and expensive).

How Similar Were The Results?

The study workouts included the following resistance exercises:

  • Inclined leg press
  • Seated row
  • Barbell bench press
  • Cable hamstring curl
  • Front planks
  • Machine-guided shoulder press
  • Bicep curls
  • Triceps extension
  • Wide-grip pull downs
  • Machine-guided knee extension

The 1RM tests were done only on the leg press, bench press, shoulder press, and knee extension.

Of these, the only exercise to show statistically significant differences between the low-rep and high-rep groups was the bench press where the low-rep group (with heavier weights) had better results. Is it just a coincidence that this was also the only exercise tested that used free weights (barbell) instead of machines? Maybe. But I'd be interested to see differences in other free weight exercises, in particular squats, deadlifts, and overhead presses.

Anything Else?

I'd still like to see a real-world example of this in action; e.g., a successful bodybuilder using only high reps and lighter weights. Maybe it will happen eventually, but it will be hard to get competitors to try a program like this that works in the lab rather than one that has been shown to work for thousands of people over decades in actual competitions.

Another variable I'd like to see measured is rest between sets. For this study, both groups rested one minute between sets. Typically, heavier lifting uses longer rest periods (often 3-5 minutes). But more variables makes for difficult experiments so it's understandable why the rest times were kept the same. Nonetheless, it would be interesting to vary both loads and rest periods and see the results of different combinations.

In any case, if people want to use lighter weights (but not too light!) and higher reps, that's fine with me. We had a guest post here about training with higher reps not too long ago. It's also fine to mix things up, using lighter weights for some workouts and heavier for others. Indeed, that's a regular part of developing strength training programs for people.


Bottom line: lift weights, work hard, get stronger. Everyone can agree on that, right?

Be seeing you.




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