Lighter Weights versus Heavier Weights

Guest post by Enid Fox, BA, ACSM Certified Health Fitness Specialist, ACSM/ACS Certified Cancer Exercise Trainer

In my last FitNet message I stressed the importance of increasing muscle mass to manage weight. Increasing muscle mass matters more than losing fat. You can not lose fat if you are losing muscle.

If you diet without building muscle, or lose weight too fast, the loss of muscle makes substantial weight loss nearly impossible. Cardio exercises are not enough to enhance weight loss or weight maintenance. Consistent resistance training is an essential part of any weight loss or maintenance program. Doing resistance training 3 days a week is optimal and 2 a week is adequate. Which do you think is better, lifting heavy or light weights? The answer may surprise you!

By industry standards, lifting heavy weights is the key to optimizing muscle mass and strength. The goal is to lift at about 85% to 95% of your maximum capacity for at least 3 sets of 10 repetitions. Of course, this type of lifting is challenging and gets you far beyond your comfort zone. When you do the last 3 repetitions of the last set you are close to maximal fatigue. This type of demand on your muscles challenges your tendons, ligaments and bones too. The trouble is, muscle will respond faster than tendons and as you load more and more you risk suffering from tendinitis. For older people, lifting heavy weights increases risk of tendon injury as well as being too demanding.
The good news is, recent research shows that using lighter weights can increase muscle size and strength too! You just have to do many more repetitions. In a recent study, men were performing at 30% to 50% of their maximum capacity for up to 25 repetitions, enough to exhaust the muscles. “The results were unequivocal. There were no significant differences between the two groups. All of the men had gained muscle strength and size, and these gains were almost identical, whether they had lifted heavy or light weights.”

“Interestingly, the scientists found no connection between changes in the men’s hormone levels and their gains in strength and muscle size. All of the men had more testosterone and human growth hormone flowing through their bodies after the workouts. But the degree of those changes in hormone levels did not correlate with their gains in strength.”

“Instead, the key to getting stronger for these men, Dr. Phillips and his colleagues decided, was to grow tired. The volunteers in both groups had to attain almost total muscular fatigue in order to increase their muscles’ size and strength.”

This is good news for people who do not like, or are at risk, doing heavy weights. The key is either way, you need to feel like you cannot do one more repetition when you finish!
You can read more in the New York Times article, Lifting Lighter Weights Can Be Just as Effective as Heavy Ones that was published  July 20, 2016.
Lift Weights and Thrive!
Enid Fox

Enid Fox, BA, ACSM Certified Health Fitness Specialist, ACSM/ACS Certified Cancer Exercise Trainer, is a Personal Trainer at BayClubs Courtside.

She can be reached at

  4 comments for “Lighter Weights versus Heavier Weights

  1. Jim Guerin
    August 29, 2016 at 7:09 am

    Dr Mike,

    Enid’s reference – “Interestingly, the scientists found no connection between changes in the men’s hormone levels and their gains in strength and muscle size.” using lower weight / higher rep. In your experience, how does the lower rep regimen affect QM blood testing parameters other than testosterone?


    • August 29, 2016 at 9:55 am

      Hi Jim,
      From my own hormone panels it is clear that very demanding interval work is a big testosterone booster. I’ve got the data and the big bad, very bad hill that I run to prove it. Buried in the weeds of all this are genetic issues. There is a pretty broad and not precise array of genes that determine whether you will have strength or mass gains from the same workout; that determine whether or not you get a big hormone boost or a little one from the same workout. Most exercise and hormone data is very flawed; they don’t track long enough to see effects on Sex Hormone Binding Protein nor on other intermediate binding proteins nor short term effects of FSH and LH. They just look at total and let it go at that. Be clear: it is a good idea to mix it up. Light weight, high-rep/set schemes with power,short-pyramid work every now and then. All good trainers know that all training is in cycles. The old version of the lightweight idea was called ‘German Volume Training’ and consisted of 10 sets of 10 reps to failure of each exercise. Enough exercises of that makes for a long training session. So Jim, to some extent, you will need to be creative with the primary goal of more flexibility, more power as in rowing/running/stair climbing and a deeper state of calm of mind and heart. Shorter answer to your question: the lover weight rep/set scheme improves insulin sensitivity; a very good thing. Jim, I apologize for the long answer. Dr. Mike

  2. Dan
    September 3, 2016 at 9:15 am

    There’s considerable push-back from the strength-training folks. Apparently the study design was terrible, and the results worthless. If true, that’s unfortunately pretty typical for diet-and-exercise research these days. The conclusions *might* be true, but the study doesn’t prove it, and I’d be surprised if the experiment is replicable.

    Here’s a video of a roundtable discussion:

    • September 3, 2016 at 12:22 pm

      Hi Dan, There is one lurking fact that the study was inadvertently addressing: there are actual genetics to who will respond to low weight/high volume training and who will respond, even in that regard, with mass or strength or both. Short-stack-pyramid schemes work, German Volume Training works, on-and-on. The array of genetic markers for who responds to what is large and interconnected so that no particular genetic pattern is 100% predictive; still genetics is at play. The only really dogmatic people I’ve run into are the power trainers; and I learned a lot from them too. “Measure, modify, and remeasure” is the only sure way: Quantitative Medicine makes sense even for this controversy. It is great to hear from you, Dan. Fire back! Dr. Mike

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