Unless you have been living under a rock, you have probably heard the latest fitness trend that goes by different names but same meaning such as “lifting lighter weights just as effective as lifting heavier weight” by Huffington Post and “quick tip: build muscle with light weight” by Men’s Fitness. All this stems from McMaster University research led by Dr. Stuart Phillips which as I quote from EurekaAlert!:
Researchers recruited two groups of men for the study–all of them experienced weight lifters–who followed a 12-week, whole-body protocol. One group lifted lighter weights (up to 50 per cent 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 eight to 12 repetitions. Both groups lifted to the point of failure.
Researchers analyzed muscle and blood samples and found gains in muscle mass and muscle fibre size, a key measure of strength, were virtually identical.
If you are interested in reading the full research paper, feel free to read the paper as published on Journal of Applied Physiology on May 6, 2016.
What do Elite Strength and Conditioning Coaches Do
Quite an intriguing conclusion considering this goes against what most world class strength and conditioning coach advises when your goal is to build strength or power. They advise lifting 85% of your 1 RM for a few times, and never push till past the point of exhaustion. Of course this could be different if the goal is fat loss or hypertrophy.
So why such vast difference in training method? Why don’t we look at a research done in 2003 by Eastern Illinois University comparing powerlifters, olympic weightlifters, and bodybuilders. Basically all of the research subjects are of the same weight, height, and thigh muscle mass. But the powerlifters and olympic weightlifters simply outlifts the bodybuilders by a big margin. If, as Dr. Phillips mentioned, “muscle mass and muscle fibre size are key measure of strength”, then shouldn’t they all be equal?
And by the way, Dr. Phillips statement “The other group lifted heavier weights (up to 90 per cent of maximum strength) for eight to 12 repetitions. ” is also funny. If you can do up to 8 – 12 reps in a single set, you are most probably NOT doing 90% of your 1 RM. Elite Russian Olympic weightlifters and elite American powerlifters can only do 2 – 3 reps when they are doing 90% to 100% of their max.
What Causes The Difference
The key here, as Dr. Stuart McGill explained in his book Ultimate Back Fitness and Performance, is that muscle mass and muscle fiber size are not the only keys to measure strength. Another key ingredient is called neural density. Bodybuilders tend to train 8-12 reps per set, at 70% of their 1 RM, emphasizing the “muscle burn”. Olympic weightlifters only do 3-5 reps per set, at 85% of their 1 RM, emphasizing on technique, neural “grooving” and speed to lock out position. Hence the later group ended up with much higher neural density, i.e. the capability of having all their muscle fiber fire up at the same time at high speed. If, you train with even lower weight, at much higher rep (up to 25 on the McMaster research subjects), then you can be sure that your neural density will be even lower than the average bodybuilder’s.
As you already know, our body is great in adapting towards its environment. If you train your body to do low weight, high rep isolated training, then it will be adapt at doing that. And having low neural density means that some muscles will work while others will “cool off” at the same time while you are doing a particular movement, allowing you to have longer endurance.
So at the end of the day, it depends on your goals. If your goal is muscle mass and you don’t care about strength gain, then by and large, the low weight high rep method can also be used and its probably safer than going heavy if you don’t have the movement proficiency to begin with. If your goal is strength gain, then please don’t bother with this latest fitness trend.