Now I know the standard philosophy has always been “lift heavy or go home,” but that appears to be true only if you’re trying to get appreciably stronger because it’s part of your sport, you’re preparing for the zombie apocalypse, you ‘re woefully insecure, or it helps you in your afterschool job of hoisting sacks of manure onto a truck.
William Kraemer, the Duke Kahanamoku of modern weightlifting theory, stressed in his landmark 2004 paper that using high loads was absolutely necessary so that we could recruit the max number of muscle motor units and thus fully realize a muscle’s growth potential.
Others thought that lifting heavy caused tsunamis of growth hormone and testosterone to be released, both of which would work in concert to nurture muscles. Unfortunately, that’s happy horseshit.
As I’ve stressed innumerable times before, just about anything, even hitting your head with a hammer, releases growth hormone (GH). The key to GH-induced growth is sustained and supranatural increases of the hormones – not a short-lived little duck snort. The same is true of testosterone. While heavy weights might induce a post-workout surge, you need a sustained surge for it to have any growth benefits.
Anyhow, most of us grew up embracing Kraemer’s go heavy or go home dictum, but more recent studies have thrown some shade on that theory. Now I realize that I just finished talking about how studies are prone to confounding factors, but when enough studies come up with the same conclusions, you think maybe that the nerds are onto something.
Specifically, new studies show that training to failure or near failure is more important to muscle growth (not strength) than using heavy weights. Doing as many reps as you can, even with light resistance, ends up recruiting just as many or nearly as many motor units as lifting heavy does, so “lift heavy or go home” no longer has to be the rule of the realm.
Instead, there’s no need to go home – just train to failure and maybe hang around later for a nice mango and whey shake.
Schoenfeld and his colleagues found that doing 25 to 35 reps to failure (which requires muy light weights) worked as well as doing 8 to 12 reps to failure… except in the biceps, where high rep training worked better, increasing the biceps size of participants by 8.6% compared to the 5.3% realized by those who performed low(er) rep/heavier weight training.
Another study, this one conducted by Robert Morton and his colleagues (2016), found that doing high reps (20-25) with light weights (again to failure) worked as well as doing 8-12 reps to failure. Their theory? Volume (reps times weight) can be as important as intensity (percentage of 1RM).
These higher rep ranges usually corresponded to lifting weights that represented 30 to 50% of subjects’ 1RM while the lower reps corresponded to lifting weights that ranges from 75 to 90% of 1RM.
And, if you want to throw another study into the pile, Kumar and his colleagues experimented with exercise intensities of 20, 40, 60, 75, and 90% and found that 60% of 1RM was the magic number, stimulating protein synthesis to a greater degrees than any other percentage.
But figuring out percentages requires that you first determine your 1RM on every single goddam lift and then doing some cipherin’ to figure out how much weight to use. And hardly anyone is going to go to all that trouble.
My recommendation, at least to anyone with a few months/years of lifting experience, is to pick a higher rep range and use your instincts to pick the corresponding weight. It may take you one or two sets to get it right, but it’s quicker than figuring out your 1RM’s on all your lifts.