Mike Mentzer's Heavy Duty Lifting

For the past several months, the Instagram algorithm has been blitzing me with content about legendary bodybuilder Mike Mentzer. 

Maybe it’s because the algorithm has picked up on the fact that I’ve transitioned away from powerlifting and am doing more bodybuilding-type workouts these days. Or perhaps the algorithm thinks I might appreciate Mentzer’s awesome mustache since its majesty rivals my own. 

Whatever the reason, thanks to Instagram, I’ve been learning a lot about Mike Mentzer and his iconoclastic training philosophy that he called “Heavy Duty.” 

The young bros on social media are absolutely bonkers about Heavy Duty. And I can understand why.

First, there’s the appeal of Mike Mentzer himself. He had an amazing physique (he was the first and only man to earn a perfect score in the Mr. Universe competition), and his 1970s hair and stache gave him lots of cool cache. On top of that, he brought a rare philosophical bent to bodybuilding. His tear-drop spectacles evinced his bookish personality, and he loved studying and discussing different schools of thought (particularly Ayn Rand’s Objectivism), looking at art, and listening to good music. For a lot of guys, this combination of brains and brawn really represents the ideal of manhood.

But Mentzer’s Heavy Duty program is getting a lot of hype these days on social media because it promises exceptional muscle growth by potentially only doing a single set of exercises per body part per week. 

Mentzer’s idea that you could get hypertrophic growth with infrequent and short workouts flew in the face of the bodybuilding orthodoxy of the 1970s and 80s. During that time, high volume was king. Bodybuilders back then, like Arnold Schwarzenegger, trained for two hours, twice a day, every day. The goal was to slam your muscles with double-digit sets to stimulate growth. 

Influenced by Nautilus inventor Arthur Jones’ philosophy of high-intensity training, Mentzer thought doing so much training was a waste of time and led to suboptimal results. 

Intrigued by the hoopla and claims of Heavy Duty, I decided to take a deep dive into the program and its claims. Here’s what I found out about how it works, and whether it works. 

The Principles of Heavy Duty

The first thing to point out is that Heavy Duty isn’t a wholly unique training philosophy. It’s a variation of high-intensity training in which athletes are prescribed to train their muscles to failure. As mentioned above, Arthur Jones pioneered high-intensity training. Mentzer probably did the most to popularize high-intensity training thanks to his work with Dorian Yates. 

Mentzer’s Heavy Duty philosophy evolved over the years. Most bodybuilders (and many sports scientists) think Mentzer’s early version of Heavy Duty got a lot of things right. However, Mentzer became more extreme with his views as he got closer to his death, particularly regarding volume and frequency. 

It should be pointed out that Mentzer had genetics that made him well-suited to bodybuilding, and he achieved his physique partly through the use of anabolic steroids. But he thought his recommended lifting regimens equally applied to average, drug-free individuals who wished to achieve their natural muscular potential. 

High Intensity

Intensity is the key to Heavy Duty. For Mentzer, the intensity of the exercise is what drove muscle hypertrophy, not volume. So, what did Mentzer mean by intensity?

He defined it as “the percentage of possible momentary muscular effort being exerted.” 

Mentzer (and other high-intensity training proponents) believed you needed to get reps as close to 100% exertion as possible to stimulate muscle growth. And you only know if you’re getting to 100% exertion by lifting until failure. 

Mentzer on intensity: