HIT. Does it work?
That’s the question posed by one Muscle Evo reader this week.
“I’m currently following a HIT program,” he wrote. “I do one working set to failure and leave a minimum of four days between each workout to encourage maximum growth. What do you think about HIT? Is it an effective way to build muscle?”
HIT is short for high intensity training (not to be confused with HIIT, or high intensity interval training).
It was made popular in the early 1970’s by Arthur Jones, the inventor of the Nautilus range of exercise machines. Most HIT programs revolve around short workouts, a high intensity of effort and a low volume of training, which I’m going to define here as the number of sets per exercise.
“The set should be terminated only when it is impossible to move the weight in any position,” Jones wrote in one of his Nautilus Bulletins. “When the bar literally drops out of your exhausted hands.”
The idea behind doing one set to failure is that as soon as you reach the point of momentary muscular failure, the muscle growth “trigger” has been activated. Once the “growth mechanism” has been set in motion, additional sets are unnecessary as they simply make inroads into your limited recovery ability.
Is HIT an effective way to build muscle?
HIT is actually an umbrella term that covers a wide range of training programs, each one with a number of very different training variables.
Mike Mentzer’s version of HIT, for example, differs from the type of training recommended by Arthur Jones. The routines in Mike’s first Heavy Duty book also differ substantially from those in his second book (Heavy Duty II: Mind and Body).
All of which makes it impossible for me to say that HIT is either effective or not effective. It’s more of a philosophy or set of guiding principles than it is a specific program.
So here, in no particular order, is a random collection of my thoughts on the subject of HIT, training volume, and the importance (or not) of training to failure:
1. The way that training volume is distributed over the course of the week will have a big impact on your progress. Three sets done once a week, for example, is going to produce different results to one set done three times a week.
2. A single set is never really a single set as it will invariably be preceded by several progressively heavier warm-up sets, all of which can contribute to gains in muscular size and strength.
3. There is a theoretical “optimal” number of sets per muscle group, above and below which gains in strength and size will be compromised. This optimal number will depend on your goals, genetics, recovery ability, training age, diet, as well as any other training you’re doing. It will also change over time.
4. The optimal number of sets per exercise also depends on the exercise itself. The deadlift, for example, is an extremely demanding exercise that works more muscle mass than any other movement. Recovering from the deadlift takes longer than it does from exercises such as the bench press or overhead press. This is something you’ll need to factor in when deciding how many sets of the deadlift to do.
5. Stimulating gains in size and strength is not an “on-off” phenomenon. When you want to get a tan, you gradually expose your skin to the sun and your skin gets darker. It’s not necessary to expose your skin to the most intense sunlight it can stand, to the point where it blisters.
6. There’s nothing particularly special about reaching concentric failure, as your muscles are still capable of doing both eccentric and isometric work. Nor is there any good reason to believe that hitting concentric failure (as opposed to eccentric or isometric failure) is what flips the muscle growth switch to the “on” position.
7. The relationship between input (training volume) and output (muscular gains) isn’t a balanced one. Three sets of an exercise may yield better results than one set. But they won’t deliver three times better results. Spending three times longer in the gym is no guarantee that you’re going to gain muscle three times more quickly.
SEE ALSO: THE MUSCLE BUILDING CHEAT SHEET
If you're fed up spending hours in the gym with nothing to show for it, then check out The Muscle Building Cheat Sheet.
It's a "cut the waffle and just tell me what to do” PDF that tells you exactly how to go about building muscle. To download a copy, please click or tap here.
ABOUT CHRISTIAN FINNChristian Finn holds a master's degree with distinction in exercise science, is a former personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Fit Pro, Zest, and Perfect Body magazine.