Considering the ignorance of the majority of the fitness industry it should come as no surprise most people writing about high intensity training (HIT) on the internet don’t know what they’re talking about. Almost every week I receive emails from people confused by something they read about HIT on some other site, often variations on the same common misconceptions.
The purpose of this article is to clarify what HIT is and what it is not and address some of the more popular myths and misconceptions.
What is High Intensity Training?
Part of the problem is the term “high intensity training” is currently used very loosely by most of the fitness industry to refer to almost any physical activity performed with a higher than normal level of effort. It has also become popular to market all sorts of things as HIT, from group classes to boot camps to CrossFit to sprint interval training workouts, adding to the confusion.
To be clear, when I write about HIT I specifically mean progressive resistance exercise performed with a very high level of intensity.
The Definition of Exercise “Intensity”
Unfortunately, there is even confusion about this due to misunderstanding of the definition of “intensity”. The most accurate and conceptually useful definition of intensity in the context of exercise is your level of effort relative to your momentary ability. The erroneous but popular definition is the load used during an exercise, usually expressed as a percentage of the maximum that can be lifted for one repetition (1RM). There are several problems with this.
For example, according to the proper definition if you are capable of producing 100 pounds of force at the start of an exercise but you only have to produce 75 pounds to overcome the resistance your starting level of intensity is 75% (75 = 75% of 100). As your muscles fatigue, continuing to produce 75 pounds of force requires an increasing percentage of your decreasing momentary ability (75 = ~79% of 95, ~83% of 90, ~88% of 85, etc.). When fatigue has reduced the amount of force you are momentarily capable of producing to 75 pounds then you are working at maximum intensity (75 = 100% of 75).
According to the more common definition (a percentage of 1RM in this case), despite the obvious fact an exercise becomes harder (more intense) as your muscles fatigue, you would be working at the same intensity at the end as you did at the beginning. Whether you quit after only one or two repetitions or performed five or six or continued the exercise to the point of momentary muscular failure, you would be working at the same intensity. Whether you performed each repetition in strict form maintaining continuous tension on the working muscles or cheated the weight up and dropped it then rested between each rep, you would be working at the same intensity. I could go on and on but by now you should get the point; the common definition is plainly wrong. A percentage of a repetition maximum is a description of the load used for an exercise and not intensity.
Load Versus Effort?
Which leads to one of the common misconceptions: just because a program involves using high percentages of your 1RM doesn’t mean it is HIT. While load is obviously an important factor in how intense an exercise is, as I already pointed out it is not as important as how you use it.
For example, doing a set of an exercise with 80% of your 1RM might be hard, but if you do it with loose form and quick reps and stop short of an all-out effort you are not training as intensely as if you used only 75% but pushed yourself to momentary muscular failure.
Please note I am using these percentages for the sake of example and do not recommend performing one rep max testing to determine training loads.
Is HIT Dangerous?
A related misconception is that training very intensely is dangerous. Often this is claimed because of two erroneous assumptions; that intense training always involves very heavy weight and that a heavier weight is more dangerous. Once again what really matters is how you use it.
A tissue is injured when it is exposed to a force that exceeds it’s structural strength. Force is the product of mass and acceleration. The heavier the load you use or the more rapidly you accelerate it the greater the force imposed on the involved tissues. Assuming you don’t have any pre-existing injuries you won’t be capable of lifting a weight that is too heavy if you attempt to do so with strict, correct form. The reason heavy weight is often associated with injury is because people often use sloppy form to be able to lift way more weight than they can handle lifting correctly. It is not the weight that hurts them but the horrible form they resort to in an attempt to lift it.
Suppose you were to go outside and attempt to lift the back of an SUV or pickup truck by the bumper. Unless you are a freak of nature you will not be able to get the wheels off the ground. It is much heavier than anything you are ever likely to try to lift during a workout. Whether you are injured attempting to lift it has nothing to do with how heavy it is and everything to do with how you try to lift it. If you attempt to quickly yank or jerk the bumper up as hard and fast as you can you are probably going to pull something. However, if you pull with only a moderate effort at first, and gradually increase your effort until you are pulling as hard as you can then gradually ease off you will not injure yourself.
If you start with a weight you can handle for a reasonable number of reps in strict form and progress gradually the weight will not become dangerous. If you sacrifice form to lift a heavier weight don’t blame the weight if you get injured.
Is Training To Failure Dangerous?
As long as you use strict form and common sense with regards to safety it is not dangerous to train to momentary muscular failure either. Again, the problem is not training to failure in and of itself, but that as people approach failure they tend to lose focus and sacrifice form for the sake of completing more repetitions. Maintain strict form, focus on your muscles not the numbers, and no matter now intensely you train you will not hurt yourself. In fact, as long as your form is strict the closer you get to momentary muscular failure the safer the exercise becomes because fatigue increases the gap between the amount of force the working muscles can produce and the amount required to cause an injury.
If an exercise requires a spotter or specific equipment to safely train to failure use it. Make sure all equipment you use is in good working condition and that anything you stand on, sit on, lay on or hang from will support your weight. Familiarize yourself with the correct operation of equipment before using it with a challenging weight.
When a trainer says high intensity training or training to momentary muscular failure is dangerous that tells me they don’t understand the actual causes of injury during exercise and how to minimize them and have no business training people or giving advice on the subject.
Is HIT Only For Beginners Or Not For Beginners?
“HIT isn’t very hard. Anybody who only works out for less than half an hour is lazy.”
“HIT is too hard and will totally burn out your CNS and wreck your joints.”
“HIT doesn’t work, you have to do a lot more volume to grow.”
“HIT can be an effective way to stimulate new growth if you’ve hit a plateau.”
“HIT is only for beginners, you have to add more volume as you progress.”
“HIT is not for beginners, you have to build up to that kind of intensity.”
The “experts” can’t seem to make up their minds. Some claim HIT is not for beginners because it is too hard while others claim HIT is only appropriate for beginners because it isn’t hard enough. None of them know what they’re talking about.
There is no reason a beginner can’t or shouldn’t perform high intensity training as long as they start with conservative loads and rest periods and progress gradually while focusing on learning and practicing correct form. The goal is to work up to the point where you’re working out with an all-out, maximum effort but you don’t put someone who has never trained before through that kind of workout without a break-in period.
Also, there is no reason to increase workout volume as you become more advanced. The effectiveness of your workouts is determined by how intensely you train, not the volume of work you perform, and as you become more advanced and are capable of training more intensely it becomes necessary to reduce the volume and frequency of your workouts to avoid overtraining.
Is HIT Only For Lazy People Or Only For Obsessed, Amphetamine-Fueled Masochists?
The notion that HIT is not very hard or is only for people too lazy to work out longer or more often is utterly absurd to anyone who has experienced a proper high intensity workout. Anyone who says a HIT workout isn’t hard has never done one and doesn’t know what they’re talking about.
While in college I worked as a trainer at a Gold’s Gym in Green Bay, WI (now Titletown Fitness) and several of the bodybuilders who worked out there were critical of our HIT program, often expressing doubt that such brief workouts could possibly be very hard. The few I convinced to let me put them through a workout changed their minds. During one of those workouts the guy only got through four exercises before having to go lay down in the locker room. He came out over an hour later and sat down in the front lobby and called his girlfriend to come pick him up since he didn’t think he’d be able to drive. I didn’t see him in the gym for about two weeks and when he came back he complained the workout was too hard.
Since then I’ve trained quite a few people who know what hard work is, including professional athletes and special warfare operators, and none of them thought their workouts were easy.
While HIT is extremely hard when done correctly you don’t have to be obsessed, a masochist, or hopped up on amphetamines to train with a high level of intensity. You just have to be willing to work as hard as possible and disciplined enough to push yourself through the discomfort no matter how much your muscles burn and heart pounds or how hard you’re sucking wind. As I mentioned earlier, intensity is your level of effort relative to your momentary ability. What is “high” intensity is relative to the individual. While not everybody can lift heavy weights, everybody can train with a level of effort that is high for them.