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The Case for HIT (High Intensity Training) for Efficient Muscle Growth

For many years now there's been a big debate on which works best for muscle growth - volume training or HIT (high intensity training). Its an area I find especially interesting. In this article I'm going to look a little at both systems and then explain why I feel that HIT is a superior system (with the caveat that its a superior system 'when done properly').

So first off, lets differentiate between the two systems:

Volume Training
- Multiple Sets per Exercise (Often 3-5)
- Multiple Exercises per Body Part (Often 3-4)
- Usually done in 'split workouts' (e.g. Legs/Shoulders on Monday, Back/Biceps Wednesday, Chest/Triceps Friday)
- Typically 30-40 sets per workout
- Typically 60-90 minute workouts
- Usually 3-4 workouts per week
- Rarely any focus on reptition speed and intensity

Hight Intensity Training (HIT)
- Few Sets per Exercise (Often only 1!)
- Few Exercises per Body Part (Usually 1-2)
- In most classical HIT workouts, the whole body is trianed in one workout (no training split)
- Anything from 4-12 sets per workout
- Typically 20-40 minute workouts
- Anything from 3 workouts per week down to as low as once every nine days
- Heavy focus on repetition speed and intensity (all out effort)

So there's quite a clear cut distinction between the two methodologies. It gets murky when you get deeper into HIT because there's a lot of variations from the original HIT pioneered by Arthur Jones. But broken down simply, volume training is many sets and excercises per bodypart and HIT is few.

Before moving onto my argument for HIT, I need to highlight the following points:

1) At least 90% of people who lift weights to build muscle fall under the category of using volume training not HIT.

2) Volume training, in my opinion, works best for most people purely because most people struggle to properly apply the principles of HIT.

3) Most people who have tried HIT, have not done it properly as originally devised by Arthur Jones. They either do too much, too little, or more often they dont perform the reptitions as strictly as intended.

4) Many people shy away from HIT because they believe the system means they need to use very heavy weight (compared to volume training) in order to acheive the intensity, and therefore it carries a higher risk of injury.

5) My argument for HIT is based purely on building muscle. If the goal is improving athletic performance, increasing explosiveness or other more sports related training goals then HIT is often not the best training method.

The Classic Volume vs HIT Comparison - Marathan Runners and Sprinters

Whenever HIT vs volume training is dicussed, almost always the analogy comes up of comparing HIT with sprinting and volume training with marathon running. Whilst volume training workouts are not quite marathon running (in that its still an anaerobic workout, its not even close to an endurance/aerobic event), the comparison is useful. Sprinters train their muscles to work for a very short time, with maximum intensity. World class sprinters can run the 100m in less than 10 seconds, and in order to do so their fast twitch muscle fibres have usually grown to an impressive size. Some sprinters even look almost like bodybuilders. In contrast, Marathon runners are often carrying very little muscle tissue. They train their muscles to work at low intensity for a very long period of time. Now there's other factors that come into play here. Do sprinters get musclular because they sprint, or do they sprint because they have genetically superior allocations of fast twitch muscle fibres? Would someone very muscular ever take up marathon running? A certain amount of the sprinter/marathon runner comparison has to be attributed to genetics amongst other things. However, even with this taken into account, it makes a compelling case for short, intense exercise being superior to lower intensity exercise. The third type of athlete I like to bring into the argument at this point is gymnasts, but we'll cover that later.

Train Long or Train Intense? Can You Do Both?

So our sprinter trains short and intense and has big muscles, our marathon runner trains long and with much less intensity and has relatively little muscle tissue. What if our sprinter trained intense but for much longer? Would he get even bigger? A more appropriate question is 'could' he train so intensely for a longer period? And the answer is no. The world record at 100m is 9.58 seconds. The world record at 400m is 43.18 (10.79 seconds per 100m). If Usain Bolt could run as fast for 400m as he could for 100m then he would be able to do the 400m in under 38.32 seconds (less in fact, as he'd only have to start from a standstill once, not each 100m). Extrapolate that to 800m, or 1500m - he'd smash every track record by some way. But the truth is nobody, not even Usain Bolt, can run at their maximum speed for a long period of time. Back to lifting weights - you can either train at maximum intensity for a very brief time (e.g. like the 100m) or you can train at a proportionately lower intensity for a longer time. The longer you train, the lower your intensity. So you can train much harder on one all out set of barbell curls, than you could doing say 5 sets of barbell curls, followed by 5 sets of dumbbell curls. You're going to hit a much higher peak of intensity in that one all our maximum effort set, than doing 10 sets of barbell/dumbbell curls. Lets say you could train at maximum intensity for many sets. Lets say instead of doing 1 all out effort set of curls, that you could do all 10 sets at maximum effort. Should you then do the ten instead of one?

Tan or Burn - Getting the Right Adaptive Response from the Body

This is another popular analogy HIT-ers like to talk about. If I went on holiday somewhere really hot and exposed my pasty white English skin to the burning sun on my first day for the whole afternoon with no sun cream, chances are by the end of the day I'd be very uncomfortable, lobster red, too sore to move. If instead, I spend 30 mins in the sun on the first day and repeat that for several days, whilst I might not be making the most of the weather chances are I'd find that I don't burn but that I would gradually tan and can stand longer periods in the sun due to the tanning process. This is all about the body's adaptive response to the sunlight. In the first scenario, I've simply given it too much stimulus. I'm not used to this bright, hot sunlight. I've given it too much and I've damaged my skin far too severely. If I continue to sunbathe I will just get redder and redder. Your skin tissue just cant adapt to this excessive overload I've placed on it, its been damaged too much, and its going to take much much longer for the skin to heal. In the second scenario, the sunlight/stimulus was just as great in intensity - the sun was no weaker - but I'd allowed it to effect the tissue for less long. In fact just long enough to damage the skin very slightly. I then allowed my skin to provide an adaptive response, it repaired the damage and darkened the skin pigmentation so that next time around it wont burn so easily. This translates very well to explaining how overtraining occurs. If you give your muscles the right amount of stimulus, just a small amount of muscle damage and then you allow adequate time for repair before you re-expose them to more stimulus, then they respond (in the presence of ample amino acids etc..) by repairing the damaged tissue and growing slightly bigger so that they can more easily handle the training next time. If instead you obliterate your muscles with set after set of overload, then like the burnt skin, the damage is simply too great. Its going to take much longer without further exposure to allow for repair. FOR REPAIR! Not even growth. What happens if you then train it the next week? Likely its not fully repaired yet and you're going to create even further damage. If your body cant even recover enough to repair the tissue damage, then how can you expect it to grow new tissue. So the take home message is that we want to do just enough to maximally stimulate the muscles and then give them ample time to recover (repair and build). Doing any more than that at best is a waste of time, at worst is detrimental.

HIT Workouts As Originally Envisaged

The problem with HIT is that many people over the years, whether for fame, notoriety or whatever, have put their own slant on it. Mike Mentzer took it to such a crazy extreme that he ultimately had his clients doing as little as 4 sets per workout and only training once every 9 days. It was great for pitching a book called 'Muscles in Minutes' to people who wanted to grow muscle whilst doing as little as possible, but for most people its just too little work. Dorian Yates on the other hand, did a form of HIT where he did relatively high volume compared to early HIT - he'd do 2 work sets per excercise and several exercises per body part. He also did several warmup sets. So ultimately, counting the warm up sets (which for many volume trainers would be as intense as their work sets), the workouts end up looking little different to traditional programs. He also split his workouts into different body part days, like with volume training. The early Arthur Jones workouts were more like this:

- Whole Body Workouts 2-3 times per week
- 8-12 exercises
- 1 set to failure on each exercise (failure ideally at 10-15 reps)
- 2-3 seconds lifting weight, 2-3 seconds lowering weight

A typical workout could be:

Stiff Leg Deadlift
Leg Extensions
Leg Curls
DB Flyes
Straight Arm DB Pullovers
Lateral DB Raises
Barbell Curls
Tricep Pressdowns

I know that on first look, to those who currently do volume training this looks a really lame workout that you will struggle to get much out of and that you think is too easy. But if you do it right, I guarantee you that you will not find it easy. You will find it just as tough as your regular workout, if not much tougher. Now the key thing that I think most people miss, is the lifting speed. 2-3 seconds up, 2-3 seconds down and no pausing at the top or bottom of the movement. Try it. Take a weight/exercise combo that you normally do 10 reps with. Doesn't matter if its leg press, bench press, barbell curl - whatever. If you do that exercise with the strict slow tempo up and down, I will be very impressed if you get to 10 reps. Most people will get maybe 6 or 7 tops. Even if you do get 10, I'm sure you'll feel far more exhausted by it than your regular method of completing the set. By the time you make it through all 10 exercises, in that manner, believe me you'll feel like you had a tough workout.

Most trainers in general lift at quite a high speed, using a lot of momentum which detracts from the muscular tension the exercise generates. Others do the eccentric portion (lowering) slowly, but not the concentric (lifting) portion. There's arguments for that, which we wont go into here, and its definitely better than doing both portions fast, but it doesn't provide maximum muscle tensions. Which moves me onto my next point.

Time Under Tension

Remember I mentioned earlier how the third type of athlete I like to bring up in HIT vs volume debates is gymnasts? Well gymnasts interest me because for a long time I was perplexed how male gymnasts could build such muscular bodies with essentially body weight exercises and often no complementary weight training. If you have to lift big to get big, then how the hell can these gymnasts who lift nothing but their own bodies get so well developed. The answer my friends, is time under tension. Along with progressive overload, time under tension is in my opinion one of the two main principles in building muscle.

Lets step back to the last section. You are doing say the barbell curl in HIT fashion, 2 seconds up, 2 seconds down - 4 seconds per rep, so if you do 10 reps thats 40 seconds. Doing it in this slow controlled manner you feel continuous tension on the biceps. You're not locking out or resting at the top or bottom, just a smooth up and down tend times. At no point do your muscles get 'let off the hook', they are working the whole time. So the time under tension is 40 non stop seconds. Contrast this with how the average gym-goer performs a set of 10 barbell curls. They hurl the weight up, pause a little at the top, maybe lower it a little slower but largely let it drop, pause at the bottom, and repeat. The set takes more like 20 seconds. In that 20 seconds possibly only 5 seconds of it has the weight being lifted/lowered under control, the remainder is divided between what are essentially rest periods and periods of time where the weight is being moved by either momentum (swinging it up) or gravity (letting it fall). So compare the 40 seconds of time under tension of a HIT set, with the maybe 5 seconds of time under tension of a typical set and you can see further why not so many sets are really necessary. If you do the one set right, then you can reap the benefit - certainly in terms of time under tension - of many sets done improperly. Both time under tension and peak tension within the muscle are both important in terms of muscle growth, and are in my opinion done best by high intensity training. Of course you can this perfect form of 2 second lifting and lowering for multiple sets, but you'd have to compromise on the intensity/weight/reps, so one set to failure in my opinion is better.

Progressive Overload

The other critical factor in building muscle is progressive overload. All the folks who write books on bodybuilding love talking about the Ancient Greek wrestler Milo who carried a calf on his back every day until it was full grown. Its a good story and it illustrates progressive overload very well. In order to make a muscle grow, it has to continue to be subjected to greater stimulus. If you were to do the same exercise for the same number of reps with the same weight once a week, every week, it would have no need to grow new tissue. It can already handle that weight for that many reps. It doesn't need to get bigger. To make a muscle grow, you have to subject it to a greater stress than its dealt with before. There's a number of variables you can play with to increase the stimulus - the weight, the number of reps, the number of sets, the time under tension, the frequency of training etc... In HIT, we don't want to increase the number of sets or really the frequency of training as we don't want to 'over damage' the muscle or not allow sufficient recovery time. The variables we would change are the weight and the number of reps/the time under tension. There's also numerous advanced techniques we can use to increase intensity.

Now an interesting point on overload is that there's only so long you can go on adding weight. Eventually the increases you can make get less and less. People tend to think that HIT means using more weight than in volume training, but because of the slower repetition cadence this isn't necessarily the case. Go back to trying the bench press or barbell curl the way most guys do it, and the way HIT prescribes it and you'll see that in HIT, if you do it right, you'll probably use less weight. But it FEELS much heavier. Because of this, I would suggest that you can go on for longer adding weight to the bar with HIT than with regular training. And when you cant add weight to the bar any more, there's the advanced principles that you can use to make that weight feel heavier.

What the Research Says & Exercise Efficiency

Unfortunately there's no studies that have really put the two training models against each other and come up with a victor. There's been numerous studies though where multiple sets vs single sets (just one difference in between the two systems) has been analysed. These are of limited use in this argument, because the single sets and multiple sets were performed with the same intensity. It wasn't a case of one 'all out' set vs three 'best effort' sets. Nevertheless, generally the results were that multiple sets achieved significantly greater strength gains (typically 40-50%) but only slightly better muscle growth (typically 10%). So HIT aside, if you could do 1 set and get almost as much benefit as doing 3 then why would you do 3? If your boss asked you to work 3 times as many hours for 10% more pay, would you do that? If so, you're hired by the way.. This lands me at my next argument in favour of HIT - efficiency.

Now I love efficiency. In business, in exercise, whatever. Anyone who has ever worked for this or our previous business knows I like things run efficiently. I hate wasted time, money or effort. Anyone who's ever sparred with me in Jiu Jitsu (my favourite past time), should know I love energy efficiency. If I'm working harder than the other guy, then I'm doing something wrong; I try very hard to waste no effort and expend as little energy as possible, my goal is to make the other guy run out of energy so I can capitalize. So if I can do less exercise and get the same results, then that's perfect for me. If I can do 2-3 30 minute workouts a week and get 90% of the reward I'd get training longer, then why wouldn't I do that? I enjoy training, but I've got a lot of other things I like or need to do to. I've got a business to run, a family to spend time with, I train Jiu Jitsu/MMA almost every day, I've got various other commitments - time is often in short supply. Its fine when we're in our late teens or early twenties and have little responsibility but as we get older, our time gets scarcer and time-efficiency becomes more important. On the subject of efficiency, I'd like to recommend a book called the 4 hour work week by Timothy Ferris -http://www.fourhourworkweek.com/. Its a great book about generally how to make your life more efficient, particularly your working life. Interestingly, Timothy Ferris also arrived at the conclusion that HIT was the best form of training and transformed his own body using a HIT program - http://www.fourhourworkweek.com/blog/2007/04/29/from-geek-to-freak-how-i-gained-34-lbs-of-muscle-in-4-weeks/

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