High-intensity training (HIT) proposes that we can gain muscle size and strength faster and more efficiently if we keep our workouts short, infrequent, and brutally intense. It’s not the most popular way to build muscle, but it’s had a loyal following for the past 50 years and shows no signs of giving up.
During these past 50 years, though, thousands of muscle-building studies have been published, and many of them have looked into the principles that define HIT. So, how many sets should we do per exercise? How often should we be training? Should we lift to failure?
Most of all, is HIT good for building muscle?
What is High-Intensity Training (HIT)?
High-intensity training (HIT) was popularized in the 1970s by Arthur Jones, the creator of the Nautilus exercise machines. It was further promoted by the famous bodybuilder Mike Mentzer in his Heavy Duty Training System.
With strength training, “intensity” usually refers to how much weight is on the bar—how heavy you’re lifting. With bodybuilding, though, intensity more often refers to how close to failure you take a lift. Arthur Jones and Mike Mentzer were famous for advocating that bodybuilders train beyond muscular failure, and so their style of training became known as high-intensity training.
High-intensity training is built around a few different principles:
- Brief, Infrequent, and Intense: With conventional hypertrophy training, lifters typically stop 0–3 reps shy of failure, do 3–6 sets for each exercise, and train each muscle 2–3 times per week. With HIT, though, the idea is to keep the workouts brief, infrequent, and intense. You might do a single set of each exercise, take that set beyond muscular failure, and then rest until your muscles are fully recovered, which might take upwards of a week.
- Slow and methodical lifting: HIT is also known for using slower lifting tempos. With conventional hypertrophy training, you lift the weight explosively and then lower it back down under control. The lifting portion (the concentric) might take 1–2 seconds, and the lowering portion (the eccentric) might take 2–3 seconds. With HIT, you’d slow it down, taking 3+ seconds to lift the weight and 4+ seconds to lower it. You might even add pauses. This forces you to use lower weight, but it also gives your muscles a greater time under tension.
- Exercise machines: Finally, HIT is known for using exercise machines. The idea is that using exercise machines can help keep the risk of injury low when taking your sets to failure and beyond.
Since the 70s, HIT has stayed popular among bodybuilders who want to build muscle with short, minimalist workouts. Most bodybuilders eventually come across Mike Mentzer’s bodybuilding workouts and HIT lectures. Mentzer is a smart and charismatic guy, and he offers a compelling approach to building muscle.
HIT training is also popular among casual lifters. It’s been featured in mainstream fitness books like The 4-Hour Body by Tim Ferriss and Body by Science by Doug McGuff. It’s never been the most popular way to build muscle, but it’s always had a loyal following.
HIT Workout Routine
There are a few different ways of doing high-intensity training, but most of them emphasize doing full-body workouts, exercise machines, taking each set to total muscular failure, and lifting the weight forcefully and then lowering it slowly.
Here’s what a sample workout routine might look like:
HIT Workout 1
The first workout is a full-body workout that emphasizes the big compound lifts. These lifts are done using machines instead of free weights. The idea is that exercise machines make it safer to take our lifts to failure.
|Leg Press||1 set||8–10 reps|
|Leg Curls||1 set||8–12 reps|
|T-Bar Row||1 set||8–12 reps|
|Chest Press||1 set||8–12 reps|
|Biceps Curls||1 set||10–15 reps|
|Overhead Extensions||1 set||10–15 reps|
Every set in this workout is taken to total muscular failure. 2–4 days later, when your muscles stop feeling sore, you can do the next workout. Ideally, once you get into the swing of it, you’d be doing these workouts three times per week.
HIT Workout 2
The second workout is also a full-body workout, but this time we’re using different compound lifts. The idea is to vary the stress on our muscles, joints, and tendons, reducing our risk of injury and stimulating more balanced muscle growth.
|Romanian Deadlifts||1 set||10–15 reps|
|Leg Extensions||1 set||8–12 reps|
|Underhand Lat Pulldown||1 set||8–12 reps|
|Shoulder Press||1 set||8–12 reps|
|Chest Fly Machine||1 set||10–15 reps|
|Skull Crushers||1 set||10–15 reps|
You don’t need to use those specific exercises. You can do High-Intensity Training with free weights. Instead of the leg press, you could do front squats. Instead of underhand land pulldowns, you could do chin-ups. Instead of t-bar rows, you could do barbell rows.
However, if you’re training with free weights, it may be wiser to do 2–3 sets per exercise and stop 0–3 reps shy of failure. That will keep your training safer, stimulate more muscle growth, and give you more practice with the lifts.
The Research on HIT
The Ideal Training Volume
Some studies, such as this review by Steele and Fisher, say we can gain similar amounts of strength from doing a single set as we would from doing multiple sets. With that said, the best research we have on training volume shows that the more sets we do, the faster we build muscle, at least to a point. For instance, this meta-analysis by Schoenfeld and Krieger—two of the most respected hypertrophy researchers—found that we can expect to build at least a bit more muscle with each additional set we do.
If we look at the study by Radaelli, Botton, et al. that found a benefit to doing fewer sets, it was a study done on older women. If we look at the other study by Radaeli et al.—the one that found a large benefit to higher training volumes—we see a study done on men who were new to lifting weights. This may hint at the fact that our ability to recover from hard training decreases at a certain age, so we should lower our training volumes. Mind you, lowering our training intensity instead—stopping our sets further from failure—might be even wiser, as it would reduce the risk of injury. And again, if we look at the research overall, we see a strong trend for more sets stimulating more muscle growth.
Furthermore, some of the research favouring lower training volumes is suspicious, and after being questioned by prominent researchers like Greg Nuckols, James Krieger, and Brad Schoenfeld, it’s been retracted. For instance, this paper by Barbalho et al. recommended lower training volumes. The results reported appeared to be fraudulent. Upon closer investigation, the study was retracted.
If we look at the research overall, it seems that some people can build muscle with 1–3 hard sets per exercise per week, depending on their genetics and training history. However, people build muscle faster and more reliably by doing more than that, with muscle growth seeming to peak at around 9–18 sets per muscle group per week. After that, the benefits of doing extra sets tapers off. At a certain point, doing more sets begins to interfere with recovery, and so each additional set begins to yield less muscle growth.
The Ideal Lifting Intensity
If we look at the effect of training intensity on muscle growth, the results are mixed and unimpressive. This is especially true for intermediate lifters, with compound lifts, and when doing more than one set per exercise (Santanielo, Carroll, Lacerda, Pareja-Blanco 2, Pareja-Blanco 3):
Overall, as a rule of thumb, it’s a good idea to leave 0–3 reps in reserve when doing our compound lifts. For beginners, stopping shy of failure keeps the lifts safe and helps develop better lifting technique, though it won’t yield extra muscle growth. For intermediate lifters, stopping shy of failure actually seems to stimulate more muscle growth, perhaps by causing less muscle damage, and thus leaving more resources available for muscle growth. However, with HIT, there’s only one set for each exercise, and so muscle damage is already minimal.
With isolation lifts, there’s little harm in taking them to failure, especially on the final set of each exercise. With beginners, it can stimulate more muscle growth. With intermediates, it helps to keep training effort consistent and makes tracking strength gains easier. If you’re doing HIT, you’re only doing one set per exercise, and so taking that one set to failure makes total sense.
With high-intensity training, since the training volume is so low, it makes sense to take your sets all the way to failure. Muscle damage will be low because of the lower training volume. May as well attempt to stimulate a bit of exrta muscle growth by lifting harder. Still, the benefits of that extra intensity are likely modest at best.
Is HIT Good for Building Muscle?
High-intensity training does have some good logic behind it. When we’re doing just a single set per exercise, there’s less risk of causing excessive muscle damage, so it makes sense to push that set harder. When we push that set harder, we stimulate a bit more muscle growth than we would by stopping a few reps shy of failure. So if you only have enough time to do one set per exercise, it does indeed make sense to train with a higher intensity.
The Advantages of HIT
HIT isn’t a bad way of training, and there’s a reason why it’s had such a loyal and consistent following these past 50 years:
- The workouts are shorter.
- We stimulate more muscle growth per minute spent training.
- Our muscles, joints, and tendons get less beat up and have plenty of time to recover.
The Disadvantages of HIT
Just because HIT is a good way of stimulating muscle growth, though, doesn’t mean that it’s the best way. If we compare high-intensity training against conventional hypertrophy training, it has a few notable disadvantages:
- Doing one set per exercise isn’t enough to maximize your rate of muscle growth. Doing more sets builds muscle faster.
- Shorter workouts means less time spent exercising. Minimizing the amount of time spent exercising isn’t ideal for your health.
- Even with lower training volumes, taking sets all the way to failure (and beyond) can increase your risk of injury, especially if you’re doing the big compound barbell lifts.
- You get less practice with each lift, making it harder to improve your technique.
So although some people prefer HIT, and although it is indeed quite efficient, it’s not the most effective way to build muscle. You’d build muscle faster by stopping your sets 0–3 reps shy of failure, doing more sets per exercise, and training your muscles at least twice per week.
High-intensity training can be a good way to build muscle with short, minimalist workouts. However, conventional hypertrophy training (doing more sets and stopping just shy of failure) tends to be better for building muscle, has a lower risk of injury, and will have you doing more overall work—more exercise—which is better for your health.
If you want to spend less time working out, I’d recommend doing supersets, drop sets, and using shorter rest times. Your workouts will still be short and hard, but you’ll stimulate more muscle growth, your risk of injury will be lower, and the workouts will be better for improving your health. Overall, you’ll get better results than you would from doing HIT.
With that said, it’s often a good idea to experiment with several different styles of weight training. Even if HIT isn’t the best default way to lift, it might still be worth trying for a few months. Perhaps it will challenge you in a new way, spurring on new muscle growth. Or perhaps you’ll realize that you prefer it.
If you want a customizable workout program (and full guide) that builds in these principles, check out our Outlift Intermediate Bulking Program. Or, if you’re still skinny or skinny-fat, try our Bony to Beastly (men’s) program or Bony to Bombshell (women’s) program. If you liked this article, you’d love our full programs.