Training Effectively To Build Muscle Mass with High Intensity Training and High Volume Repetitions

Bodybuilding has been a mainstream sport and fitness activity for several decades now. However there is still a debate over the best way to lift weights to build the biggest muscles. Some people believe that you should lift less for more muscle, and some say lift more. But what does this mean?

The traditional approach to bodybuilding the high volume weight training method. This involves performing several sets of up to 12 repetitions for each exercise, each session, with up to 36 repetitions per exercise. However, the followers of the HIT (high intensity training) methods that were popularized by Mike Mentzer, and used by 6 times Mr. Olympia Dorian Yates, believe that lifting heavier weights fewer times produces bigger muscles. Typically HIT routines involve 1 work set with 6-12 repetitions. Even amongst HITers there is a lot of debate over the number of reps that should be performed. Which method is best at building muscle?

Seeing that bodybuilding has been around for a long time now, you would think that there had by now been some unbiased scientific research into the various methods of weight training. Well, there has, but unfortunately the research is generally related to specific health issues. That being said, we shall look at the current research that is available and try to come to some conclusions.

First lets remember the purpose of this discussion – to determine the best way of building the biggest muscles. We are not asking if HIT is the best method to build the most athletic muscle or the strongest muscle. However, the conclusions may point in either one of those directions anyhow.

The HIT versus Volume Study

Another important point regarding this study into HIT is that we are restricted to the resources, and depth of information, that is available. The sources used are all ones which are found on the Internet and published by medical and sports journals. There may be alternative compelling research that we do not have access to. If you are aware of any, please send us the details!

The research available also covers a wide range of subjects. Some studies do involve people with weight training experience. However many look at the role of weight training as a means to strengthen and rehabilitate patients suffering from various conditions or recovering from operations. There is research relating to Parkinson’s disease, in HIT for young and elderly women, elderly men, athletic strength and cycling performance. But we shall attempt to make some sense of the research.

What is Intensity?

Before we determine if HIT is the best approach to building muscle tissue, we must be clear what is meant by high intensity weight training. According to Dave Durell2, “Intensity is defined as the percentage of possible momentary effort being exerted”. Physiology has shown that it is intensity that lead to muscle growth. However, the human body cannot sustain long periods of intensity. So, for maximum muscle growth, the perfect balance of intensity and duration is required. Too little intensity and there will not be sufficient microscopic tears in the muscle fibers to trigger muscular regrowth. Too much and there is a risk of damage and overtraining.

The theory behind HIT is that most of the damage to the muscle tissue is done in the first work set, and therefore performing multiple sets only makes recovery slower, but does not actually increase sarcoplasmic hypertrophy.

What is Hypertrophy?

Hypertrophy is simply the growth of muscle tissue, and is the aim of all bodybuilding. However, not all hypertrophy is equal either. There are two types of muscular hypertrophy. Sarcoplasmic hypertrophy is when the volume of sarcoplasmic fluid in the muscle cell increases – this makes the muscles bigger, but does not increase their strength. Myofibrillar hypertrophy is when the myofobrils increase to improve muscular strength. This only leads to a small increase in muscle size. Sarcoplasmic hypertrophy is the aim of bodybuilders, whereas myofibrillar hypertrophy is the aim of athletes and power lifters.

Also, Sarcoplasmic hypertrophy which involved the increase in sarcoplasms, means that the muscles store more glycosomes, which are granules of stored glycogen. So for bodybuilders, increased glycogen production is important, and for this more carbs are required.

Research has also shown that increase repetitions (volume training) leads to sarcoplasmic hypertrophy, i.e. bigger muscles. So, how is it then that professional bodybuilders that have won Mr. Olympia titles can be using HIT to build bigger muscles when biology seems clear that lifting heavier weights more intensively should result in great strength from myofibrillar hypertrophy but not greater muscle mass? The answer could be something to do with the “shock” effect where the sheer effort of training leads to a physiological response that sets the body up to build more muscle. But does it really happen this way, or is HIT essentially flawed? Some people think that a failure in understanding HIT comes from the fact that people “ignore” warm up sets. Mike Mentzer claimed that all his gains were from one single work set – but he performed many warm up sets to prepare his body for the work set. Maybe the real answer is a combination of high volume (warm up sets) and one work set where you lift until failure. This again is very different from the current approach of performing 2 or 3 work sets using the same weight.

Key Results from the Study

  1. With respect to building strength, in the short term there are no benefits to using a high intensity approach for athletes that have already been working on strength training (ref 1).
  2. The biggest strength gains come from workouts with the most intensity (ref 2).
  3. Peter Preuss noted that in comparative experiments high volume and high intensity both showed similar gains in subjects perform knee extensions. One suggestion for increased sarcoplasmic hypertrophy with HIT was that it is due to the speed of each repetition on not the level on intensity. Slower lifting may result in larger muscles due to the increase in time for oxygen to replenish the muscles and aid sarcoplasmic hypertrophy(ref 3).
  4. Maximal strength gains are elicited among athletes who train at a mean training intensity of 85% of 1 repetition maximum (1RM), 2 days per week, and with a mean training volume of 8 sets per muscle group (ref 4). This is similar to the HIT method. However, if there are bigger strength gains (myofobril growth) from this approach then the sarcoplasmic tissue must suffer, which means less bully muscles. “A note of clarification is warranted when discussing the dose-response relationship for training intensity and volume. This elucidation is crucial, as ambiguity and divergence exists within the strength and conditioning community regarding ‘‘intensity’’ and ‘‘volume’’ designation. In each of the studies analyzed, training intensity was coded as the average percent of 1RM used throughout the training program and training volume as the number of sets performed per muscle group. This operational definition for training intensity generates an objective, quantifiable unit that is contrary to the more subjective measure of training fatigue, often exploited in ‘‘H.I.T.’’ programs. Additionally, rather than designating volume as the total number of sets per specific exercise, total number of sets per muscle group is a more appropriate measurement of the absolute stress applied to a given muscle group. It should be noted that in accordance with this classification, many purported 1-set training programs / philosophies may, in effect, be multiple-set training practices.”
  5. In one study one set of high-intensity resistance training was as effective as three sets for increasing knee extensors and knee flexors isometric torque and muscle thickness in previously untrained adults (ref 5). This research does support the idea of using HIT to build larger muscles, but only in previously untrained subjects. It does not mean that muscular growth would have been less with a high volume approach.
  6. Performing high intensity eccentric exercises produces better results in terms of muscle structure in patients with Parkinson Disease. “The eccentric group consistently exceeded those in the standard-care group for all variables. To our knowledge, this is the first clinical trial to investigate and demonstrate the effects of eccentric resistance training on muscle hypertrophy”(ref 6). Again, this shows that HIT is best for strength in previously untrained individuals, but does not indicate if a high volume approach would have led to greater sarcoplasmic hypertrophy.
  7. In female subjects there was no difference in muscular growth between those on performing of 4-5 sets of 15-20 RM (repetition maximum) with sufficient rest between sets and those performing 8-9 sets of 4-6 RM with 90 s of rest between sets. In both groups the cross-sectional area of the muscles studied grew at a similar rate (ref 8). However, neither of these approaches if really HIT, as both involve too many sets to be considered HIT.
  8. In the second study of females the group doing HIT experienced smaller strength gains. “These findings suggest superior strength gains occurred following 3-set strength training compared with single-set strength training in women with basic experience in resistance training.” So this goes against the HIT for strength trend. However, we do not know about the increase in size of the muscles.
  9. In a study of elderly women there was no significant effect of either a high intensity of higher volume exercise program on thigh tissue composition. So once again, inconclusive.
  10. One study concluded that subjects can overtrain with HIT (generally HIT is advised as it is less likely to lead to overtraining than high volume training) – “Impaired Performances with Excessive High-Intensity Free-Weight Training” (ref. 16).
  11. Also some studies have shown that neither the levels of intensity or duration of each repetition have any major effect on strength gains in untrained subjects (ref. 17 and 18).


Based on the research papers available to us the results are once again inconclusive. Some women respond to HIT and some do not. Some say it works, others not. Results indicated that HIT works when:

  1. It is combined with, or follows, a different approach, i.e. high volume training. One study suggested that best athletic gains were from a mix. Also Mike Mentzer started his bodybuilding career using traditional high volume methods.
  2. Some people are more likely to utilize it better than others. It could be that the key factor in whether of not HIT works is genetic. Each individual needs to try all methods for themselves to determine which method gives the best results. There is no one size fits all answer when it comes to bodybuilding. Women do not appear to respond any differently to HIT.
  3. Different muscle fibers respond to different training, which is why some bodybuilders find using both methods works. A traditional volume training approach to start with builds the muscle foundation, then HIT maintains those and builds additional which makes the muscle bigger. Maybe HIT is one way, maybe the most effective way, of growing again after hitting a plateau in your training.
  4. One theory is that for larger muscles HIT actually needs the warm up sets. However, to make the warm up sets more effective, bodybuilders need to be stronger. This means that with increased strength, the warm up sets start to work the muscles more.

Even after reviewing all this research, our conclusion is that the HIT versus HVT debate will continue. The empirical evidence supports the view that HIT can build bigger muscles (1 Mr. Olympia and 1 IFBB Mr. Universe). But, maybe these two (Mentzer and Yates) have a genetic advantage that other bodybuilders do not, meaning that they respond to HIT in a way others just can never achieve? Biology / physiology says that high volume training leads to increased sarcoplasmic hypertrophy, which means bigger muscles. HIT should really only be utilized to increase muscular strength, not muscle size. What continues to be a sticking point is the “warm up sets”.

Finally, is the high volume training method a myth? Arnold Schwarzenegger is the most famous of the high volume trainers (and a very successful bodybuilder), but if you look at the photos of him lifting, it is anything but intense. Plus, Arnold would also say that the secret to bigger gains was to “go heavy” once a week, which is essentially performing one HIT session as part of your weekly weight training schedule. You cannot go heavy properly without it being intense! Schwarzenegger also talks at length about intensity in his book, The New Encyclopedia of Modern Bodybuilding. So, is there really a group of absolute HIT devotees that are building huge muscles? Or is it just a battle of words and ideas, while really everyone is having “heavy days” or “light days” to supplement their chosen method of bodybuilding?