According to the tenets of high-intensity training, muscular gains don't come from sheer volume of training but instead from factors such as set-by-set intensity and the amount of weight used. This philosophy represents the classic overload concept in the purest sense: You must stress a muscle with heavy weights to induce hypertrophy, or growth, then allow sufficient time for full recovery. The result should be a body that compensates for the induced stress by gaining additional size and strength.
Jones and Mentzer frequently point out that sprinters show considerably greater muscular mass than long-distance runners, such as those competing in marathon events, the simple explanation for this morphological variation is that the sprinters train more intensely; that is, they do more work in a given period.
Many of the Jones-Mentzer principles are based on what Jones refers to as self-evident logic. One principal aspect of the high-intensity training that reflects self-evident logic is the idea of training to failure. Mentzer and Jones consider this essential in inducing muscular size and strength. They point out that the human body has a finite recovery ability, and the less you tap into this recovery ability, the greater the gains.
Recovery ability is just another way of explaining the stress and compensation theory originally stated by scientist Hans Selye. In short, you impose a stress sufficient to stress the body without exhausting its ability to recover. The body will then compensate for the imposed stress by changing something. In the case of exercise, this change involves additional protein synthesized in myofibrils or muscle fibers. As a result the muscle grows.
The problem is finding the right level of stress; in other words, how do you impose enough exercise on muscle without stepping over the line? According to Jones, if you overtrain, you'll exhaust recovery ability. That leads to either no gains or a catabolic state, in which you lose previous gains. Jones and Mentzer's solution is twofold: 1) Use heavy weights to stress the muscle fibers most prone to hypertrophy, the type-2B fibers; and 2) train to momentary muscular failure.
Training to failure, according to the high-intensity school of thought, makes sure you stimulate the type-2 muscle fibers while using up the smallest amount of your delicate recovery ability. Over the years Jones has amended his ideas concerning the proper frequency and volume of training to promote maximum progress. When he first appeared on the scene in the early 1970s, he suggested training no more than three times a week, averaging two sets per exercise. More recently, he favors no more than one set per exercise.
Mentzer has refined the system to the point that some of his trainees hit a muscle only once every eight days. Again, the idea is to allow sufficient recuperation time while minimizing the expenditure of existing recovery ability.
Critics point out that the recovery ability concept is nebulous. Scientists trained in subjects such as statistics have problems with something that can't be precisely quantified. Jones and his followers answer that training to failure ensures maximal muscle stimulation for everyone, regardless of individual differences, while preventing overtraining.
A recent review of training to failure appears in a 2002 issue of the journal Strength and Conditioning. The authors of the review say that it's more important to use heavy weights than it is to train to failure. They list past research, indicating that, according to the majority of studies, multiple sets are superior to single sets when it comes to inducing muscle size and strength gains. Weightlifters, the authors say, rarely train to failure yet are undeniably strong.
The new review also states that consistently training to failure often results in overtraining in about three to four weeks. This is a curious outcome, considering that the whole idea behind one-set-to-failure training is to avoid overtraining. The scientists say that the cumulative muscle damage imposed by training to failure sets the stage for injuries because of the increased fatigue you experience when you train to failure regularly.
The review concludes by suggesting that if you want to try training to failure, do it as part of a periodized program for no more than three weeks at a time.
Arthur Jones would undoubtedly ties one word to describe the authors of this study: idiots. If anything, the greater rest featured in present high-intensity-training programs would tend to increase recovery while minimizing injuries due to more complete muscle and connective tissue recovery. On the other hand, I've observed that high-intensity devotees like Don-an Yates appear to have frequent injuries, such as Yates' elbow, biceps and shoulder problems.
As anyone who's trained with heavy weights for years knows, however, injuries are an occupational hazard. In defense of Yates and other high-intensity-training proponents, there's no proof that he could have avoided his injuries if he'd trained in a more conventional style. In fact, I've heard Yates say that he's especially careful to warm up his muscles before tackling the heavy sets.
As I see it, the main problem with high-intensity training is not injuries. To get maximum benefit from one set, you really must train to failure. That's easier said than done. In my experience, few people have the mental intensity to train to utter and complete failure. They may think they're doing it, but the reality veers considerably from their fantasy. People who do only one set without reaching true failure will only make gains if they're rank beginners.
Another possible and rarely discussed drawback of high-intensity training is that you must cut your calories drastically to lose bodyfat. Since the average high-intensity routine takes about 20 minutes, you probably burn only 100 to 200 calories at most. Both Jones and Mentzer aren't in favor of additional aerobics, noting that such exercise will adversely affect recovery ability and either limit or prevent progress.
Thus, if you're seeking to lose body-fat on a high-intensity workout, you need to eat about as much as a 90-pound gymnast. I do recall, however, that Mike and his brother Ray, a former Mr. America, did plenty of aerobics in their bodybuilding heyday. I don't think either Mike or Jones has addressed the problem of calorie and fat loss in terms of the present incarnation of high-intensity training.
That said, however and as an anecdotal aside I can report that I made the best gains of my more than 20 years of training while using a program similar to the one advocated by Mentzer and Jones. I used no drugs and trained only two to three times a week but gained tremendous strength. I was accused of being on the juice, yet I took nothing but natural food supplements. Contrary to what some experts say, I suffered no injuries and certainly increased my muscle size and strength.
I eventually stopped using the system, not for physical reasons but due to psychological factors. While my workouts were short, after two straight years of high-intensity training I eventually couldn't stand the thought of having to train to failure with ponderous poundages at every workout. In retrospect, I think the solution would have involved using the system during one phase of a longer program. In that respect, I agree with the conclusion offered by the training-to-failure review discussed above: True training to failure is most efficient as part of a year-round periodization system.