High-intensity training (HIT) is a method based on the one-set training concept that was popularized by Arthur Jones (founder of Nautilus) and professional bodybuilder Mike Mentzer. The foundation of this training method involves very low volume and very high intensity. Most followers do as few as one set per exercise and only one to three exercises per muscle group. Intensity for this technique is not so much about the weight used but about training beyond the point of muscle failure. Every set must be taken beyond failure with the use of forced reps, negative-rep training, and even partial-rep training (whereas much of the range of motion of the exercise is performed until the weight cannot be budged). The theory behind HIT is that if multiple sets of an exercise are performed, every set cannot be trained with maximal intensity. By doing one and only one set of an exercise, you have a better chance of training with maximal intensity.

Volume is also kept low with HIT to minimize the time spent in the gym. Training sessions that are longer than 45 minutes tend to cause greater elevations in cortisol levels than with shorter training sessions. Since cortisol is a catabolic hormone that influences the breakdown of muscle protein and inhibits the ability of testosterone to bind to its receptors, limiting its rise after training is a desirable thing.

Because volume is low with HIT, it allows the lifter to follow a whole-body-training split or a two-day training split, depending on whether the lifter wants to train each muscle group two or three times per week.

There is no research to specifically support the theory of HIT, and anecdotal reports are varied. Some lifters experience considerable gains in strength and muscle mass. But for most, the progress soon comes to a halt. The problem may lie in the fact that volume is an acute variable that does not get manipulated in this program. Therefore, following HIT for only four to six weeks would be a smart way to use it. After training withHIT, you should switch to a training program that uses a fairly high volume.

The sample HIT program in the table is a two-day split done twice a week.
In this program, each set should be preceded with one short warm-up set before each exercise with approximately 50 percent of the weight you will use for the main working set. Do only about four to six reps with this lighter weight. Perform each set to muscle failure and have a spotter help you perform three or four forced reps after reaching muscle failure. Resist the negative portion of the forced reps for added intensity and consider attempting a few partial reps at the very end of the set.

MONDAY AND THURSDAY

TUESDAY AND FRIDAY

Encyclopedia of Muscle & strength by Jim Stoppani, PhD