If you follow bodybuilding to the slightest degree then you are well aware of who Mike Mentzer is. In fact, he is the only bodybuilder to ever have a perfect score of 300 at Mr. Olympia. However, he is better known for popularizing a system of training known as Heavy Duty or High Intensity Training (HIT).
The Heavy Duty system involves the use of fewer sets per workout and is considered low volume training. Similar to the Bulgarian style of training, the Heavy Duty system requires keeps warm-up sets to a minimum as the athlete prepares for maximal exertion. In fact the idea is to warm-up the joints and mentally prepare for maximal exertion without fatiguing the muscle at all.
And then smash! The muscles are “HIT” with the most intense techniques known to muscle builders such as forced reps, negative reps, and rest-pause. The rep range is kept between 6 to 9 reps in general depending on the technique used.
Forced reps are ideal for Heavy Duty training as they require few sets. To perform forced reps you will need a training partner to assist you. Use a heavy enough weight that you reach failure around 6 reps. Once failure is reached continue by having your training partner assists you in doing another 1 to 2 reps.
Negative reps involve using a heavy weight on the eccentric (negative) portion of the lift while your partner assists you on the concentric (positive). Additionally, negative reps can be done by lowering the weight slower on the eccentric part of the movement. The tempo could be anywhere from 1-3 seconds concentric, and 4-7 seconds eccentric.
Rest-pause can be introduced into the program in many ways. The first is by reaching failure on any given set around 6 reps, rest a few seconds, and then continue to bang out another 1 to 3 reps reaching failure again. Rest-pause can also include performing singles with short 15-30 second rest intervals between reps until 6 – 9 reps are completed.
Whichever HIT technique you decide to employ is entirely up to you as the end results are the same. The muscles get pulverized, the lactic acid burn is insane, and it is usually followed by extremely sore muscles the very next day.
Heavy Duty is an advanced method of training that is not recommended for beginners. You will need a good knowledge of how your body works and will need to practice warming up the muscles without fatigue in order to effectively use the techniques employed in this system.