Train To Gain: Is HIT Amiss?

An ongoing debate in bodybuilding and strength-training circles involves the optimal level of training volume, or number of sets per exercise. The high-intensity (HIT) school of thought strongly advocates workouts that feature minimal volume coupled with high-intensity training to failure on each set. They feel that one set per exercise will achieve maximal results.

The latest study examining the issue offers several insights.1 It involved 27 women, age range 20 to 40, divided into three groups: 1) single set, 2) multiple set and 3) control group. The controls did no resistance training but did do aerobic exercise. Both weight-training groups trained two days a week for six weeks, working the entire body in each session. The single-set group did one exercise to failure for six to nine repetitions. The multiple-set group did three sets using the same rep pattern and resting two minutes between sets. Whenever subjects in either group reached the goal of nine reps, they increased the resistance by 2.5 to five kilograms, or five to 10 pounds.

Since the majority of gains beginners make involve neuromuscular mechanisms rather than muscle gains, the subjects in this study all had at least six months of training experience; however, that may not have been sufficient to blunt the effects of neuromuscular mechanisms, a flaw mentioned by the study authors themselves. Subjects were tested for strength gains in two exercises: leg extensions and seated bench press machine.

In the leg extension strength test the multiple-set group showed a 15 percent gain, while the single-set group showed a 6 percent gain. In the seated bench press machine test only the multiple-set group showed a 10 percent strength gain. The authors think that multiple-set training does produce superior strength gains, especially in more experienced trainees.

As for the reason for the apparent superiority of multiple-set training, the researchers suggest several possibilities. They cite studies that have shown that you must induce a certain level of muscular fatigue to make maximal strength gains’and as it happens, the most efficient way to reach that fatigue level is by using multiple-set routines. They note that in most cases, the first set of any exercise serves as a ‘prefatiguing factor’ that doesn’t allow full muscle recovery. As a result, during the second and third sets additional motor units or muscle fibers are called into play to take over the work of fibers fatigued by the initial set. The net result is better neuromuscular adaptation that leads to greater strength gains.

The implication is that doing only one set per exercise leaves a muscle high and dry. Sure enough, the highest level of power and velocity during sets was achieved in the second and third sets of each exercise (in the multiple-set group, of course). The authors suggest that most people hold back on the first set due to fear of possible injury or some other mental block, then get into the exercise more during subsequent sets.

I’ve always believed that holding back was perhaps the greatest flaw associated with single-set training. If you don’t truly train to utter and complete failure’using 100 percent training intensity’then you’re merely doing one set that will do little, except for rank beginners. While some champion bodybuilders, including the late Mentzer brothers, were indeed capable of using the required level of intensity for single-set training, my casual observation in various gyms is that most people are not. As such, they won’t get the expected benefits from single-set training.

The authors of this latest study seem to agree, since they conclude by noting that single-set routines may be sufficient for anyone with casual goals, such as losing weight or maintaining minimal muscular fitness, but ‘if someone has the desire to maximally increase strength, a multiple-set training program should be recommended.’ As noted, however, you don’t want to go overboard with multiple sets. Be aware that most so-called champion-level routines outlined in bodybuilding publications are either flagrantly false or used in conjunction with various anabolic drugs that enhance muscle recovery considerably. IM

1 Schlumberger, A., et al. (2001). Single vs. multiple-set training in women. J Strength Cond Res. 15:284-289.