Several scientific studies have examined this issue and arrived at different conclusions. In many of them, however, the training techniques bore no resemblance to real-world training. For instance, they generally used untrained subjects, and it’s an established fact that initial gains mostly accrue from increased neuromuscular function, or better communication between the muscles and nervous system, so just about any type of training program is effective for beginners, unless it involves gross overtraining that would lead to rapid burnout.
Another typical error is having subjects rest for as much as 30 minutes between sets. While people who go to gyms more for socializing than training may rest that long, those interested in making progress most assuredly do not.
The high-intensity training (HIT) groups often cite a stress theory first promulgated by Hans Selye, Ph.D., a noted researcher who specialized in how stress affects the human body. After years of observation and research, Selye proposed the General Adaptation Syndrome, consisting of three phases. In the first phase a new stimulus, or potential stress, is introduced. Phase two is characterized by physiological adaptations to the stress. Phase three occurs if the stress goes on too long, overwhelming the adaptation process and leading to exhaustion. That last phase could result in various stress-related illnesses, such as cardiovascular disease or immune function exhaustion.
According to HIT advocates, Selye’s GAS is applicable to bodybuilding in the sense that doing more than one set per exercise inevitably results in exhaustion, evident as either lack of progress or loss of previous gains. But it can be viewed another way. Once you begin training, you’re in stage one, encountering a new stress. The body adapts to that stress by getting stronger in phase two. Phase three is tricky because the body tends to attempt to maintain homeostasis and must be prodded to change. Doing one set, some say, leads to an eventual cessation of progress because it’s simply not enough stimulation for the muscles to get stronger. That’s especially true if you don’t maintain a high level of training intensity.
Another theory may explain why multiple sets seem to increase strength more effectively than single sets. According to the corridor theory of strength training, first presented by a noted Russian exercise physiologist in 1995, muscles grow best and get stronger faster when you train both recruited and exhausted motor units (muscle fibers). If you rest too long between sets or do only one set, you aren’t recruiting both sets of fibers; you’re simply working the same fibers again. If you reduce rest time between sets, your body must call on previously unused fibers, thus working more of the muscle and leading to greater size and strength gains.
You have a better chance of hitting unused muscle fibers if you train with less rest between sets, doing several sets. Most bodybuilders have discovered that through experience; it just feels better to them, and they seem to make better gains doing multiple sets.
In one study examining the issue of single vs. multiple sets, 16 men, average age 21, all of whom had at least two years of training experience, were divided into two groups, one doing one set, the other doing three.1 Both groups trained three days a week for 12 weeks. The training reps varied from four and eight, and both programs involved an equal level of training intensity.
Those in the multiple, or three-set, group made greater strength gains than those in the one-set group. The three-set group made 30 percent greater gains on the leg press and 13 percent greater gains on the bench press than did the one-set group. If the theories of HIT advocates are correct, those results should have been reversed. Score this one for the multiple-set crew.
1 Rhea, M., et al. (2002). Three sets of weight training superior to one set with equal intensity. J Str Cond Res. 16:525-29.
©,2011 Jerry Brainum.Any reprinting in any type of media, including electronic and foreign is expressly prohibited.
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