By Wayne L. Westcott, PhD
Posted on NaturalStrength.com on April 15, 2000
Several studies have shown that single-set strength training is just as effective as multiple-set strength training for beginning exercisers (Starkey et al., 1994; Westcott, 1995a). However, Kraemer (1996) has indicated that the rate of strength gain slows considerably after four months of a single-set training program. At this point, strength plateaus may be prevented by performing multiple sets of exercise in a periodized manner. Unfortunately, changing to a multiple-set strength program requires considerably more training time. Whereas doing one set of 15 exercises takes about 30 minutes per work-out, completing three sets of 15 exercise requires at least 90 minutes per workout. Fortunately, for time-pressured people there are some advanced training alternatives to exercising with multiple sets. These techniques are typically referred to as high-intensity strength training.
High Intensity Training Techniques
There are basically two means for increasing the strength-building stimulus without adding much training time. One procedure is to increase the length of each exercise repetition by slowing down the movement speed. Slower movement speeds produce more muscle force and more muscle tension than faster movement speeds. For example, the maximum effort isokinetic leg extension performed at 60 degrees per second produced 174 foot-pounds of muscle force, whereas the maximum effort isokinetic leg extension performed at 120 degrees per second produced only 132 foot-pounds of muscle force (Westcott, 1995a). Another procedure to enhance the training stimulus is to increase the length of each exercise set by reducing the resistance upon muscle failure and completing a few additional repetitions. A typical set of strength exercise fatigues fast-twitch muscle fibers but not slow-twitch fibers. By immediately lessening the weightload and performing 2 to 4 more repetitions, the more enduring slow-twitch muscle fibers may also be pushed to the point of fatigue.
High Intensity Training Research
We have conducted research studies on several types of high intensity strength training, including slow positive emphasis, slow negative emphasis, breakdown, assisted, and pre-exhaustion techniques.
In one high-intensity research study we examined 8 weeks of Nautilus exercise using standard or slow positive emphasis training (Westcott, 1994a). The 117 beginner level subjects in the standard training group performed 8-12 repetitions per set, taking 2 seconds for each lifting movement and 4 seconds for each lowering movement ( seconds per rep). The 35 beginner-level subjects in the slow positive emphasis training group completed 4-6 repetitions per set, taking 10 seconds for each lifting movement and 4 seconds for each lowering movement (14 seconds per rep). The slow positive emphasis training group increased their average exercise weightloads by 27 poundscompared to 22 pounds for the standard training group. Another high-intensity research project evaluated slow positive emphasis training and slow negative emphasis training (Westcott, 1995b). The 15 intermediate-level subjects did 4-6 slow positive emphasis repetitions (10 seconds lifting, 4 seconds lowering) on the leg extension, biceps curl, and chin-up exercises, and 4-6 slow negative emphasis repetitions (4 seconds lifting and 10 seconds lowering) on the leg curl, triceps extension, and bar-dip exercises. After 6 weeks of training, the slow positive emphasis exercise weightloads increased by an average of 22 pounds, and the slow negative emphasis exercise weightloads increased an average of 26 pounds.
In our first study on breakdown training, all 45 beginner-level participants performed standard Nautilus training for the first month (Westcott, 1994b). During the second month, half of the subjects continued standard training and half of the subjects did breakdown training. That is, upon reaching muscle failure they immediately reduced the weightload by 10 pounds and did between 2 and 4 additional repetitions to reach a second level of muscle failure. The breakdown training group increased their average weightloads by 25 pounds compared to 18 pounds for the standard training group.
This study compared 6 weeks of breakdown training or assisted training on strength development in 7 intermediate-level subjects (Westcott, 1995b). All of the participants performed breakdown training on the leg extension, biceps curl, and chin-up exercises, and assisted training on the leg curl, triceps extension, and bar-dip exercises. Assisted training involved instructor assistance with the lifting phase of 2-4 additional repetitions upon reaching muscle failure. The breakdown exercise weightloads increased by an average of 15 pounds, and the assisted exercise weightloads increased b an average of 17 pounds.
Another means for increasing the muscle stimulus is to perform two successive exercises for the same muscle group. This is typically accomplished by first doing a rotary exercise to fatigue the target muscle, followed immediately by a linear exercise to further fatigue the target muscle with the help of a nonfatigued muscle. In this study (Westcott, 1996), the 14 subjects did preexhaustion training for the chest (chest cross followed immediately by chest press) and for the triceps (triceps extension followed immediately by bar-dips). For comparison purposes they performed double sets (with 90 seconds rest) for the upper back (super pullover) and biceps (biceps curl). After 6 weeks of training both the pre-exhaustion group and the double-set group increased their average exercise weightloads by 9 pounds.
We completed a 6-week study with 10 subjects who performed one week each of slow positive emphasis training, slow negative emphasis training, breakdown training, assisted training, preexhaustion training, and a repeat training technique of their choice. The trainees increased their average exercise weightloads by 21 pounds using a combination of high-intensity training techniques.
Summary of High Intensity Training Studies
Combining the data from our studies with intermediate-level participants, we have 68 subjects who experienced an average exercise weightload increase of 17 pounds after 6 weeks of highintensity strength training. The 24 intermediate-level exercisers who were also assessed for body composition changes over the 6-week training period added 3.2 pounds of lean (muscle) weight and lost 3.7 pounds of fat weight. Although it is tempting to attribute all of the strength improvement to high-intensity training techniques, just having an instructor present during each workout appears to be a significant factor. A control group of 22 intermediate subjects experienced a 12-pound weightload improvement in exercises performed in the standard manner with an instructor watching (Westcott, 1995b). Apparently the study participants used better exercise form, trained harder, or both when an instructor was observing them. Nonetheless, it would seem that a variety of training methods is effective for increasing strength in beginner and intermediate-level exercisers. While multiple-set training may be equally productive, high-intensity training is more time- efficient. For this reason, high-intensity training techniques may be preferred by people who would like to further develop their muscle strength but don’t have a lot of time to do so. Due to the greater muscle demands, we recommend high-intensity training no more than twice a week for 6 to 8-week sessions.
Kraemer, W. (1996). Everything you wanted to know about strength training but were afraid to ask. General Session, IDEA Personal Trainer Conference, Anaheim, CA, March 23.
Starkey, D. B., Welsh, M. A., Pollock, M. L., et al. (1994). Equivalent improvements in strength following high-intensity, low and high volume training. Medicine and Science in Sports and Exercise, 26 (5): S116.
Westcott, W. (1994a). Exercise speed and strength development. American Fitness Quarterly, 13 (3): 20-21.
Westcott, W. (1994b). High-intensity training. Nautilus, 4 (1): 5-8.
Westcott, W. (1995a). Strength Fitness: Fourth Edition. Dubuque, IA: Brown and Benchmark.
Westcott, W. (1995b). High intensity strength training. IDEA Personal Trainer, 6 (7): 9.
Westcott, W. (1996). Make your method count. Nautilus, 5 (2): 3-5.