|Super Slow Resistance Training
Jeff Nelson, M.Ed. and Len Kravitz, Ph.D.
There are many different methods of resistance training. One form of resistance exercise that has drawn attention is superslow resistance training. Evidence of increasing interest is becoming more apparent with the rise of internet references and the availability of superslow certifications. This form of training has been presented as a safe and effective means of building strength in both beginning and advanced weight training (Westcott, 1999). Superslow training, originated in 1982 by Ken Hutchins, was developed in an osteoporosis study with older women because of the need to utilize a safer speed for subjects to perform the resistance exercises. The result was the beginning of a new resistance training technique, which became known as superslow strength training.
In a standard Nautilus training protocol, 8-12 repetitions are performed (Westcott, 1999). Each repetition represents a two-second concentric action, a one-second pause, followed by a four-second eccentric action. The total time for the set requires approximately 55-85 seconds for completion. The superslow protocol represents 4-6 repetitions consisting of a 10-second concentric phase followed by a four-second eccentric phase. This protocol also requires about 55-85 seconds for completion. One possible advantage of superslow training is that it involves less momentum, resulting in a more evenly applied muscle force throughout the range of motion. A potential disadvantage of this training is that it is characterized as tedious and tough.
Physiology of Superslow Training
An objective of superslow resistance training is to create more tension in a muscle for a given workload. This is accomplished by decreasing the speed of movement. The amount of force or tension a muscle can develop during a muscle action is substantially affected by the rate of muscle shortening (concentric phase) or lengthening (eccentric phase) (Smith, Weiss, and Lehmkuhl, 1995). The amount of tension generated in a muscle is related to the number of contracting fibers. Each muscle fiber (or muscle cell) contains up to several hundred to several thousand myofibrils, which are composed of myosin (thick) and actin (thin) protein filaments (Guyton and Hall, 1996). The repeating units of thick and thin filaments within each myofibril comprise the basic contractile unit, the sarcomere. In a muscle fiber, the slower the rate at which the actin and myosin filaments slide past each other, the greater the number of links or cross-bridges that can be formed between the filaments (Smith, Weiss, and Lehmkuhl, 1995). The more cross-bridges there are per unit of time, the more tension created. Thus at slow muscle action speeds, a higher number of cross-bridges can be formed, which leads to a maximum amount of tension for a given workload.
The tension in a muscle is related to the number of motor units firing and to the frequency with which impulses are conveyed to the motor neurons (Berger, 1982). Physiologically, using a slower speed protocol requires the activation of more muscle fibers and an increase in the frequency of firing in order to maintain a force necessary to lift a given workload (Smith, Weiss, and Lehmkuhl, 1995). This provides stimulation for muscle strength development. The initial strength development involves neurological adaptations (stimulation of muscle fibers through increased firing and recruitment) followed by muscle hypertrophy (Enoka, 1986). In muscle hypertrophy, an increase in protein synthesis results in a multiplication of myofibrils within muscle fibers leading to an enlargement of the cross-sectional area of the muscle (Berger, 1982). There is also a corresponding increase in the number of actin and myosin filaments, which subsequently increases the capacity for cross-bridge formation (Guyton and Hall, 1996).
Superslow Resistance Training Research
Although superslow resistance training has been around for a while, only two peer-reviewed manuscripts have been written. The first manuscript describes two studies by Westcott et al. (2001). The first Wescott et al. study was conducted in 1993 and consisted of 74 previously sedentary men and women with an average age of 56 years. The subjects were placed in groups of six and closely supervised for eight weeks. All of the subjects performed one set of 13 exercises (Nautilus equipment) three days per week. These exercises consisted of the leg extension, leg curl, leg press, neck flexion, neck extension, pullover, chest press, chest cross, lateral raise, bicep curl, triceps extension, abdominal crunch, and low back. Of the 74 subjects, 39 (10 males and 29 females) trained at a regular speed and 35 (13 males and 22 females) trained at the slow speed. Although both groups differed in the time spent in concentric phase, both groups had a 4-second eccentric phase. Each of the subjects was tested using either a 10-RM weight load (regular speed group) or a 5-RM weight load (slow speed group) at weeks 2 and 8 in the study for the determination of pre- and post-test strength assessments. The results indicated that the slow speed group attained superior strength gains, gaining an average of 26 lbs in strength for the 13 exercises combined, compared to an average of 18 lbs for the regular speed group.
The second study of the first manuscript was conducted in 1999 and consisted of 73 previously sedentary men and women with an average age of 53 years. This study was similar to the 1993 study except that it was a 10-week study and the pre- and post-test strength assessments were based on 10-RM weight load (regular speed group) and a 5-RM weight load (slow speed group) of the chest press only at weeks 2 and 10 in the study. Of the 73 subjects, 43 (13 males and 30 females) trained at a regular speed and 30 (10 males and 20 females) trained at the slow speed. This study supported the 1993 study conclusions in that the slow speed group achieved higher results that the regular speed group, gaining an average of 24 lbs in strength for the chest press, compared to an average of 16 lbs for the regular speed group.
The other recent peer-reviewed manuscript describes a study by Keeler et al. (2001). This study consisted of 14 sedentary women with an average age of 32.8 ± 8.9 years. The subjects were randomly assigned to either a superslow group (6 subjects) or a traditional training group (8 subjects). Strength was assessed for both pre- and post-test using a 1-RM on 8 strength exercises: leg extension, leg curl, leg press, bench press, compound row, biceps curl, triceps extension, and torso arm (anterior lateral pull-down). The subjects trained three times per week for 10 weeks. For this study, the superslow protocol was defined as a 10-second concentric muscle action, followed by a 5-second eccentric muscle action. The traditional protocol consisted of a 2-second concentric phase, followed by a 4-second eccentric phase. Both groups performed one set of each of the eight exercises reaching momentary muscular fatigue between 8-12 repetitions. The traditional and the superslow groups began the exercises using 80% and 50% of the 1RM, respectively, until muscular fatigue was reached. The weight was then increased in increments of 5% when the maximum repetitions could be completed in good form. Increments of 2.5% were used for the leg press exercise only. The results indicated that both groups had a significant training effect for the 8 exercises. Further, the traditional group improved significantly more than the superslow group in total weight lifted for the leg press, leg curl, leg extension, torso arm, and the chest press. The results for the chest press indicated that the traditional group improved by an average of 26 lbs compared to the superslow group improving by an average of 9 lbs. It was concluded that traditional training is superior to that of superslow strength training for improving strength as assessed with the 1-RM for the initial phase of strength training in sedentary women.
The Westcott et al. (2001) manuscript describes two studies (1993 and 1999 studies) that report the superslow resistance training resulting in superior strength gains than a traditional strength training method. In contrast, the Keeler et al. (2001) study indicates that the traditional strength training group improved better than the superslow group for 5 of the 8 exercises. The different outcomes between studies may be due to different subject populations, training methodologies, and testing procedures. Westcott et al. recruited sedentary men and women with an average age in both studies of 54.5 yrs., where as the Keeler et al. study had sedentary women whose average age was 32.8 yrs. Very little is documented how various age populations may be differentially affected by the training regimen (superslow versus traditional speed), although this factor certainly needs further elucidation.
The Keeler et al. (2001) study trained the traditional resistance exercise group using 80% of 1RM while the superslow group trained at 50% of 1RM. Both groups performed 8 to 12 repetitions to muscular fatigue. The authors said it was recommended that the superslow training group weight load be reduced 30% from what is normally used (however, the source for this recommendation was not cited in the study). Contrariwise, in the Westcott et al. (2001) studies, the traditional training group performed 8 to 12 repetitions to fatigue where as the superslow training group performed 4 to 6 repetitions to fatigue. Given that resistance load intensity has a direct association with muscle force production, this is a major difference noted in training methodologies of these investigations, and certainly warrants further investigation.
Finally, in the Keeler et al. (2001) study, strength measurements were quantified with 1-RM assessments of strength for the superslow and the traditional strength training groups. Conversely, in the Westcott et al. (2001) investigations the traditional strength training group was assessed with a 10-RM while the superslow was measured with a 5-RM. Certainly, the differences across the board in strength assessments may also be contributing factors to the varying results observed in these investigations.
Although a final conclusion of the efficacy of superslow training versus traditional strength training warrants further research, some strong applications can be ascertained. Both training methods demonstrated significant increases in strength from pre- to post-testing. Since variety of resistance training stimulus is an important aspect of training design, perhaps incorporating both of these methods is a viable option for many clients. While some clients may find the superslow method somewhat tedious and challenging, other clients may relish in this type of challenge. Therefore, the personal trainer is reminded of the importance of individualizing the workout scheme to keep the client motivated, as well as challenged. Future randomized studies are needed to establish whether a true difference does exist between superslow and traditional protocols in developing strength in men and women (of all ages).
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