Published Studies on SuperSlow

Several published studies have compared the effectiveness of SuperSlow and traditional strength training protocols. These include 1993 and 1999 studies by Westcott et al, a 2001 study by Keeler et al, and a 2003 study by Hunter et al.

The 1993 and 1999 studies by Westcott et al are often cited as proof SuperSlow repetitions are more effective for increasing muscular strength than the traditional 2-second positive and 4-second negative repetition speed. The study by Keeler et al is often cited as proof SuperSlow is not as effective as traditional repetition speeds. Keeler et al also compared the effects on body composition and aerobic capacity (VO2 max), finding no significant improvements in either group. The Hunter et al study compared the effects of SuperSlow and a traditional protocol on metabolism and heart rate response, finding the traditional protocol resulted in greater heart rate increases and energy expenditure.

Keeler et al

In the Keeler study, 14 previously untrained women were divided into SuperSlow and traditional groups, each performing one set of 8 exercises three times weekly for ten weeks.

The SuperSlow group used a 10 second positive and 5 second negative speed and a repetition range of 8 to 12, starting with 50% of their 1 repetition maximum (1RM). The traditional group used a 2 second positive and 4 second negative speed and a repetition range of 8 to 12, starting with 80% of their 1RM. Subjects were timed with stopwatches. When subjects were capable of performing 12 repetitions in good form the resistance was increased by 2.5% for the leg press and 5% for all other exercises. The average time to failure or time to finish (TTF) for the SuperSlow group was 120 to 180 seconds, while the average TTF for the traditional group was only 48 to 72 seconds.

Subjects were tested for their 1RM with no speed limitations on all exercises before and after ten weeks. At the completion of the study, the SuperSlow group only increased their 1RM loads by an average of 8.2 pounds, compared to an average of 19 pounds for the traditional group.

Critics of the Keeler study claim the lack of standardization of training loads and set duration obviates fair comparison of the protocols. However, the 1RM percentages used reflect the initial resistance selection recommendations in the second edition of the SuperSlow technical manual, page 132 of "70% of the suggestion for the standard 2/4 protocol". The 50% of 1RM used by the SuperSlow group is approximately 70% of the 80% of 1RM used by the traditional group.

Although TTF was not standardized, the 120 to 180 second TTF resulting from the 10/5 repetition speed and 8 to 12 repetition range is within the 100 to 180 second TTF currently recommended for SuperSlow.

Keeler: One set of 8 exercises, 3 times per week for 10 weeks. N=14

Westcott et al

In both of Westcott's studies, the SuperSlow group used a 10 second positive and 4 second negative speed and a repetition range of 4 to 6. The traditional group used a 2 second positive, 1 second pause, and a 4 second negative speed and a repetition range of 8 to 12. Subjects were supervised by instructors who provided a cadence count, but were not timed with stopwatches. When subjects were capable of performing the upper repetition guide number in good form the resistance was increased by 5%. The TTF for both groups was 56 to 84 seconds per exercise, with an average TTF of 70 seconds.

In the 1993 study 74 previously untrained men and women were divided into SuperSlow and traditional groups, each performing one set of 13 exercises, three times weekly for eight weeks. The SuperSlow group was tested for their 5 repetition maximum in all exercises using a 10/4 speed (70 seconds TTF) and the traditional group was tested for their 10 repetition maximum in all exercises using a 2/1/4 speed (70 seconds TTF) at 2 and 8 weeks. The SuperSlow group increased their exercise weight loads by an average of 26.5 pounds, compared to only 17.5 pounds for the traditional group.

In the 1999 study 73 previously untrained men and women were divided into SuperSlow and traditional groups, each performing one set of 13 exercises, two or three times weekly for ten weeks. The SuperSlow group was tested for their 5 repetition maximum in all exercises using a 10/4 speed (70 seconds TTF), and the traditional group was tested for their 10 repetition maximum in all exercises using a 2/1/4 speed (70 seconds TTF) at 2 and 10 weeks. The SuperSlow group increased their 5RM chest press weight loads by an average of 24.0 pounds, compared to only 16.3 pounds for the traditional group.

In both studies by Westcott et al the SuperSlow groups' exercise weight loads increased on average 50% more than the traditional groups', while Keeler's SuperSlow group's average weight load increases were over 50% lower than those of the traditional group.

Critics of Westcott's studies claim since repetition speeds were not timed during training or testing, any conclusions should be regarded as questionable. Westcott stated although stopwatches were not used, all workouts and tests were supervised by instructors who provided a cadence count.

Westcott 1: One set of 13 exercises, 3 days per week for 8 weeks. N=74

Westcott 2: One set of 13 exercises, 2 or 3 days per week for 10 weeks. N=73

Due to differences in study design and lack of standardized testing methods it is difficult to directly compare the effect of TTF between the SuperSlow groups in the Westcott and Keeler studies. However, a shorter TTF appears to be more effective for increasing muscular strength in previously untrained subjects when using the SuperSlow protocol. Westcott's 10-week SuperSlow group's average 5RM chest press loads increased by an average of 200% more than the 1RM chest press weight loads of Keeler's SuperSlow group.

Comparison of Westcott 1999 and Keeler SuperSlow Groups

The significantly greater strength increases achieved by Westcott's SuperSlow groups compared to Keeler's reflect the experiences of a number of SuperSlow instructors and trainees currently using TTF averaging 40 to 80 seconds who report greater muscular strength and size increases than with the recommended 100 to 180 seconds.

The issue of effectiveness of shorter versus longer TTF has been the subject of debate in the SuperSlow instructor community for several months. Objections to shorter TTF include the belief it may increase risk of injury or instances and severity of form discrepancies. Experienced SuperSlow instructors using shorter TTF with clients have reported neither problem.

Although the published research shows no significant difference in the effectiveness of different repetition ranges for increasing muscular strength, the highest repetition count used (25) results in a TTF under 60 seconds at typical, unrestricted repetition speeds. Additionally, lower repetition ranges with heavier loads may be required to increase bone density.

Hunter et al

In the Hunter study, 7 previously trained men were measured for heart rate during and energy expenditure during, immediately following, and 22 hours after both SuperSlow and traditional strength training workouts. Subjects were measured for resting energy expenditure after a 12-hour overnight fast using a Delta Trac II, and for 1RM in each of 10 exercises, then randomly assigned to a protocol order group, either SuperSlow followed by traditional strength training, or traditional followed by SuperSlow. Each group was tested using both protocols, with the second workout performed three days afterwards.

The SuperSlow group performed one set of 8 repetitions (120 seconds TTF) of ten exercises, using a 10/5 speed and 25% of their 1RM. The percentage was determined by preliminary tests for the amount subjects could use for 8 repetitions. Rest intervals were limited to 1 minute, and total workout times averaged 29 minutes.

The traditional group performed two sets of 8 repetitions (approximately 30 seconds TTF) of ten exercises, using an unspecified speed of movement and 65% of their 1RM. Rest intervals were limited to 1 minute, and total workout times also averaged 29 minutes. The paper states "the cadence between repetitions was controlled so each set took 30 seconds". It is not clear whether this refers to the actual repetition speed or a rest period between repetitions. The speed of each repetition for the traditional group averaged slightly faster than 4 seconds.

The energy expenditure for the SuperSlow workouts was substantially lower than for the traditional workouts during, immediately following, and 22 hours later, and the heart rates during the workouts were much lower for the SuperSlow group. This is not surprising considering the SuperSlow group used significantly less resistance than the traditional group.

It is important to consider that claims regarding the fat-loss benefits of SuperSlow are based on increases in resting energy expenditure resulting from increases in muscle tissue, rather than increases in energy expenditure during and after the workouts. Studies comparing the effectiveness of strength training protocols for fat loss should focus on increases in lean mass and resting energy expenditure over time, rather than energy expenditure during and immediately following exercise.

General Criticism of Published Studies on SuperSlow

Both the Westcott and Keeler studies were of insufficient duration to rule out motor learning as a significant factor in improved test performance. Clinical studies on exercise should last significantly longer than six to eight weeks, generally considered the duration over which motor learning has a significant effect on performance improvements.

Static strength testing protocols should be used in any study comparing the effects of repetition speeds for standardization and to rule out potential speed-specific improvements as a factor in test performance.

Some claim the results of these studies are questionable because subjects were not trained by certified SuperSlow instructors. However, the purpose of these studies was to compare exercise protocols, not instructional ability, and had certified SuperSlow instructors also trained the subjects in the traditional training groups their results would have also been better.

Force Gauge Experiments

Advocates claim SuperSlow strength training is safer than traditional, faster repetition protocols because it exposes the body to lower levels of force. However, force gauge experiments by Brian Johnston have shown no significant difference in peak forces during seated cable shoulder presses using 10/10, 5/5, or 2/4 repetition speeds.

Using a Quantrol AFTI digital force gauge and WinWedge software to plot data points, Johnston measured the forces during one repetition of cable shoulder presses using a resistance of 34 pounds, including the weight of the force gauge hardware and cable handle. The subject positioned himself at the end point of the range of motion then performed the negative and positive phases of the exercise using 10 second negative and positive movements, 5 second negative and positive movements, and 4 second negative and 2 second positive movements. Both the 10/10 and 5/5 protocols resulted in peak force measurements of 34.7 pounds. The 2/4 protocol only produced a slightly higher peak force measurement of 36.3 pounds. Although there was no significant difference between the 10/10, 5/5, and 2/4, all of these produced significantly lower peak forces than the "explosive" protocols tested, which resulted in measurements of 54.3 and 63.1 pounds.

The graph below shows the force gauge measurements of the 5/5 and SuperSlow 10/10 repetition speeds superimposed over the measurement of the traditional Nautilus 2/4 repetition speed. The width of the lines from the original 5/5 and 10/10 graphs have been adjusted so the start and end points line up with those of the 2/4 graph, but the heights of the lines has not been changed. Although the 2/4 line is easily identifiable due to the different ratio of time spent performing the negative to the positive, the measurements for the 5/5 and SuperSlow 10/10 repetition speeds are nearly impossible to tell apart.

Since the greatest acceleration typically occurs during the reversal of direction (turnaround) at the start and end of the range of motion rather than during the concentric or eccentric portion of an exercise, peak forces are affected significantly more by turnaround performance than repetition speed.

Although no significant reduction in peak force may be achieved by using repetition speeds slower than 5/5, slower repetition speeds may be safer for some trainees due to improved ability to maintain proper form and greater ease of observation and correction of form discrepancies by instructors. Individuals with poor kinesthetic sense or "body awareness" may also find it easier to focus on the target musculature when moving more slowly during exercise.

Conclusions

The application of SuperSlow current research shows to be most effective specifies a TTF of approximately 56 to 84 seconds and routines consisting of 13 exercises performed 2 to 3 times per week. Although the optimal workout volume and frequency varies between individuals, my experience, as well as the results of several surveys and informal experiments, have all confirmed SuperSlow stimulates the greatest increases in muscular hypertrophy when performed using resistance and set durations similar to the traditional Nautilus protocol.

Ken Hutchins, the developer of the SuperSlow protocol, and the SuperSlow Zone personal training franchise, currently recommend a TTF of 100 to 180 seconds and routines consisting of as few as 3 or 4 exercises performed 1 or 2 times per week. These recommendations are not supported by any research.

When using the SuperSlow exercise protocol the weight used for each exercise should only be reduced by approximately 20 to 30 percent initially, for learning purposes. Once proficiency has been obtained, the resistance should be gradually increased until muscular failure is achieved within 40 to 80 seconds, or two to four 10/10 repetitions.