Shannon Bowles is a graduate student in nutritional biochemistry and metabolism at the Friedman School. She has a BS in exercise science and psychology from the University of Utah. Shannon is certified strength and conditioning specialist and a former member of the U.S. National Gymnastics Team.
Super-slow resistance training is drawing attention as an effective means of gaining strength and losing weight. In 1982, Ken Hutchins developed the super-slow method out of a safety concern while working with osteoporotic patients and it soon progressed into one of the many resistance training techniques promoted today. While promotion of the super-slow technique lives on, so does the controversy over its efficacy.
In a world where more is perceived as better, how can super "slow" translate into super "gain"?
The formula: four to six repetitions consisting of a 10 second concentric phase (the phase in which a muscle is shortening, as in the upward movement of a biceps curl) and a four to 10 second eccentric phase (the phase in which a muscle is lengthening, as in the downward movement of a biceps curl). The benefit: less momentum is involved in the lift, forcing the muscle to work harder. The downfall: it's tough and tedious. The secret: increased tension on the muscle of interest.
The theory behind slower speed lifting is that it requires increased muscle fiber activation and firing frequency to maintain lifting a load for a prolonged period of time. This stimulates significant muscle strength development. The first adaptation is neurological (improved rate of firing and greater recruitment of muscle fibers) and the second is an increase in muscle size.
While the premise may sound promising, critics are leery of the lack of evidence to support the proposed claims.
According to advocates, super-slow resistance training improves muscular strength, aerobic fitness, sport performance and general functionality in a safer and superior manner than traditional methods of cardiovascular or resistance training. Proponents argue that benefits are obtainable with a mere 15- to 30-minute workout per week. What's the old saying? "If it sounds too good to be true, it probably is."
Although low-velocity lifting has increased in popularity over the last decade, only one peer-reviewed study has indicated potential superiority over traditional techniques at improving strength.
In 1993 and 1999 Wayne Westcott, a fitness research director at they YMCA in Quincy, Mass. compared men and women utilizing the super slow regimen to those utilizing a normal speed regimen over a two month period.
Subjects in the super-slow group displayed a 50 percent greater strength gain on most exercises compared to the regular speed lifters, the study concluded. However, critics were quick to harp on the method of testing: a 10 repetition maximum (10RM) protocol was used for the normal speed group and a five RM was used for the super-slow group.
Many fitness gurus contend that a 10 RM is a poor measure of strength and second; it is difficult to compare between group improvements when 10 RM was used in one group, while five RM was used in the other.
Another study compared a small group of untrained women over a 10-week period and found conflicting results. Both the super slow group and traditional speed group trained three days per week and completed one set of eight to 12 repetitions on eight exercises. After one RM testing at the end of the study the traditional group showed more improvement in five of the eight exercises and in total weight lifted compared to the low-velocity group (39 percent compared to 15 percent respectively).
A few studies have failed to find cardiorespiratory benefits of super slow lifting. It has also been demonstrated that super slow techniques result in less metabolic stimulus, less lean body mass gain, and fewer expended calories in comparison to traditional methods.
The greatest strength improvements from resistance exercise seem to be at speeds performed during maximal exertion. In terms of athletic performance, many sport movements are carried out at high velocities. Studies specifically designed to look at super slow training and athletic gain are scant, but it appears to be an unlikely match with the possible exception of athletes who compete in slow motion.
The proposed safety benefit of low-velocity resistance training has not been formally studied either. The belief is that without ballistic movements there is less risk for injury. However, when a ballistic type strength program is properly supervised the risk of injury is very low. It has been suggested that super slow training may even add risk due to the degree of tension applied over a long time period to the muscle and tendon.
The bottom line is that research on the benefits or downfalls of super-slow resistance exercise is limited. Until further well-designed studies provide necessary evidence to fill the gaps in knowledge, recommending the super slow technique remains difficult. While the current rise in its promotion appears unsupported by research at this point, super-slow resistance training may one day find its place in a particular ring of the fitness arena.
