Removing Stretch-Shortening Cycle Doesn't Negatively Affect Muscle Activity, Reports The Journal of Strength and Conditioning Research
Newswise — The "box squat", a popular training technique for weightlifters, has "limited negative consequences" on squat performance during strength training, reports a study in the December issue of The Journal of Strength and Conditioning Research, official research journal of the National Strength and Conditioning Association. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, and pharmacy.
"This study found very little difference in kinetic variables or muscle activity between the two lifts," according to the study, led by Jeffrey M. McBride of Appalachian State University, Boone, N.C. "Thus, the use of a squat or box squat provides a very similar stimulus to the leg and lower back musculature and therefore would most likely result in a similar amount of strength gain with training." 'Box' Technique Removes Stretch-Shortening Cycle, But Doesn't Decrease Squat PowerIn the standard squat technique, the weightlifter positions the barbell across the upper back, then lowers the knees to reach a squatting position. The box squat is a simple modification of this technique in which the lifter stops and sits on a box at the end of the squat. That means the box squat consists of an eccentric phase only—it eliminates the concentric phase, or "stretch-shortening" cycle, at the end of the squat.
To test the effects of this modified technique, the researchers had eight competitive male powerlifters perform a series of squats and box squats in random order. The movements were done while standing on a force platform with transducers attached to the bar to measure force and velocity, which were used to calculate power. Electromyography was used to measure electrical activity in the relevant muscles.
"Results indicate that peak force and peak power are similar between the squat and box squat," McBride and colleagues write. In fact, during some repetitions, peak force was significantly lower during the squat, compared to the box squat. In general, electromyography showed higher muscle activity during the squat, compared to the box squat.
The box squat is a popular alternative to the conventional squat technique for weightlifters. However, the use of a box eliminates the stretch-shortening cycle. In other types of activities—especially jumping, a stretch-shortening cycle results in significantly increased performance. However, no previous studies have looked at how removing the stretch-shortening cycle by using a box affects the kinetics and muscle activity of the lift.
The results suggest that the box squat "has neither a significant positive or negative effect on squat performance," the authors write. "Thus the use of a squat or box squat provides a very similar stimulus to the leg and lower back musculature and would most likely result in a similar amount of strength gain with training." However, they believe that since a stretch-shortening cycle is a "vital component" of most sports, "a squat including a stretch-shortening cycle may be of greater benefit."
About The Journal of Strength and Conditioning ResearchThe editorial mission of The Journal of Strength and Conditioning Research (JSCR) is to advance the knowledge about strength and conditioning through research. A unique aspect of this journal is that it includes recommendations for the practical use of research findings. While the journal name identifies strength and conditioning as separate entities, strength is considered a part of conditioning. The journal wishes to promote the publication of peer-reviewed manuscripts which add to our understanding of conditioning and sport through applied exercise science. The JSCR is the official research journal of the National Strength and Conditioning Association. National Strength and Conditioning Association.
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