Review: The effect of increasing loading on powerlifting movement form during the squat and deadlift
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Powerlifting often gets a bad reputation as a high-risk injury sport, but more recent studies have assessed powerlifting as low to moderate risk of injury. The highest risk for injury seems to be among lower level athletes, and injury risk includes both acute and chronic complaints. Between 33-47% of injuries studied are lower back injuries and approximately 30% are shoulder injuries. Lumbar injuries are thought to be a consequence of the extreme compressive and shear forces placed on the spine during the squat and deadlift. With weight lifted sometimes exceeding up to five times the lifter’s bodyweight, it is imperative that proper technique is used--using incorrect form exacerbates the effect of these forces on the lifter’s body.
Many of the injuries incurred in powerlifting are a result of posterior chain dysfunction, resulting in exaggerated lumbar or thoracic kyphosis. This positioning can deactivate the larger lumbar musculature, resulting in myoelectrical silence. Myoelectrical silence distributes excessive stress to the spinal ligaments, neural arch, disks, and facet joints of the lumbar spine. The knees may also be injured by increased moment arms on the knee joint, or by valgus collapse harming the ligaments that stabilize the knee. Imbalances in muscular strength or mobility often result in rotational movements at the torso, predisposing those athletes to injury. As correct form disperses compressive forces throughout the joints and reduces injury risk, it makes sense that using it should be a priority for lifters.
Training for powerlifting often includes very competition specific training, mean that lifters typically perform large amounts of training volume on the same competitive exercises. Any technical concerns are repeated at high frequency under increasing loads.
The purpose of the reviewed study was to examine the effect of increasing loading on technique during the squat and deadlift exercises. The researchers sought to determine if technical breakdowns occur at a certain percentage of lifters’ maximum capability and whether or not that threshold is correlated to athlete level. The study hoped to determine an upper ceiling of training percentages to inform coaching and training practices.
For this study, athletes were filmed on squats and deadlifts during one peaking session of their training cycle. The researchers chose a session designed to mimic a competition, and the athletes were loaded in incremental volumes until they reached their maximum weight (with rest between sets). The athletes were recorded in their normal training setting. Researchers analyzed lifts that would be considered successful in a competition for form and/or technique, comparing between loads and between individual subjects.
Six strength sport athletes made up the group of participants between 20 and 27 years of age, with a body mass between 83 and 144kgs. Athletes had completed at least two years of powerlifting-style resistance training and current powerlifting competitors. These lifters also held a minimum of a Bachelors level degree in Sports Science.
Subjects were recorded via digital video camera placed approximately 3 meters away, set on a tripod corresponding to the subject's center of mass. The camera was set in the transverse plane s