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Bryan Mann1,2, Josh Stoner2 & Pat Ivey2

1Department of Physical Therapy and Athletic Training, 2Athletics Performance Department, University of Missouri, Columbia, Missouri

PURPOSE: The back squat has been considered the gold standard for lower body strengthening in college football for many years. However, due to disc injury, many athletes are unable to perform this exercise as the axial loading exacerbates their symptoms. Many athletes have been relegated to machines such as leg press, leg extension, leg curl in attempt to maintain or prevent loss of strength to the legs, but rarely do they have a very high transfer of training due to the nature of requiring no stabilization. This intervention was an attempt to see what the effect of replacing the back squat with a heavy sled pull in terms of improvement in speed development in an individual with disc herniation currently experiencing back pain.

METHODS: The subject for this study was an NCAA Division 1 quarterback with disc herniation at L5-S1 and L4-L5. Instead of performing the barbell back squat, the athlete performed sled pulls with a sled that had the ability to add weight to it. The athlete pulled the sled in a walking manner. The athlete was not allowed to run at any point with the sled. The forward lean angle of the athlete was self-determined. The athlete pulled the sled for 8 repetitions of 27.4 meters every week for 6 weeks. The first week, the athlete started with their bodyweight on the sled, approximately 90kg. For every subsequent set, the weight was altered based off of RPE. The desired RPE was an 8, if the RPE was higher, the weight was reduced. If the RPE was lower than 8, the weight was increased. The 39.6m sprint test was done in a pre/post-test design at week 1 and week 6 to assess sprinting speed.

RESULTS: Over the course of the six weeks, the load on the sled increased from 90kg to 380kg. The mean change in the 39.6m sprint for the entire football team during this period was .02 seconds. The change of the athlete who performed the sled pull was an improvement of .26 seconds. Interestingly, the subject also self-reported being able to throw the ball with greater velocity due to the improved leg strength from pulling the sled; this is important due to his position as a quarterback.

CONCLUSION: The individual who pulled the sled showed a marked increase of strength in this movement, improving strength by 422% in this movement. While neurological adaptations most likely played a major role in this increase, the training effect cannot be discounted. The individual improved their speed significantly, not only for an individual significant improvement, but greater than the team improvement. It is possible that the improvement in running speed is a transfer of trainedness effect due to the fact that the force was being produced horizontally rather than vertically, and other individuals would see similar improvements.

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