Why should we be limited by arbitrary guidelines like a 10% load or a 10% decrease in speed. Over twenty yards, ten percent is 2 one-hundreths of a second. The key should be to look at the athletes posture and motor pattern.
I am glad that Coach Boyle reprinted his earlier article. After reading it the first time, I had some counter points but we must always rethink conventional wisdom. I am glad he questions the past, as we need to not be trapped by dogma. 10% is not a law but a suggestion that seems to have merit, and I think both sides of the argument should be shared. Coach Boyle questions conventional wisdom and has helped the strength and conditioning field with a lot of valid arguments to think differently. Being a fellow mac guy, thinking different is very helpful, but differences must have reasons why they are better options. I just prefer to use sleds differently than he does, and more conventional with loading parameters. Perhaps the math he shared altered his perception and would change his mind if he looked at the numbers again? If he knew 2 one-hundreths of a second is not 10%, would he change his mind? We all make mistakes but 10% is two tenths or more, not .02. Similar to the reasons why people like scoring the body between 0-3, we need to look at the fuzzy math a little more and see what is lost in translation.
Mike has a good blog and his article on Sled Training brings up some very important details such as the difference between acceleration and top speed. One odd note was the use of the term hip hyperextension, something I don’t see at all in acceleration, especially with pushing heavy sleds. While the foot may pass the center of mass, the line from the ankle to the ear is straight, anything beyond that has little to no contribution in acceleration period. In fact at top speed front side mechanics are valuable to set up hip extension during the late phase of ground support, as this is irrefutable with research and video.
Another aspect of the article in question, was the use of very heavy loads to create a bridge between conventional lifts and sprinting. While I think it’s good for a fullback or lineman to be exposed to that for games requiring such activities, this isn’t going to be the missing link by any way with athletes trying to maximize acceleration. In the video, the athlete was getting into severe ankle drop, destroying the valuable forefoot stiffness that we need to accelerate. Athletes, even elites, struggle to have enough rapid ankle stiffness, this is why a 10% load is often suggested, otherwise we get lost in a limbo of too slow for speed, and draining the body from aspects like heavy squatting and olympic lifts. The overload is not going to slow you down, but being a prime variable in developing speed in a complete program isn’t researched or even historically showing an impact in the NFL combines. When I see 4.2s by legions of athletes doing so because of prowlers or heavy sleds, I will drink the kool-aid from the goblet squat. While the world strongest man may be able to pull semi trucks, the worlds FASTEST man is average in strength compare to NFL receivers, yet is able to accelerate with the best of them for 10-20 meters before embarrassing them.
If you wish to work on acceleration and the use of a loaded sled, the two variables I care about are mechanics, and speed. With a finite amount of time working with athletes and working on movement quality, actual sprinting is a must. Elite sprinters have gone beyond 10% and sometimes up to 20-30%, but never to the point it looks like the call of the wild. When load decays those qualities statistically to the point it’s significant I decrease the weight and focus on getting faster, not heavier. Coaching is about teaching, not how many plates you can put on a sled. I love maximal performances and follow all of the strength sports, but save the plates for the squat rack and platforms.