TweetDeceleration Mechanics: A Lost Art


No, I am not talking about the grease monkey at your local garage who just FUBAR’ed your brake job and now your car sounds like it’s grinding steel on steel as you approach a red light. I am writing this article because my experience of late has shown that the ability of my athletes to decelerate their body weight, then use that potential energy and translate it back into kinetic energy accelerating out of a jump or turn has been lost. This problem is something that I have had to address with the high prevalence of ACL injuries especially within my female population.

First a little background, the sports with the highest occurrence of ACL injuries for female athletes are in order gymnastics, soccer, basketball, field hockey, volleyball, lacrosse, and then softball. For men, it is close between football and wrestling. According to the 1999 article by M.L. Ireland women are 2 to 8 times more likely to have an injury than men. You may be asking why? The answer is comprised of a multitude of intrinsic factors such as “hormonal influences, intercondylar notch width, joint laxity, limb alignment, muscle strength, neuromuscular activation, ligament size and extrinsic factors such as excessive shoe-surface interface friction, sports activity, training/conditioning level and equipment (4).” With all these variables the ones we as strength and conditioning coaches can control the best for our male and female athletes are lower limb alignment, muscle strength, neuromuscular activation and training/conditioning level. I will come back to this later but let’s just look at what typically happens when the ACL tears.

“Commonly, the athlete runs, suddenly stops, and then turns, thereby causing a deceleration of the lower limb, a forced hyperextension of the knee, or a forced tibial rotation, resulting in injury to the ACL (3).” What I see typically with my athletes is when jumping they land on the balls of their feet and end up with their knees out over their toes, then jump back up. This lends to the majority of the work concentrated on the quads and not letting their hamstrings, glutes and hips take the majority of the impact force. In simplest terms they don’t sit back when landing, and that leads to big problems down the road. “It is the synergistic relationship between the ACL and the hamstrings that activates to decrease the shear forces at the knee during pivoting and jumping motions (5).” “In contrast, the quadriceps acts antagonistically to the ACL, encouraging forward displacement of the tibia relative to the femur. The contraction force produced by the quadriceps can produce forces in excess of what the ligament can handle, predisposing a person to ligament tensile failure (1).” These facts elucidate the two most prevalent problems I see with my athletes when they enter the program. The first is posterior chain deficiencies in athletes are so common that I have come to just expect it and know that it will be a priority in their training program. And second is poor jumping/deceleration mechanics.

By addressing these problems we can lower the injury rate and keep your athletes on the field and out of the athletic training room. In doing so, you make yourself invaluable to your sport coaches and look like a damn genius to your AD! Let’s come back to those factors mentioned earlier that we can control. First, lower limb alignment can be worked on every time you squat, deadlift, lunge, clean, snatch or jerk. Remember that the key is to tell your athletes to let your hips, hamstrings and glutes do the work. I always ask my athletes which joint can hold more weight, the hip or the knee? They always answer the hip and then I say, “Then why don’t you use the damn things?”

Make sure that during squats they have proper foot placement and on the concentric portion there is no valgus stress on the knee. With lunges, step-ups, Bulgarian split squats or any other unilateral movement the key is to watch the knee angle. To be safe I am always saying I want a 90 degree angle at the back of the knee with the top of the thigh parallel in the bottom. If I don’t see it, my athletes go right back to body weight only until they get it right. There is nothing wrong with backing an athlete off until they get it right. It will pay huge dividends in the future and save you a lot of headaches. With the O-lifts the key is to watch the catch in whatever lift you might be performing. They must catch everything with their heels down and their feet the proper width or you are setting them up for problems. I absolutely lose my mind when I see one of my athletes catch in a jump jack stance on their toes when doing a clean. Remember if you use the O-lifts the primary goal is to increase rate of force development and power output not coordination. Coordination is a nice by-product but not the primary reason for using them. So, if they can’t do it right then take them back to explosive pulls and they will still make tremendous progress.

Second, muscle strength should be a no brainer if you are a reader of this website. Like I said before, the posterior chain usually needs to be brought up to speed. I have all my athletes able to tell me the phrase I was taught a long time ago by one of my mentors Jason Beaulieu at the University of Delaware. “The show muscles are in the front and the go muscles are in the back!” A steady diet of Romanian deadlifts (RDL), glute ham raises, good mornings, deadlifts and Reverse Hyperextensions will cure that problem in no time. I am also a huge fan, albeit to the displeasure of my athletes, of iso-dumbell and barbell RDLs and iso-hamstring bridges for time. If you haven’t tried them, give them a shot, but be ready for problems walking for the next few days. The bonuses of these movements are a ton of stabilizer activation and proprioception work.

Third, neuromuscular activation speaks toward proper jumping, landing and turning mechanics. “Bouncing” not “sticking” is where it’s at and if that sounds familiar good, you probably know who it came from. “During natural movements, the primary requirement for a proper motion pattern is not to resist the external force and decrease the body’s kinetic energy but to increase the potential for the ensuing takeoff (Zatsiorsky, 158.)” When it comes to jumping and landing you want your athletes to focus on landing “soft” and making as little sound as possible. “During soft landing by experienced athletes, only 0.5% of the body’s kinetic energy is spent to deform body tissues (bone, cartilage, spine). During a stiff landing, the deformation energy amounts to 75% of the body’s mechanical energy. The difference is 150 fold! (Zatsiorsky, 178)” I like to use box jumps a lot for practicing soft landings before I incorporate traditional plyometrics. I tell my athletes I am looking for a Neo from The Matrix type landing because when its done right that’s what it looks like. You look like you are floating and you set yourself down on the box and absorb the impact by sitting back and letting the hamstrings/posterior chain do the work. The less noise made on impact the better the jump.

You also want to make your athletes good at getting in and out of turns as fast and as efficiently as possible. This is a tenet of training reiterated to me by Jeff Conners at the University of North Carolina and Dwight Galt at the University of Maryland that holds true no matter what the sport. If an athlete can turn quickly and change direction without dissipating a lot of energy they tend to be successful on the field. Teaching turns is all about fluidity. I like to use that word because my athletes get a mental picture of smooth, flowing movements. I tell them the idea is to lose as little speed as possible when turning. There are entire books dedicated to agilities, running mechanics and turning so I won’t attempt to go into detail because I wouldn’t do it justice in this brief article. The focus here is to remember that the keys to turning and reducing the risk of knee injury are to have the athlete get use to firing the hamstrings first and not the quadriceps to decelerate themselves. This is accomplished by touching the ground with legs extended and feet plantar-flexed, and immediately after ground contact, avoid a stiff landing by flexing the knees and lowering their center of gravity (Zatsiorsky, 178). Another good mental image I use with my athletes is to think of a spring that compresses then explodes.

Fourth, training/conditioning level is vital as the contest progresses. It’s easy to stop by landing on your toes when fatigue begins to set in. It’s just natural that your athletes will go to the old, easy default setting if they are not conditioned to use the proper mechanics all the time. What I have found to work best for this is variations of the repetition method. Using a light weight for sets of 30, 40 and 50 in all forms of the squat or deadlift are not easy but elicit the ability to fire the proper motor pattern repeatedly. Remember you are looking for the athlete to perform these actions without conscious thought and acquire muscle memory. With these you are only limited by your imagination.

When it comes to working on change of direction I found that a continuous pattern where you can run a lot of athletes through at once works the best. I tell my athletes that we play in 3-D so we will train in all planes and directions of movement. Snake, zig-zag, or wheel patterns and shuttles are ideal. Once again these are only a few examples and you are only limited by your imagination. The key is to stress proper turning mechanics even when fatigue starts to take hold. The bonus to this type of pattern is energy system development. This continuous pattern running closely simulates most court and field sports metabolic demands as compared to straight ahead speed and distance runs. Not that they don’t have their place in an athletes training but they should not be the end all be all.

If I hear one more sport coach tell me their athletes’ mile time I will have to pull out my wakizashi and commit seppuku and gut myself like a trout, but at least I will die honorably! If they aren’t on the track or x-country team I don’t care! How about, can they run 15-17 100 yd sprints all out with a minute rest in between without a significant drop off in time? If that doesn’t sound difficult try it and your heart and lungs might jump out of your chest and kick your own ass! If they don’t, then I take my hat off to you and you’re in tremendous shape.

In summary, I feel that as strength professionals if we can focus a little more on limb alignment, muscular strength, neuromuscular activation and conditioning this will help alleviate the rampant problem of knee/ACL injuries we see in athletics today. We all know that it isn’t completely unavoidable and injuries will occur but by reducing injury rates and decreasing recovery times we will make a stronger, more durable, more productive athlete for the future.

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