Post 39: Sprint Training

          As if anyone cares, I wrote an article back in February of last year on Speed Training. I always find it comforting when I can look back on things that I knew in the past... and realize I've learned since then. Recently I've been reading the eBook from Bret Contreras and Chris Beardsley, The Optimal Athlete: Sprinting. Although not everything I've read so far is exactly news to me, they've done a nice job of selecting studies to review that make more sense of what are sometimes abstract concepts.

          In the beginning, Bret makes a statement regarding the nature of scientific research. If you know anything about Contreras, you know he loves science. I would agree that sometimes it is frustrating to read studies that always end with "more research is needed," but as Bret mentions in the beginning of this review, it is wisest to stick to the common threads throughout the research.

          Since this blog is really more of a place for me to keep all my thoughts and stuff, I'm going to throw down a few things that I found to be of particular interest. Especially relevant to training athletes (most specifically sprinters) for speed. If that helps you great, if not, whatever.



Concept 1: Net horizontal propulsive forces are of greater importance than total ground reactive forces (including vertical.)

          A while back I recall reading an interview in which Bret talks about this French kid Christophe Lemaitre. In the interview, it was discussed that he tested with unusually high horizontally-oriented GRF's (ground reactive forces.)

          For those of you who are not familiar with the terminology, GRF's are the resulting force from the ground to the object in contact with it. For every action there is an equal and opposite reaction, etc. Therefore the GRF is equal to the force applied to the ground, and by virtue of the mechanics, it has a vector too.


          So in order for two things to happen: a) A human to travel forwards, b) A human to continue forward, force must be applied by the support leg both horizontally (to accomplish part a) and vertically to buy time for the trail leg to recover and enter the late swing phase before contact. What is interesting however, is that not only is it important to be able to apply a great deal of force quickly, but that the studies consistently demonstrate greater importance of the amount of force applied horizontally. Vertical GRF's are really only necessary to give the athlete time to prepare the subsequent stride and replace the next step in optimal location on the track. So with this in mind, coupled with specificity, it is recommended by the authors that sprinters use exercises which train strength and power in a more horizontal plane - Like Bret's famous Hip Thrusts.

Concept 2: F-V qualities of muscle are of greater importance than absolute strength.

          The Force-Velocity relationship is basically an illustration demonstrating that we move heavy weights slow and light weights fast. More specifically, different qualities fall on different parts of the force velocity cuve. As their names might suggest, Absolute Strength would fall far to the right, where load is greatest and speed is negligible, and speed-strength would fall high-left where muscle shortening velocity is highest, and load lowest. However, if you note the dotted line (as always) there is an optimal range for power output.

          Think about bench pressing. If you can take 135 pounds and throw it off your chest, doing reps will be fast, but not require a high percentage of your absolute strength. If you can take 300 pounds and move it slowly, you have likely taxed your absolute strength, but have not even begun to approach appreciable velocity. So although different for everyone, there is an optimal range for power output where the force produced and the velocity at which the muscle contracts to do so are in perfect balance. This gives you the greatest value for Power (Force / Time.) If we maximize both factors, we get the greatest product.

          Having said all that, consider that foot-to-ground contact times in sprinting are easily under a second in duration. I think I recall Louie Simmons writing that maximal contractions cannot be achieved before 0.4 seconds, so the ability to produce a LOT of force FAST is of paramount importance.

Concept 3: Vertical and joint stiffness. 

          As I believe I've mentioned before, energy leaks in the kinetic chain (although abstract in notion) are a very real thing. You miss lifts when you let your air out, good morning a back squat, or generally don't "stay tight" because you've allowed an energy leak. Force is best transferred through rigid segments, this includes everything from the forearm, to the trunk, to the core, to the femur and lower leg. This is best and most memorably demonstrated through the old "ever try to push a rope?" trick. Now that we've discussed desirable muscular contractile qualities, and the direction in which we should apply force, I'm going to say how it's best transferred to the track. If your body can produce these forces, you would be remiss to not effectively transfer the greatest possible percentage of them to the external environment.

          Stiffness as defined by the ability of an object to resist deformation when encountering forces, is important for sprinters. Generation of adequate force is the responsibility of the hip extensors and knee flexors, among other things. Transfer of force from body to ground involves some stiffening of the ankle, knee, hip and even trunk.

          Nothing operates at 100% efficiency, and the body is no exception, both mechanically and metabolically. If a sprinter is already limited by the amount of time (sub 1s.) to apply force to the track, and additionally by his or her own genetic capacity to produce force quickly via muscular contraction, it seems unfair that we lose even more energy/force when it can be dissipated by hypermobile joints.

There are a few thoughts for today.

Alex