Elitetrack: Sport Training & Conditioning

Jeremy Richmond - 01 April 2008 10:16 AM

I’m not exactly sure how the continuous fast leg drill goes on the track but the cycling of the leg is an unloaded movement to the complete range of motion of sprinting. The objective is to use a stopwatch to encourage the athlete to move the leg faster in both phases. Almasbakk & Hoff (1996) determined that velocity improvement is the result of an improvement in coordination and Schneider (1989) showed changes to the pattern of neural recruitment of muscle as a result of rapid movements. If the athlete achieves an improvement in movement velocity of the leg, it could be the result of synchronous firing of motor units, earlier recruitment of fast twitch muscle fibre or reduced inhibition of the antagonist muscle. Ultimately, the objective is to increase the back-swing velocity of the leg which will increase the momentum of the leg (Momentum= mass x velocity) to the benefit of force production on impact with the ground. If an improvement is made to the forward swing velocity of the leg, a sling-shot effect could eventuate from the rapid transition from forward to backward swing. For the benefits of this aspect to be realised, we will have to wait until the connective tissues in the tendons of the upper leg/ glutes can adapt which takes a few weeks. Too much information?

No problem.  When you discuss the back swing velocity, are you referring to the action from when the swing foot is directly under the center of mass and rotating up under the glute and passing over the support knee?  An action similar to this: http://youtube.com/watch?v=D69FKic2zL0

I do realize your procedure requires continuous repetition of a cycling pattern that one might recall from Speed Dynamics fast claw action.

Thanks for the follow-up.

Good find thanks for that. I would imagine the exercise is the same. The thigh starts parallel to the ground, swings down to perpendicular and then back up to parallel and the cycle begins again. The foot passes behind the body and up (and over) towards the glute as the legs swings up. Same principle as the fast claw (motor behaviour) except that by timing the movement, the human athlete cannot resist going faster next time.

In terms of back swing velocity, I am referring to the thigh velocity mainly as we are attempting to match or better that in the study by Kivi 2001, of 666 degrees per second at 9.9 m/s. In addition, any improvement to angular velocity of the thigh would also be leveraged into increased velocity of the foot prior to impact.

Still playing devil’s advocate here….
How can we expect to time angular velocities to an accuracy anything higher than a m/s (i.e. 9m/s or 10m/s and not 9.34 m/s) when we aren’t really measuring thigh angular displacement and are timing with a method (hand time) that is known to be only accurate to the tenth of a second. Also, how do we account for the temptation to cheat the ROM to attain higher and higher angular velocities? Finally, what would you say to the idea that very fast hip extension (the component that this exercise focuses on) is of little value and possibly detrimental if the athlete lacks the leg stiffness to handle impact forces at ground contact.

Debate is good. Probably need a bit more clarity. Kivi 2001 measured thigh/hip extension angular velocity of 666 degrees per second whilst running at 9.9 m/s. We are estimating the angular velocity of the thigh whilst standing stationary when doing the exercise. Whether any improvement in the exercise will transfer into actual improvement in sprinting is a good question. If we increase the velocity of the leg by 10% thus increasing the momentum by 10% assuming the position of the different parts of the leg remain the same with the increase in speed, we would expect some loss but not all of the energy at impact. Therefore it would still represent an increase in energy transfer. In addition, by imposing demands on the leg at the presumed increase in velocity if doing sprint training concurrently, we would expect some adaptation. By exposing the leg to a velocity specific resistance stimulus when running (with the new increase in velocity of the leg) the adaptations may occur to both the muscle and tendons/connective tissue.
Of course this is presuming an increase in thigh/hip extension velocity as a result of the exercise. Unfortunately, humans will attempt to cheat the exercise by reducing range of motion and even reducing the count. Hopefully that is where the coach would come into play.
Here’s a question. How much loss of energy at impact do current methods of training prevent especially over and above sprint running alone?

How might you be able to calculate angular velocity from video of sprint sessions?

To do it with any accuracy would be nearly impossible without a 3D DLT transform, a high speed camera (>200 fps) and digitized video. If you didn’t care about accuracy then you could use some basic motion analysis software (like Silicone Coach or Dartfish), align the camera perfectly in the sagital plane of the runner and then figure out how many degrees the thigh moved (preferably using some form of landmarks on the athletes body at the hip and knee joints) when he passed the camera and then divide that by the time it too to move through that range of motion.  I would guess that you could get errors as great as 50 degrees / second like that though which would make it pretty worthless.

Mike Young - 03 April 2008 07:29 AM

To do it with any accuracy would be nearly impossible without a 3D DLT transform, a high speed camera (>200 fps) and digitized video. If you didn’t care about accuracy then you could use some basic motion analysis software (like Silicone Coach or Dartfish), align the camera perfectly in the sagital plane of the runner and then figure out how many degrees the thigh moved (preferably using some form of landmarks on the athletes body at the hip and knee joints) when he passed the camera and then divide that by the time it too to move through that range of motion.  I would guess that you could get errors as great as 50 degrees / second like that though which would make it pretty worthless.

Thanks Mike.  Software not a problem. Camera and DLT are another matter altogether.  I might go through the process, although realizing that the end result might be unusuable.

Please keep us posted on both the analysis side and your opinions on the efficacy of the protocol.

Mike Young - 08 April 2008 09:12 PM

Please keep us posted on both the analysis side and your opinions on the efficacy of the protocol.

I will.  I have 2 groups that either have begun some work in this area and another to start in a few weeks.  I expect this aspect of our program to continue into and throughout the summer.

I will tell you that I’m skeptical of the process and believe that more than the activities discussed will reflect improvement.  However, as an alternative for some of our young developmental athletes, I’m more than willing to implement.

By the way, do you see any correlation between the work discussed in this thread and the following presentation from Osaka:

Mid-phase sprinting movements of Tyson Gay and Asafa Powell in the 100-m race during the 2007 IAAF World Championships in Athletics
Akira Ito, Koji Fukuda and Kota Kijima Osaka University of Health and Sport Sciences, Osaka, Japan

Abstract
In the present study, the running movements of Tyson Gay (9.85 seconds) and Asafa Powell (9.96 seconds) who finished first and third, respectively, in the 2007 IAAF World Championships in Athletics were analyzed. Their data were compared to past data (Ito et al., 1998) in order to determine the characteristics of both sprinters.  Maximal sprint running velocity was 11.85 m/s for Gay and 11.88 m/s for Powell. For Gay and Powell, step frequency was 4.90 and 4.96 steps/s, respectively, and step length was 2.42 and 2.40 m, respectively. According to Ito et al. (1998), sprint running velocity is not related to maximum thigh angle “high knee”, but the faster the sprint running velocity, the greater the minimum knee angle. The maximum thigh angle for Gay and Powell was comparable at 65° and 70°, and the minimum knee angle for Gay and Powell was 41° and 38°, respectively, and these numbers were similar to the data obtained by Ito et al. (1998). The horizontal distance from the toe at the point of landing to the center of gravity for the two sprinters was 0.31 m, and this number is comparable to that for sprinters who run 100 meters in 11 seconds (Fukuda and Ito, 2004). Therefore, it is not necessarily good to land immediately underneath the center of gravity when landing. In support leg movements, an interesting finding was seen with maximum knee extension velocity for Gay and Powell. During landing, the knee joint of both sprinters always remained bent, and when acceleration force was expressed during the latter half of the support phase, the extension velocity had a negative value: -50 degrees/s for Gay and -68 degrees/s for Powell.  Training guidance that attempts to increase sprint running velocity by reducing the deceleration associated with landing must be reexamined because the landing distance for Gay and Powell is comparable to that of sprinters who run 100 m in 11 seconds. What is important here is that Gay and Powell continue to bend the knee of the support leg during the support phase, and training guidance that instructs sprinters to actively extend the knee and ankle joints of the support leg must be reevaluated.

Protocol? Which protocol are you using? If you are trying to increase the rate at which you can cycle your leg, after an initial improvement to the rate you may encounter a plateau. I would suggest that when you get to that point, you add load to the movement with a little weight around the leg. An easy way to do this is to wear a boot such as an old army boot. The slight addition of load was shown by Almeida (1995) to improve the speed of an unloaded movement not to mention that it becomes a bit more specific as the leg encounters load in actual sprinting when it hits the ground. Once you hit the plateau, the (rapid dynamic training) protocol should then involve the use of slight load (bias) for some sets and no load for other sets of the leg cycling exercise.

Jeremy Richmond - 12 April 2008 10:17 AM

Protocol? Which protocol are you using? If you are trying to increase the rate at which you can cycle your leg, after an initial improvement to the rate you may encounter a plateau. I would suggest that when you get to that point, you add load to the movement with a little weight around the leg. An easy way to do this is to wear a boot such as an old army boot. The slight addition of load was shown by Almeida (1995) to improve the speed of an unloaded movement not to mention that it becomes a bit more specific as the leg encounters load in actual sprinting when it hits the ground. Once you hit the plateau, the (rapid dynamic training) protocol should then involve the use of slight load (bias) for some sets and no load for other sets of the leg cycling exercise.

Wearing leg weights can cause form to deteriorate.

With all due respect, I would never use leg weights or anything to that affect.  These are developmental athletes with very limited strength levels.  Where resistance is concerned, I have used bands or flexor apparatus.  However, its’ use will not be prominent.

They attributed this to a greater
average backswing acceleration of the thigh. If shorter
ground force production time is the mechanism that will
enable faster running speeds, then this must be achieved
through faster moving limbs either during or prior to the
foot making contact with the ground.

Mike Young - 31 March 2008 06:38 AM

Isn’t this primarily training the speed of the swing phase….something which Barry Ross says is completely and totally unimportant to sprinting speed. What would say to the argument that speed is completely generated at ground contact and not during the swing phase?

Wouldnt faster ground forces require greater ground forces not quicker leg swing.  Because even if you can bring your leg around quicker it doesnt necessarily mean you can produce greater ground forces.

Furthermore, greater thigh
acceleration results in shorter ground force production
time thereby reducing time on the ground.

Do you mean backward thigh acceleration(from a high knee position)?  Or back to front?

I was under the impression that it was fairly well documented that the best way to get faster is to increase stride length not frequency.

Question: “Is stride length the cause or the effect?“ The practice of leg cycling would increase the backward swing of the leg as well as the forward swing although a transfer to actual sprinting remains to be measured accurately. Forward swing is not as important but an increase surely would not harm sprinting. Backward swing is important. Derek Kivi (ISB XVII Congress Abstract 1999) reported the forward swing (hip flexion) of Donovan Bailey at 11.18 m/s to be 918 deg/sec and compared this to Chengzi’s (1987) result of 910 deg/sec for sprinters at 10.82 m/s. In contrast, Kivi reported Bailey’s hip extension to be 953 deg/sec compared to Chengzi’s study of 550 deg/sec. Furthermore, Derek Kivi describes the accelerated backward movement of the leg to be improving Bailey’s foot velocity and decreasing the braking forces at contact. The whole point of the article is that for faster movement of the propulsive limbs for sprinting beyond your current plateau’s, find a similar movement and practice that movement repetitively with a view to reducing the time to execute the movement. If (for example) you are currently taking 250 milliseconds to swing your thigh backwards at the moment, you may need to practice against less load until you reduce that swing-back time (thereby increasing the angular velocity)before increasing the load again. In order to facilitate the faster movement, a faster contraction of the muscle has to be the cause.

Let me spur some discussion…

Are we putting the cart before the horse here?  Is faster sprinting cause of faster leg cycling or greater downward forces (which in turn may make the leg cycle faster).