Barry Ross on Ben and Maurice!

Expert Discussion Advanced Sprint Training
361

In a post clinic response to the question of Rate of Swing/Swing Time, Weyand noted the following:

"Rate functions, by definition have time in the denominator. For example: Speed
is distance per time. One can convert a TIME taken to cover a known distance
into a RATE (rate of forward speed) simply by dividing the distance by the
measured time.

For limb swing rates, the correct expression would be 1/swing time. If the
swing times are the same, the swing rates, by mathematical necessity, are also
the same."

362

1/time is stride frequency, not rate. Rate, by definition is distance /time, as you state above. You cannot take out the distance component and say that you are still referring to ‘rate’. Stride rate and stride frequency are not the same.

But what we are discussing here misses the point. Stride frequency and SR are determined by what occurs during stance phase. SL in swing (air phase) is determined by muscle forces that are generated during the preceding stance phase. F runners have a greater SR because of shorger ground contact time during stance phase.

What occurs during double-legged air phase is not that important. It is the forces that the athlete generates during stance phase - that is what is important.

Single legged air phase is different.

The point is that the greater SR and greater SL for F runners is due to their ability to generate greater GRFs. The greater GRFs are due primarily to those forces in the vertical component. In addiiton, Horizontal forces are also important for generating and maintaining a maximal Peak Velocity in a sprint (@ 1/3rd as important as V forces). Finally, H forces are generated mostly by muscles that act at the hip (flexors and extensors)

The above statements are based on extensive analysis of the biomechanics of sprinting and numerous studies that corroborate those thoughts. Many disagree with the thoughts on the horizontal forces.

As far as Weyands study, my previous comments are based on average rate of movement for single-legged air phase, rather than double-legged air phase. BIG mistake. My mistake and am very sorry for my miscommunication generating confusion.

363

Can you amplify on how you feel coaching protocols will be affected? (I assume you mean training rather than technique)

364

It might have been my day, but, sadly, in amateur times, there was no “hey”.
Regardless of wind, there should be no technical change at top speed.

365

That is your opinion. There is no statement regarding maximal hip flexion and that is not the reason why more rapid leg movements were not determined to be a factor in increased running speed. You’re editorializing.

Next, I interpret that ‘more rapid leg movement’ means ‘rate’ doesn’t it. I mean if an object moves ‘rapidly’ we are talking about the rate (ie., How fast is it going? “rapidly”) that the object moves, aren’t we?
But the leg moves a greater distance (greater SL swing) in an equal time (equal air phase time of 0.l28). THis means that the AVERAGE rate of leg movement has to be greater. In other words, for F runners they reposition their legs (meaning repositioning the leg from one toe-touch to the next toe-touch) a greater distance (greater SL) in an equal period of time (0.0128 s)So the ratio SL/ time is greater, which is really the rate of movement. This is average rate of leg movement. (That is my point on rate.) .

Your point does not apply. There was a mean aerial time of 0.128s and the aerial times were spread non-linearly across the entire group. Swing times were slower at lower speed for faster runners, but all runners reached similar swing times at each runners top speed. The mean swing time was 0.373s. Your using an aerial mean time for your analysis of swing time. The leg doesn’t move a greater distance by necessity, the COM does.

I understand that the studies I quote are ‘old’. But it rather remarkable that the ratio of Horizontal (H) to V forces at peak velocity is @ 1/3rd for all of these studies. The point is that GRFs are increased in both the V and H plane at peak velocity.

What is remarkable is that the preponderance of studies today use an approximate ratio of 10-1 not 3-1. In order to prove your point, you dug up some studies (up to 40 years old), decide they fit your model better and therefore must be more accurate than more recent studies. You then build your case around that ratio as if it is the correct one. You’ve made so many errors in your analysis of the Weyand study that one might not want to accept your reporting of the other studies as accurate.

Total Forces (GRFs) are increased with greater running velocity. (WE all agree on that one.) They are increased because the same impulse that is created by F and S runners is generated in a shorter ground contact time (GCT) for F runners. For the F runner to be able to generate an equal impulse as a S runner, but to do so in a shorter time period requires that a greater force is applied.

Well, take me out of the “WE”. GRF’s are not increased with greater running velocity. Greater running speeds are caused by increasing GRF. Increasing GRF decreases GCT because of Newtons 3rd. Effective impulse is the product of GCT and ground support force applied to the running surface in opposition to gravity. The effect of similar impulses affected aerial times. The result was a mean aerial time of 0.128 as stated above.

The GRFs are greater in the horizontal plane because the impulse is generated in a much shorter time period than during acceleration phase. SO, yes, horizontal forces are greater in peak velocity than they are in acceleration phase of a sprint. (I believe that you are in disagreement with this statement)As far as vertical displacement. It is dependent on air phase time, so if air phase times are equal between F and S runners then vertical displacements are also equal.

I think i’m disagreement, but since I’m not sure I understand what you are saying I’m not sure I disagree. I guess. It does not necessarily follow that GRF’s are greater in the H plane because of the shortness of time for generation of effective impulses. I want to make sure we all understand that we’re talking about vector changes between the start and approaching max velocity. Greater amounts of H F would occur at the start than later in a race because of inertia and other factors. As the vector changes, the amount of force required to offset the effects of gravity causes the V to require increasingly greater amounts of force than H because gravity does not affect absolute H (which is why the 3-1 ratio makes little sense.)
Your use of impulse here is incorrect. Impulse is created by ground support force and GCT. Ground force support is necessitated by the force of gravity acting on the mass of the body, which can be 3-5 x bodyweight, and it can only apply in the vertical. Since GReactionF is the equal and opposite it would be 0 at absolute horizontal. We are not going to get away with suspending the laws of gravity or any of Newton’s laws because we are competing in a sport.

I’m not trying to be mean here, but I cannot understand your attitiude toward HF’s. You’re almost like some branch of the U.N. trying to protect the rights of the nation of HF’s and all its inhabitants against the evil and dictatorial forces of the V.

Weyand study confirms a longer SL for F runners that occurs in an equal air phase time. I am merely trying to say that the longer SL (which is a horizontal component) is increased because of horizontal propulsion forces that are generated by those muscles responsible for that increased SL (ie., hip flexors and extensors)

Longer SL has both V and H components. If there is no vertical element then stride length would be limited to the length of the legs. The range of SL in Weyand’s study were 2.9 to 4.9 m. If you know anyone who can stretch out to almost 10 m without leaving the ground, sign them up as a client and get them a monster contract with the NBA. If you add vertical, you add gravity. If you add gravity you add V F requirements that dwarf the HF.

Barry Ross

366

Barry, regarding you’re last point: I think that Alex is suggesting the difference between stride length in the subjects was a result of differences in horizontal forces as opposed to the difference being in vertical force due to the equal air phase time (he points out earlier the relationship between time spent in the air and vertical forces). I don’t think he was suggesting that vertical force is unneccessary - he suggests on several occasions that it is important.

But how does all of this effect training?

Even if vertical gound forces are greater during top speed, does this necessarily mean that they need to be trained substantially more than the horizontal?

367

A lot, and yes. But I will give a more complete answer in responce to CFs earlier question tomorrow

368

I’ve already explained my point before that the experimental conditions were different to those encountered in competition or at training. Laboratory, training and competitions are 3 different things. Some researches make their laboratory during training conditions (Rega/Natta), some others make their laboratory during competitions (Bruggemann). This is more interesting for me because it’s closer to the reality of my job than Weyand’s study which is a pure laboratory thing and, once again, running on flats in a downhill treadmill with a harness has little to do with sprinting with spikes on the track.
To be more precise, Rega/Natta study didn’t involved my sprinters but if it had been the case it may have help. One of my guy will appear in the next Bruggemann study, so i will use of course these new data. On the other hand, i will not waste my guys’ time in letting them to run on a downhill treadmill because the informations are useless. I’m also 99% sure they won’t agree because they would fear an injury (athletes are so “voodoo” persons…) and maybe show a speed of 8m/s, not more!

369

Ok, first off lets get the whole horizontal forces thing straightened out. It is not possible to contract any muscle fast enough voluntarily during sprinting to produce the entire horizontal component, even at the start. I believe this is what Wannagetfast was trying to illustrate in the ice expriment (correct me if Im wrong WGF).

The only time maximum voluntary contraction (MVC) is useful is imediately prior to foot contact, and this contraction is a fraction of true MVC. This potentiates the use of the series elastic component which is utilized directly after ground contact. Therefore, MVC precedes the reflex component. This method used by the body has also been shown in various movements (not just the sprinting action) to prime faster, more explosive movements.

The angle of the MVC prior to foot contact is directly into the ground (the most efficient angle to load the series elastic components). It is not at an angle backwards, because which muscle components would it be loading eccentrically if it were?

Gravity is used as a partner to facilitate the eccentric loading, and we know gravity is perpendicular to the surface. If MVC were at any other angle other than that equal to gravity, the effectivness of the reflex would be reduced. Therefore in order for the net positive acceleration to occur, there must be an increase in vertical GRF.

You may be asking, where then does the net horizontal positive force come from that causes us to accelerate? It comes from the net summation of all other body parts in the fraction of time the foot is in contact with the ground. In this manner the support leg acts as the lever through which all other forces are translated. A leg by itself cannot sprint.

Whether the ratio is 3:1 or 10:1 in regards seems to be questionable based on our data. I do not see how the ratio could decrease at higher speeds. There is less time to apply voluntary force needed to prime the elastic components at higher speeds. Therefore, increases in horizontal velocity must come from the series elastic reflex only, and in higher ratios as COG horizontal velocity increases. The reflex can only be utilized through higher vertical GRF’s. It would therefore stand to reason that higher horizontal forces are only capable through higher vertical forces.

{To whomever posted “Just Don’t think under my rep”
I am once again baffled at the amount of deconstructive criticism existing on this thread. At least be open that your intuition may be wrong based on your current level of knowledge. I would like to post that I never would think my recommendations or opinions are set in stone, but I would never post something I do not believe to be true. I always make an honest attempt to promote the correct understanding and teaching of the sprint model. I really don’t care if my opinions get bashed. They did there honest due in making you waste your time to post such an insidious flabbergasted
response. While you are reading this, I am working my 30’s, see you at the next meet.}

370

Based on this summary - and to take the science down to the track - would you think that an element of vertical take-off training should be incorporated into a sprint training program?

Too late if you disagree: since the late 70s I’ve had sprinters doing some sessions throughout the year involving high skips over 100m.

We would typically do 2x100m high skips on a safe grass surface as part of warmup before all but the most arduous sessions on the track.

At various times of the year I tried to integrate development of vertical power by rotating sets of 2x100m high skipping on a grass surface with 2x100m sprint buildup and 2x80m tyre/sled tow.

The “high skip” is a vertical action like a high jump takeoff, every third stride or occasionally on alternate legs/strides.

I used it to encourage the feel for triple extension at the top of a stride, also specific strength for that movement. But also in the (obviously) longheld belief that the vertical element of the sprinting process - particularly after acceleration tails off - is critical to the maintainance of velocity, especially in the latter stages of any sprint.

I know the contact time in sprinting is insufficient to exert maximum force as it may be applied during the impulse of a high jump/skip takeoff, but concluded that the vertical element needed attention and this type of training was part of my attempt to address it (along with power-cleans in the weightsroom etc).

Anyway, I’d welcome thoughts on the application of the science to the track (at least as pertains to developing vertical thrust into sprinting) from Bear or any of the guys who have engaged in such a “lively” and educational discussion of Weyand study and “spring theory” etc.

371

I suppose you, as a proponent of Bruggemann, also adhere to the spring-mass model as does he. However, I haven’t read anything about that in your posts. Any reason why?

372

Spring mass model is not included in the Bruggemann studies i was refering too (competition analysis), and i don’t think my contribution on this topic would be worth reading, there’s a lot of topics where i don’t give my opinion.

373

There is less time to apply voluntary force needed to prime the elastic components at higher speeds. Therefore, increases in horizontal velocity must come from the series elastic reflex only, and in higher ratios as COG horizontal velocity increases.

Why must it? I don’t think the latter statement can be deduced from the former at all. Logically and actually it doesn’t scan.

374

What follows is what I believe to be a training protocol as dictated by the spring-mass model. I believe this is what CF asked for. It is obvious to posters that not everyone accepts that model, so what I’m presenting is neither a justification of that model nor a repudiation of any other model, but instead the rational for strength training based on the model.

If the spring-mass model is correct, then there is a greater distinction between the early portion of the sprint and the later portions in regard to muscle mechanical vs. elastic energy requirements. Adding to the mix is some confusion over terms used by locomotion experts, biomechanists, and the general sprinting community (both athletes and coaches). Ground reaction force (GRF) and ground support force (GSF) are 2 examples of this since they are often misapplied. GSF is the force applied against the ground to support the bodyweight against gravity. This does not represent muscle mechanical work against the ground. GSF must increase with increases in running velocity, to the point where force could exceed 3x bodyweight. The body, through the limbs, must be able to withstand this force without collapsing. Stiffer muscles, tendons, and ligaments are necessary to increase GSF. This becomes a necessary part of the strength training protocol. Training with heavy weights increases bone density (another major component of GSF) as well as increasing muscle, tendon and ligament stiffness.

At maximal speeds, the foot makes contact with the ground and the COM passes over it causing a rapid and forced eccentric stretch of muscles, tendons and ligaments of the leg. The resulting elastic recoil plus GRF becomes a powerful force in driving the athlete at maximal speeds. This is impulse force and is not mechanically driven. The elastic recoil is part of the rapid eccentric-to-concentric contraction and is not volitional. The amount of force greater than the bodyweight is effective force; force which elevates the body against gravity. The definition of plyometric exercise (at least the standard definition) is a rapid change from eccentric-concentric contraction. Increasing the eccentric contraction and training for more rapid change to concentric contraction can increase the amount of elastic energy as well as increase the rate of release of that energy. Elastic energy is not dependent upon muscle mechanical work and therefore has a greater rate of release and is generally more powerful. So plyos are added in the weight room as part of supercompensation (a la Chu).

So weight training can be used to increase stiffness and plyos will increase rapid delivery of elastic energy. Neither one of these is volitional nor are they directional of their own accord during high speed sprinting, therefore the type of strength training necessary does not need to be specific other than increasing stiffness, and the closest match to the plyo requirements is depth jumps. This means the elimination of a lot of needless exercise routines. In addition, because effective impulses are those that exceed bodyweight, mass should be minimized.

What remains is the early portion of the race, especially the start. At submaximal speeds, there is a definite need to create force through muscle mechanical means. The same strength training routine necessary for increasing muscle stiffness, by its nature, will show increased muscle mechanical power output. Keeping excessive mass off will allow greater mass-specific force at all phases of the race, but is highly important at the start where inertia must also be included in the battle.

I believe by its nature, the spring-mass model provides for a much simpler strength training routine that can accomplish all that is necessary for an athlete to reach their maximum potential.

375

Kitkat, I do believe that teaching the vertical force variations has a good benefit to sprint performance. Many studies suggest that the three best measurements for predicting top 100-200m performers is vertical jump (vertical force production), 30m time (acceleration, and 60m time (acceleration/transition).

For starters I would like to say that I agree with the spring-mass model and the form of training Bear proposes. However, I like anyone, always have my own variations to some things. I like the simplicity that this method entails. Like I said in an earlier thread, I had always followed this same exact methodology with slightly different specs.

I think we have come a good way with our discussions! I would like to bring one extra variable into the mix that can be related to our topic. The variable is that of direct nervous system carryover from training methods that compress the spine (vertical forces). I will attempt to make this comparison, but I hope I chose a good example.

One measure which I believe to be efficient (for measuring the value of a certain exercise), is that of prescribing a specific movement directly before sprint work in low volumes and high intensities. To illustrate two exercises which work similar movements/muscles, the Romanian Deadlift and the Reverse Back Extension.

Done with similar intensities and low volumes, which would we expect to facilitate sprint performance more? I would say the Romanian Deadlift for many reasons, all having to do with the proprioceptive mechanisms. Put simply, vertical compression of the spinal chord (and the surrounding muscles) will exhibit more facilitation of neuromuscular efforts in comparison to any exercises which do not have this variable. I believe this demonstrates the value of the vertical forces in the sprint action.

I believe compression of the tissues upon contact not only primes the immediate stretch reflex, but has a lagging “window of opportunity” that makes successive contractions more explosive. My last paragraph is speculative because I have yet to read that such a fast contraction can facilitate the movements thereafter. Most of the studies I have read utilize contractions of at least 5 seconds.

376

Thanks for sharing, Bear!
Could you elaborate on the highlighted point above? Is this the only plyometric exercise you would use? For athletes of what level and how would you reach this point of preperedness in the first place? Or perhaps you are just referring to the need of vertical-nature training…
Thanks!

377

Bear: I’ve got a few problems with the bulk of your last post. But putting them aside for the time being and assuming that they are correct, why, in training, does this need significantly more emphasis than developing horizontal force?

Overcoming gravity is an issue at all stages of sprinting however at top speed, due to shorter foot contacts, the force required to overcome gravity is greater.

Thats fine. But gravity itself remains constant through out. Drag, which is the primary horizontal braking force during a race, actually increases with the square of the velocity. Therefore in order to maintain horizontal speed, in an atmosphere (fluid medium) the power requirement increases with the cube of the velocity.
Human locomotion complicates things even further since force is not always being applied (like a car would) so a majority of the time is spent in unpowered flight time with air resistance acting against.
So basically the moment you toe off you are horizontally decellerating and the faster the horizontal velocity the greater the rate of decelleration will be.
And like vertical force nearer top speed the horizontal forces must also increase due to shorter top speeds …

This is why the Weyland study is applicable to nothing but treadmill running (or perhaps in a vacuum, it’s basically as erroneous as conducting a study on gate forces and removing gravity from the method - we could always take out both and maintain velocity indefinitely :smiley: ), and why the production of horizontal force is not as trivial as suggested.

In addition if vertical forces increase beyond what is required to maintain vertical displacement as foot contact decreases, flight time will increase due to greater vertical displacement, and greater negative accelleration will occur horizontally and stride frequency will decrease.

378

Moving on to Spring-theory.

I’ve put this in a separate post because I want to address both the bulk of Bears post and Velocegatto’s invention of the perpetual motion machine.

The problem with the spring mass model as it is being portrayed here is energy loss. In all probability there is no substance in the universe that is truely elastic, there is always some degree of dampening. There are varying degrees, but all will undergo some degree of mechanical hyseresis.
If you drop a rubber ball it will lose height with each successive bonce.
By comparison the human body is quite inelastic (visoelastic), storing and returning far less energy due to greater dampening properties (The fact that the human body is largely made up of water doesn’t help the fact, neither does the fact that the mechanisms responsible for elasticity have some sponge-like properties). Because of this the there is a significant deficit between the energy returned by the elastic mechanisms of the body and the forces required for maintaining vertical displacement. So what makes up the deficit? The force has to come from somewhere.

The elastic component of sprinting is very important at some quite energy demanding phases of ground contact but they don’t provide enough force to take care of everything.

379

Sorry for my interest in semantic details, but for clarification did you mean “hysteresis” instead of “hyseresis” and “viscoelastic” instead of “visoelastic”? Thank you!

380

Dazed, I agree with what you say, elastic components cannot be the sole reason for any performance. However, even reflex arcs have there play in the sprint action. If sprinting were solely based on a reflex arc, it would not be possible to learn better sprint technique or to train for better performances. On the other hand, if it were solely a stretch reflex (not a true reflex arc) responsible for the sprint action, thinking about technique would not hinder the performance.

I believe this demonstration shows that sprint technique has both elements present, with the better performances slipping into the autonomic realm. This is not to say that there may be a magic spot within the nervous system that is both voluntary and unvoluntary to some degree. Breathing fits this category of having both attributes, it wouldn’t surprise me if it were so with other movements within the body, seperate from the diaphram.

Dazed, in regards to higher vertical forces causing the COG to rise unfavorably, the purpose to withstand the horizontal forces was to stiffen the leg, not to get more vertical displacement from the COG. Technically, the higher force toleration from the support leg, the harder the voluntary contraction preceeding the myotatic reflex could be “thrown” into the ground.

If this higher voluntary contraction could be tolerated by the stiffened support leg, it stands to reason that a higher reflexive reaction would be given in return. Therefore, more vertical and horizontal force would be generated, thus increasing horizontal velocity without increasing vertical displacement. Let me know what you think of this…