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Thread: How much knee flexion in depth jumps?

  1. #21
    Quote Originally Posted by James Smith
    considering where in the amplitude the greatest magnitude of force is produced we know that the knee position held during ground contact on depth jumps is where, plus or minus a small degree, the most significant gains will occur. As a result, the knee position must be specific, as I stated, to the reason for including the depth jumps in the program.

    Examples:
    - a ski jumper would match the knee position during take off on the ramp
    - an NFL prospect training the counter movement vertical jump for the combine would match the knee position they typically descend to during a counter movement
    - a volleyball player would match the knee position they typically descend to during sport play prior to blocking/hitting at the net, or serving
    - a T&F jumper would match the knee position they descend to prior to take off in the single leg variants
    - and so on

    Regarding coupling time, this must also be specific to the sport being trained for regarding the ground contact times associated with particular aspects of competition in which explosive jumps occur.

    If the coupling time of the depth jump in training far exceeds that which the athlete has time for during that aspect of their discipline then the reliability of the transfer becomes diminished.

    Again, we must acknowledge the reason for using the depth jump. If the reason is rooted in improving the performance of a specific aspect of sport from a kinematic and neuromuscular standpoint then a greater degree of dynamic correspondence must be satisfied in order to ensure positive transfer.

    Alternatively, if the goal is less concrete then less criteria need be satisfied in order to attain positive transfer. One such example might be the use of the depth jump as a neuromuscular primer for a subsequent tonic or speed strength activity.
    With the level of specific movement you tend gravitate towards, do you find any reason for track and field jumpers to use depth jumps to improve the jump itself?

    With the double leg movements not really being specific to their task. And single leg jumps having too high of contact times.

  2. #22
    Quote Originally Posted by popequique
    With the level of specific movement you tend gravitate towards, do you find any reason for track and field jumpers to use depth jumps to improve the jump itself?

    With the double leg movements not really being specific to their task. And single leg jumps having too high of contact times.
    Excellent point!
    Also, would a basketball player who already can jump pretty high, from a good height with a smaller knee bend and GCT, intentionally increase the GCT and knee bend just to be more specific?

  3. #23
    Quote Originally Posted by James Smith
    considering where in the amplitude the greatest magnitude of force is produced we know that the knee position held during ground contact on depth jumps is where, plus or minus a small degree, the most significant gains will occur<snip>...
    Has this been specifically documented in any study? Could you please point me to the empircal data?



    Regarding coupling time, this must also be specific to the sport being trained for regarding the ground contact times associated with particular aspects of competition in which explosive jumps occur.

    If the coupling time of the depth jump in training far exceeds that which the athlete has time for during that aspect of their discipline then the reliability of the transfer becomes diminished.
    Has this been documented in any study? Could you please point me to the empircal data?

    Again, we must acknowledge the reason for using the depth jump. If the reason is rooted in improving the performance of a specific aspect of sport from a kinematic and neuromuscular standpoint then a greater degree of dynamic correspondence must be satisfied in order to ensure positive transfer.
    I here this mantra repeated over and over, but it simply doesn't apply to all methods of training. In the most basic of exercises, the squat, one that most athletes perform to enhance speed, explosive strength etc., its simply not true. Running and jumping are extremely rapid, explosive, movements. If you squat in that manner, very light weight is required. There is no question that athletes doing dynamic squats only would not be able to realize the same benefits that athletes doing much slower, heavier, max effort squats would realize. Here the dynamic correspondence actually correlates inversely. Interestingly, knee flexion also does not correlate, as knee flexion in sprinting and even explosive jumping is minimal, while it is openly acknowledged that shallow squats offer very little benefit...in fact many on this board suggest ATG squats are the most beneficial. If squats with little dynamic correlation are actually more beneficial as a training aid for sprinting and jumping than squats performed in a more 'dynamically correlated' fashion, how do we know that depth jumps or box jumps must be dynamically correlated for best results? Again, is there a study which tests this question empirically?

  4. #24
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    Quote Originally Posted by star61
    Has this been specifically documented in any study? Could you please point me to the empircal data?



    Has this been documented in any study? Could you please point me to the empircal data?

    I here this mantra repeated over and over, but it simply doesn't apply to all methods of training. In the most basic of exercises, the squat, one that most athletes perform to enhance speed, explosive strength etc., its simply not true. Running and jumping are extremely rapid, explosive, movements. If you squat in that manner, very light weight is required. There is no question that athletes doing dynamic squats only would not be able to realize the same benefits that athletes doing much slower, heavier, max effort squats would realize. Here the dynamic correspondence actually correlates inversely. Interestingly, knee flexion also does not correlate, as knee flexion in sprinting and even explosive jumping is minimal, while it is openly acknowledged that shallow squats offer very little benefit...in fact many on this board suggest ATG squats are the most beneficial. If squats with little dynamic correlation are actually more beneficial as a training aid for sprinting and jumping than squats performed in a more 'dynamically correlated' fashion, how do we know that depth jumps or box jumps must be dynamically correlated for best results? Again, is there a study which tests this question empirically?
    You seem to be forgetting the purpose of each exercise and element. People use squats and other lifts to improve maximal strength as a general quality. Specifically, you want glute/hamstring/lower back strength and the like, but it acts as a general element in the program that has to interact with the rest of the program.

    Depth jumps and vertical plyos are teaching vertical power production, hence why you tend to use vertical plyos more in phases where you're emphasizing top speed rather than acceleration (where you would focus more on jumps with more deep knee bend). This has been discussed by many coaches, including CF.

    If you do depth jumps from too high, you lose a lot of the elastic response and you aren't really even doing a plyometric activity in some extreme cases.

    When you talk about studies, what studies are you looking for? Ones done on hung over college kids looking for a few bucks (like most studies) or ones with very specific populations or what? A number of coaches have discussed this and presented their results (good and bad), which should give us plenty of empirical evidence for those beliefs. At this point, applying many studies on sports enhancement would be applying misinformation or limited information at best.

  5. #25
    Quote Originally Posted by Davan
    When you talk about studies, what studies are you looking for? Ones done on hung over college kids looking for a few bucks (like most studies) or ones with very specific populations or what?
    That or the Verkhoshansky studies where the depth jump results graphs shoot into the stratosphere.

  6. #26
    Quote Originally Posted by popequique
    With the level of specific movement you tend gravitate towards, do you find any reason for track and field jumpers to use depth jumps to improve the jump itself?

    With the double leg movements not really being specific to their task. And single leg jumps having too high of contact times.
    Possibly they act as a sort of lightened method - i.e., the forces in the triple are far greater than those *generally* in a depth jump (both feet)?

  7. #27
    Quote Originally Posted by Stevemac24
    Possibly they act as a sort of lightened method - i.e., the forces in the triple are far greater than those *generally* in a depth jump (both feet)?
    Perhaps, but then I still do not see how double leg depth jumps would come close enough to mimicking the way force is applied to only a single leg at take off (no support from the other leg). Also that is assuming you believe that the exercise should be of such a specific nature like James, otherwise I see your point.

  8. #28
    Quote Originally Posted by mortac8
    That or the Verkhoshansky studies where the depth jump results graphs shoot into the stratosphere.
    I like how over half of Verkohoshanky's references in that piece are related to his own works. Must think highly of himself. Seriously 34 references and 22 of them are of himself.

  9. #29
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    Quote Originally Posted by star61
    I here this mantra repeated over and over, but it simply doesn't apply to all methods of training. In the most basic of exercises, the squat, one that most athletes perform to enhance speed, explosive strength etc., its simply not true. Running and jumping are extremely rapid, explosive, movements. If you squat in that manner, very light weight is required. There is no question that athletes doing dynamic squats only would not be able to realize the same benefits that athletes doing much slower, heavier, max effort squats would realize. Here the dynamic correspondence actually correlates inversely. Interestingly, knee flexion also does not correlate, as knee flexion in sprinting and even explosive jumping is minimal, while it is openly acknowledged that shallow squats offer very little benefit...in fact many on this board suggest ATG squats are the most beneficial. If squats with little dynamic correlation are actually more beneficial as a training aid for sprinting and jumping than squats performed in a more 'dynamically correlated' fashion, how do we know that depth jumps or box jumps must be dynamically correlated for best results? Again, is there a study which tests this question empirically?
    What I will state is that, regarding dynamic correspondence, it is not possible to draw an inverse correlation. what is possible and too often commonplace amongst western sports coaches is an incomplete understanding of transference.

    Those who sufficiently understand dynamic correspondence think much differently about this type of discussion and also understand the particularities of the full criteria:

    - amplitude and direction of movement
    - accentuated region of force production
    - dynamics of effort
    - rate and time of maximum force production
    - regime of muscular work

    It is erroneous to mention squats within the context of a specific speed development means because those of us who are fully informed of the biodynamic and bioenergetic foundations of sport disciplines and training means know that there is nothing more specific to sprinting then sprinting and the biodynamic characteristics of the squat lift are too distant to register high in transference at best to anything more than particular aspects of sprinting.

    The benefit of the squat towards speed development, as Davan well pointed out, is one of the improvement of general strength.

    If squats registered as high in transference as sprinting, relative to sprint development, you could rest assured that sprinters would sprint much less in favor of squatting; but don't hold your breath on that one.

    I'm not sure what you consider to be 'openly acknowledged' regarding squat depth; however, you should know that full squats are a more general strength means relative to sprinting while half and quarter squats register much higher in transference- all the while being far lower in transference then sprint variations.

    The level of context that must be applied in order to have an intelligent discussion regarding training is of the utmost importance.

    The concept of transference is only as meaningful as the identification of the level of preparation of the athlete.

    The lesser the qualification the more disjointed the state of preparation; hence, the higher the transference of a wider variety of training means and the greater the significance of higher volumes of non-specific training.

    As the athlete, in this case, the sprinter, becomes faster it becomes more challenging to yield high transference out of a wider variety of means and, as a result, the complex of means becomes reduced throughout the career of athletes who participate in the sprints and T&F disciplines in general.

    As time moves forward GPP eventually requires much shorter stages of training to maintain/re-elevate it to sufficient enough levels to support and concentrate the SPP efforts.

    As a result, it is meaningless to discuss the relationship between squat, jump, and sprint without isolating qualification level and due to the information I have just provided we know that it becomes more and more futile to debate the training of those lesser in qualification.

    Regarding high qualification in the sprints (ergo sub 10.1) we know that physical preparation must be very high simply in order to attain such results. We also know that the specific characteristics of each athletes training history, morphology, special preparation levels, and so on must be identified, again, in order to have some type of meaningful discussion.

    This is illustrated ever so clearly in Bondarchuk's Transfer of Training text (note how the data was gathered from national and world champions due to the futile nature of conducting such testing on lesser qualified athletes)

    Regarding my statements about coupling time and joint positions I encourage you to more fully examine dynamic correspondence and, more than isolated studies, I would encourage you to review as much translated literature as you can acquire.

  10. #30
    Quote Originally Posted by James Smith
    ,...,<snip>...It is erroneous to mention squats within the context of a specific speed development means because those of us who are fully informed... <snip>
    I didn't mention squats in the context of specific speed development. I compared the use of squats to the use of depth jumps, both of which are general training tools, rather than specific to sprint training development. You stated that the training form of the depth jump should match the the intended sport movement specifically, in terms of knee flexion and coupling time. Why is it necessary to duplicate, as closely as possible, knee flexion and coupling time when performing depth jumps to maximize benefits, when another general training exercise, the squat, produces greater benefits when knee flexion and coupling time do not correspond to knee flexion and coupling times measured during sprinting or jumping?

    If squats registered as high in transference as sprinting, relative to sprint development, you could rest assured that sprinters would sprint much less in favor of squatting; but don't hold your breath on that one.
    Actually, from what I've gathered on this forum, it is recommended that all sprinters, including elite sprinters, perform squats of some kind regularly, whether back squats, Olympic squats or front squats as part of a power clean. Of course squats don't have the high transference that sprinting itself does, but we we weren't comparing squatting to sprinting, we were comparing squatting to depth jumps.

    I'm not sure what you consider to be 'openly acknowledged' regarding squat depth; however, you should know that full squats are a more general strength means relative to sprinting while half and quarter squats register much higher in transference- all the while being far lower in transference then sprint variations.
    Awesome. Could you point me to an empirical study showing half squats superior to ATG squats in terms of transference...I would love to have that one in my ammo bag. And by the way, can you also show me an empirical study that suggests quarter squats produce more benefits for sprinters than either half or ATG squats? I'll be running sub 10.0 in no time.

    ...As a result, it is meaningless to discuss the relationship between squat, jump, and sprint without isolating qualification level and due to the information I have just provided we know that it becomes more and more futile to debate the training of those lesser in qualification.
    So what you're saying is that until an athete can run a 10.1 100m, it really doesn't matter how he squats or jumps.


    So...for the majority of athletes on this board who want to run faster and are thinking about including depth jumps in their general training program, how much knee flexion and what type of coupling times do you recommend?

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