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Thread: Plyos... all 2 legged?

  1. #11
    Quote Originally Posted by llenny
    What are your reasons for wanting to do single leg plyo's?

    llenny
    I don't have any reasons, I just thought that some one-legged plyos would be used.

  2. #12
    tc0710
    Guest
    Duxx, you are obvously well read but you may find it useful in developing your understanding to consider this quote by Lawrence J. Peter:
    "Some problems are so complex that you have to be highly intelligent and well informed just to be undecided about them."
    When it comes to science one thing to keep in mind is that in a lab the variables are fixed. So, in the real world where this is not the case can you expect the same results when the other variables are changing and competing with each other? Under what circumstances will this or that training method help you to improve?
    Quote Originally Posted by duxx
    like Mel Siff said: dangerous exercises may actualy protect you
    I have always found this idea unsettling. When thinking in these terms you must understand that the idea of "danger" is a relative term. What is dangerous for one person is not dangerous for another.

    How dangerous an exercise is is related to how large the stress is in relation to what your body can absorb at it's current funcitonal level (what you are prepared for/"level of prepardness").

    A professional boxer steps into the ring with a pregnant woman......

    If you really are ready to absorb the shock of 1 legged jumps then fine. If you are not expect bad things to happen. The trick is to challenge the system without destroying it.

    The problem with more "dangerous" exercises is that they may be excellent ways to challenge the system but the level of stress that they apply can vary greatly between any two attempts. This may be because of the high level of skill involved (and hence the problems associated with perfectly replicating this motor pattern again and again) as in the Olympic lifts or because they provide inadequate feedback as to how much stress is being applied (plyometrics). There problems are compounded by the fact that you often don't know what your body is ready to deal with at any moment in time. Some days you might be in fit shape to survive and grow other days you may be inviting injury.

    Hence, if you can solve these problems either through practice or good observation (electronic feedback mechanisms or a good coach) then the more dangerous activities may yeild benefit. If not then you are playing with fire and you have to take the risk of getting burned.

    I hope this helps you to gain a different perspective on your oppinions.

  3. #13
    Quote Originally Posted by tc0710
    I have always found this idea unsettling. When thinking in these terms you must understand that the idea of "danger" is a relative term. What is dangerous for one person is not dangerous for another.
    Tnx, TC for your relpy... I understand what you mean....
    So I should expand Siffs thought....
    No exercise is dangerous by itself, only for a particular individual at particular time
    Every exercise can cause injury, I understand that the situation is complex (I am a member of complexity theory).... but our goal is to induce adaptation not injury.... so intensity should be the highest possible but in the same time safe enough (existance of eustress and distress). This is like pushing a rock uphill, if you push it too much over the top it will fall down (catastrophe theory)...
    In the beggining, normal depth jumps are very great stressors for athlete but we lower the heights etc to lower the stress, and after some time an athlete adopt so we must increase load (until the contact time is not too much, or the technique is norma - no heal contact etc...)
    and again after some time it is not-advised to increase height any-more so then we can use one-leg depth-jump (at lower height)...
    To conclude... normal depth-jumps are also dangerous as one-leg depth jumps if you are not prepared... so again there is time and place for everything....
    Tnx TC again for your suggestions and info

  4. #14
    I agree with CF and anyone else who says that you should not use single legged hops. I do believe that most people should not use single legged hops without a qualified S & C or T & F coach bc;

    1. Most young athletes do not have the strength to do single leg hops and even though some tolerate it well in the short run they don't tolerate it at all in the long run (injury).

    2. You don't need to do single leg hops immediately, you should work up to them starting out with double leg jumps. That being said, single leg hops do increase ground contact time so doing them at the wrong time can lead to negative results or not as postive as an athlete could get if had not done those single hops in the first place!

    3. The slower the eccentric contraction the greater the loss of elastic energy. Also the longer the pause at the bottom of the SSC or (isometric contraction) the greater is the loss of the elastic energy. The faster the concentric contraction the greater the vertical displacement; therefore, the faster the concentric the greater the contribution of the SSC to the power output!

    4. Single leg hops are lower on the SSC bc the ground contact time is higher!

    You have slower movement when you have a greater external load; therefore, over time as a percentage of the Range Of the Movement you lose elastic energy at an earlier joint angle. So for example, the SSC occurs in a bench press; however, the contribution of the SSC to power output is severly reduced but it is still present.
    Double leg jumps exploit the SSC moreso than the single leg hops.


    The SSC Continuum

    slow.............................................. .....fast


    Contribution of the SSC to power output

    Low......................................High
    _______________________________________
    Maximal strength.....................Speed Strength

    ..*..................................*..........*
    [B Press]...................[S Leg Hop].[D leg Jump]

    Strength Qualities

    Fig. 5 [with adaptations] The relationship between the strength qualites and the contribution of the SSC to power output! [stars indicate where on the continuum the bench press, single leg hop, and double leg jump lie on the the continuum]


    Coupling time

    0.10s............................................. .....4.0s
    ________________________________________

    1.......2.......3.......4.......5.......6.......7. ......8

    Movement Type

    Fig. 7 The stretch-shortening continuum for hip and knee extension movements (King 1992)

    1. Ground contact time in high speed sprinting
    2. Ground contact time in power bounding
    3. Ground contact time for in-depth jumps
    [3a. Ground contact time in Double leg Jumps]
    [3b. Ground contact time in Single leg Hops]
    4. Ground contact time for depth jumps
    5. Jump squats with weight
    6. Squats with no pause in the bottom position
    7. Squats with a short pause (1-2 sec) in the
    bottom position.
    8. Squats with a long pause (2-4 sec) in the bottom position.

    Most of the above information was material out of Ian King's Plyometric Training Series except for point number 1. Below is my take on the matter.

    I do disagree with CF and others that you should avoid using Single Leg Hops bc if you have the strength in place and all the other factors in place then you can use Single Leg Hops; however, you should know why you are using sing leg hops and when. The graphs above should tell you that doing single hops will help you but not as much as Double Leg Jumps when it comes to the contribution of the SSC to power output and also the ground contact time.


    Reasons for doing Single Hops,

    1. One may use single leg hops to increase the Motor Unit Involvement in the single leg. You use more Motor Units in a Single Leg Hop then you do in a Double Leg Jump if you take into account the volume of only one leg (i.e. just the right leg or just the left leg) or combine the volume of left and right single leg hops.

    2. If you have an injury on one leg like a hamstring pull then you can do single leg hops on the good leg till you heal. Once you have healed you can do single hops on the healed leg (assuming you already have the requirements for being able to do single leg hops, such as strength and etc.) to equate the volume and then later on both legs for motor coordination and integration back into sprinting with both legs being equally powerful (I'm not suggesting you do sprinting when focusing on the good leg or the healed leg in single leg hops bc this will lead to muscle imbalance issues and will cause injury).

    3. Sprinting after the blocks is done with only 1 leg on the ground at any time. For this reason single leg hops maybe more beneficial then double leg hops.

    4. The coordination of an individual in terms of his lower extremities is enhanced moreso with single leg hops over double leg jumps.

    5. Sport Specificity - So for an athlete like a high jumper, triple jumper, or a long jumper single leg hops are more beneficial. In other words, they should be done at a higher volume then sprinters would!

  5. #15
    Administrator Charlie Francis's Avatar
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    Single leg hops: Re Your Points:
    1: MU involvement is only increased when you consider the support muscles- which can be trained safely at a lower intensity seperately. Intensity can be higher with one leg if done in exactly the same way a double leg. Intensity with double legs can be increaed safely by altering the starting height etc.
    2: A reasonable point though one leg power speed exercises, which are described in rehab discussions in the Forum Review and elsewhere, are used for the likely short period it takes for recovery.
    3: This is the same specificity arguement which is used against every general strength training element. Again, see the General vs Specific weight training arguements in the Forum Review.
    4: This can be done with bounding drills, which I consider separately as part of the Power Speed componant (based on CNS intensity). Perhaps I haven't been very clear about this.
    5: True for jumpers.

  6. #16
    Administrator Charlie Francis's Avatar
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    Quote Originally Posted by tc0710
    Duxx, you are obvously well read but you may find it useful in developing your understanding to consider this quote by Lawrence J. Peter:

    When it comes to science one thing to keep in mind is that in a lab the variables are fixed. So, in the real world where this is not the case can you expect the same results when the other variables are changing and competing with each other? Under what circumstances will this or that training method help you to improve?

    I have always found this idea unsettling. When thinking in these terms you must understand that the idea of "danger" is a relative term. What is dangerous for one person is not dangerous for another.

    How dangerous an exercise is is related to how large the stress is in relation to what your body can absorb at it's current funcitonal level (what you are prepared for/"level of prepardness").

    A professional boxer steps into the ring with a pregnant woman......

    If you really are ready to absorb the shock of 1 legged jumps then fine. If you are not expect bad things to happen. The trick is to challenge the system without destroying it.

    The problem with more "dangerous" exercises is that they may be excellent ways to challenge the system but the level of stress that they apply can vary greatly between any two attempts. This may be because of the high level of skill involved (and hence the problems associated with perfectly replicating this motor pattern again and again) as in the Olympic lifts or because they provide inadequate feedback as to how much stress is being applied (plyometrics). There problems are compounded by the fact that you often don't know what your body is ready to deal with at any moment in time. Some days you might be in fit shape to survive and grow other days you may be inviting injury.

    Hence, if you can solve these problems either through practice or good observation (electronic feedback mechanisms or a good coach) then the more dangerous activities may yeild benefit. If not then you are playing with fire and you have to take the risk of getting burned.

    I hope this helps you to gain a different perspective on your oppinions.
    Some very good points, though I'd modify the one danger element to: A professional boxer stepping into a hotel room with a woman at 4AM!

  7. #17
    Administrator Charlie Francis's Avatar
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    Herb: Don't do stuff just cause I say so! (I know you don't, cause if you did, you wouldn't do Ultimate Fighting!)

  8. #18
    Quote Originally Posted by Charlie Francis
    Herb: Don't do stuff just cause I say so! (I know you don't, cause if you did, you wouldn't do Ultimate Fighting!)
    Maybe he should switch over to the career of a Cheeleader!

    LOL, LMFAO, ROFL, ROFLMFAO!

    Don't kill me just yet Herb, I still need at least 1 good pom pom for CF myself!

  9. #19
    Quote Originally Posted by Charlie Francis
    Some very good points, though I'd modify the one danger element to: A professional boxer stepping into a hotel room with a woman at 4AM!
    CF=PHD ( professional humorist )

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