jumping activity in badminton players is important. i working on my research to see about optimal knee angles when doing a countermovement jump in plyometrics. does anyone have a paper to explain about a knee angles and a optimum height and power while doing a vertical jump. and EMG muscle activity in lower extrimity.
Would be difficult to have a protocol for an exact angle for all athletes. What would contribute best to making sure all are performing the jump appropriately is to make sure that all participants have good ankle dorsiflexion. From there the rest is likely intrinsic. Hope this helps.
Dear Donny,
There is no one optimal angle for everybody. Everyone has it own optimal knee angle. If you measure the size of lower “extremities parts” (lower leg, femur) you will notice the extreme differences from person to person. Some has longer lower leg, some has longer upper leg in proportion. Therefore there are big differences between force arms. But you can find the asked by measuring the knee force curve from person to person. I think there is a good test find the optimum knee angle - the isokinetic force measuring procedure in sitting position. You have to start the stretch from a low knee angle till you reach the straightened position. The optimum knee angle is the angle when the force curve reaches the highest point during the knee straightening. I think it will be approximately 98 to 110 degree for countermovement jumps.
Hi Donny,
I think the optimum knee angle is as small as possible because a countermovement primarily serves to take up slack in the muscle-tendon unit. Since a movement with countermovement takes more time to complete than a movement without countermovement, minimizing the amplitude of the countermovement is important for all sports situations that involve time pressure. Therefore, optimum jump height and power output may be less important than a fast rate of force development and indeed, in many situations jump height is compromised for a fast movement time.
The paper in which we expand on this discussion has yet to be published, but I expect it will be published within two months in the strength and conditioning journal.
Hope this helps!
Hi Donny,
All the answer above are good and complete about your question.
However, how in the plyometric training is necessary stretch‐shortening cycle movements that involve a high‐intensity eccentric contraction immediately after a rapid and powerful concentric contraction it is not usual to establish a specific angle in this kind of training. In my opnion the most important thing that you need to make is to control the movement during the exercise and try to protect your clients or sample. Recently, I´m using the plyometric traning in obese children and I had good results on the motor coordination and physical fitness.
Hope this helps!!
100% agreed with Marcos... it won't be useful to find the "optimal" angle for sucessive repetitions.
http://journals.lww.com/nsca-jscr/Abstract/2010/09000/Vertical_Jump_Biomechanics_after_Plyometric,.24.aspx
Best of luck!
I think the linked paper below (Jidovtseff et al., 2014) and the attached paper (Bobbert et al., 2008) may be of interest with regards to optimal depths. Although papers tend to report power, please keep in mind that this is not a good measure or predictor for jump height. See the attached papers for more on that.
Article Jumping: Power or Impulse?
Article Influence of jumping strategy on kinetic and kinematic variables
Article Jumping depends on impulse not power
Chapter Critical Appraisal of Jumping as a Measure of Human Power
Maybe this article could provide you some insight into difference between optimum and self-selected depth.
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