Choosing the right plyometrics box for your training is easy and quite intuitive once you understand the basic principle of plyometric training.
When your body absorbs force, for instance when your foot strikes the ground, the tendons and muscles store energy like a compressed spring. This energy can then be released in a quick, explosive movement. So when you are running, your foot strikes the ground, the leg muscles and tendons, especially the Achilles tendon absorb force, and this force is then released to propel you forward on the next step. The purpose of plyometrics is to train this ability.
So the box you jump from should be high enough to load some compressive force into your legs, but not so high that the amount of force is greater than you can effectively absorb.
Unfortunately, you never understand something just by reading about it, so do an experiment for me. Starting from a standing position with your knees bent, jump up into the air as high as you can. Good. That was part one. Now for part two, hop a few inches in the air and as soon as you land, rebound back up as high as you can.
You should’ve noticed that you were able to jump higher the second time. This is because of the energy stored by the compression of your leg muscles and tendons. You are able to use this energy to literally put a spring in your step.
Hopefully, you are familiar with this ‘springy’ feeling. It is the reason why boxers hop and skip around; doing this keeps their legs loaded with compressive energy. May people who have never heard of plyometrics know intuitively that a taking a slight hop first will help them make a big jump.
But let me ask you a question: if you jumped off a one-storey building, would you get that ‘springy’ feeling when you landed? No. You’d feel a large force being absorbed in your feet, and you’d have to pause for a second before moving on. Whereas landing from a low height makes you faster, landing from too great a height slows you down. When we do plyometrics training, we want to avoid this heavy feeling, and always get the springy feeling.
So that is the secret to picking the right box for your plyometrics workout. You need to pick a box that is just under the threshold where you lose springiness and start to get that ‘heavy’ feeling. Said differently, the box should be the highest it can be where you will still get the ‘springy’ feeling. There is only one way you can determine this height for yourself: after reading this article, go out and jump off a bunch of stuff! Familiarize yourself with these two feelings and find what height the transition from springy to heavy happens at. As you progress in plyometrics training, you will be able to absorb greater forces, and you will need higher boxes.
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