In the video above, the first few box jumps that are done are performed are done in a normal “jump up, step down” style. The next few are done with a rebound and are known as “bounded box jumps.” So, the logical question, especially after watching high level athletes do the latter, is – “Should I bound my box jumps?”
Well, that depends. (Of course I had to say that)
First things first, let’s clarify exactly what box jumps are a – plyometric exercise; meaning that they are movements in which muscles exert maximum force in short intervals of time, with the goal of increasing power. A reliance on the elastic properties of muscle fibers is what makes a box jump happen.
Proper execution relies in the participants ability to coordinate a stretch, or lengthening, of the muscle fiber, followed by a rapid and explosive contraction.
Now let’s get into the differences in the two styles:
In the more common step down style, each repetition is initiated with a counter-movement. The athlete starts from a full standing position, then quickly hinges the hips back and bends at the knees. This serves to stretch the muscle fibers that are responsible for propelling you upward. Not to go down the rabbit hole too far, this is known as activating the “stretch-shortening-cycle.” This stretch creates stored elastic energy, similar to how compressing a spring or stretching a rubber band works. Once the direction is reversed, that energy is released in an explosive manner, thus propelling you upwards. In order for this synchronization to really pay off, two things need to happen:
- The depth of your counter movement (bending at hips and knees) should be short
- The speed of your change of direction must be quick and deliberate. Any delay in the turnaround and you’ve lost the benefits of the SSC
In the less common bounding style, the first rep is initiated with a traditional counter movement as in the step-down style. After that, the following repetitions are still initiated with a counter movement, albeit a much more aggressive one. As the athlete hops down from the box, they will contact the ground while using their legs like shock absorbers and quickly use that stored elastic energy to jump right back up. If you could slow that video above down a bit, you’d see exactly what I’m referring too. In traditional strength and conditioning, this part of the movement (starting from a high surface, dropping to floor, and jumping right back up) is known as a depth jump. An important note: If your heels come into contact with the ground upon your descent, you have effectively cut out the benefit of the stretch shortening cycle. Instead, you are punishing your entire body as it falls to the ground like a sack of potatoes. Don’t do that. (You know who you are).
Now to answer the question at hand – should YOU bound you box jumps?
Well, the advantage to the bounded box jumps is that they are faster. You can perform more reps in a given interval of time vs the step-down style.
But there is a caveat – increased amount of reps in the same time frame means that your breathing rate will increase; for some folks, it will do so considerably. If you haven’t yet mastered how to work with a high breath rate, then you aren’t ready for bounded box jumps. Having said that (about the speed thing that is), we’ve tested the difference during the Open. Even stepping up and step down. Especially for taller athletes. A woman over 5’7″ can do 20 step ups (20″) only about 3 sec slower than 20 box jumps. And keep her HR way down.
But most importantly, the much more aggressive nature of the bounding style lends itself to injury of the achilles tendon. Just ask Julie Foucher or Alethea Boon.
No…doing them does not guarantee an injury. Hundreds of them are done day in and day out in gyms around the world. Even more so when the competition season heats up.
So the question you need to ask yourself is – does the risk of the more advanced movement outweigh the reward of its execution?
If you are currently a Regionals or Games level athlete, then I assume you know the answer – its a must at that level. Thats like asking a major league hitter if he really needs to be able to hit a 95mph fastball. Its part of the sport – the answer is a resounding yes.
If you’re a recreational level CrossFitter, or local competition person, the answer is no. Just to be clear – this covers 99.9% of ALL people who dabble in CrossFit. The time difference just doesn’t make it worth it. You remember Jay, our Games athlete? Yea…he bounds his box jumps…but only the first few because of the “free speed” your body provides early on in a workout. I won’t elaborate on the physiology aspect, but hopefully you get the point.
If the higher level of competition is something you aspire to, then its a skill that you will need at some point. But just like it takes time to develop the capacity to deadlift 405lb for reps, or snatch 300lb, or do 50 C2B pull-ups unbroken, learning to bound your box jumps and subsequently increase your capacity in that movement will take time. Don’t go from step-down style on a 24″ box straight into trying to bound on a 24″ box. Don’t even start on a 20″ box. Start on a couple of 45lb plates stacked on each other. Increase the intensity (hmm…where have you heard that before?) over a long time frame.
Not sure exactly how to do this progressively? Ask me.