A recent Twitter video brought depth drops back into the picture. The athlete in the video “drops” off a stacked pile of plyo boxes about 2 meters in height and goes into a rebound jump.
2m10???????????DJ??DJ-index?2.0???— ??? / Ryohei Hayashi, PhD (@fftft414) January 8, 2021
Some coaches marveled at the athleticism. I cringed at the stupidity and, what that stupidity might lead too.
I let my feelings be known in the responses. This of course led to a number of “why not” type responses from some coaches. (The worst part was I was written off as a social media influencer).
First off, lets attempt to define what we saw. Technically the video was a Depth Drop to a rebound. The athlete did not attempt to re-jump as much as he seemed to simply react elastically to the ground. Imagine dropping a basketball from 6 feet.
Verkhoshansky used what he called Depth Jumps and recommended a height of .75 to 1 meter. Komi and later Bosco advocated a Drop Jump from 60 cm. Although similar they had some differences. In any case, Bosco also felt that heights higher than 60 cm could be dangerous. (N Verkhoshansky CVSAP 2013)
In both cases (Verkhoshansky and Bosco) the goal was to use the force of gravity to overload the muscle-tendon unit.
The net result of these so called “shock methods” was in some cases elite performance and in other cases injury. These types of exercises were popular in the late seventies and early 80's.
“The way drop jumping has become popular is typical of how training methods evolve. It is rumored that the Russian athlete who won the 100 and 200m dash in the 1972 Olympics, Valery Borzov, utilized plyometric drills as part of his training (Wilt, 1978). Coaches of rival athletes became interested and began to search for more information. They found a description of drop jumping in a translated Russian paper by Verkhoshansky (1966), and adopted the idea and developed their own modifications. These modifications are now incorporated in widespread athletic programs” (Bobbert, 1990)
Believe it or not in the late seventies and early 80's this led some coaches to take athletes up into the bleachers and jump off the back. In our more-is-better world we tossed caution to the wind and endangered lots of athletes.
Because of the misuse and misunderstanding of this technique we have not advocated and or used Depth Drops or Depth Jumps in our training. In the last two years we have experimented with some eccentric overload drops with no rebound.
However, we limited these to 10% higher than the best vertical jump in order to create controlled overload. The athlete in the Twitter clip was dropping from 2+ meters. This could be in the neighborhood of 80-100% overload, assuming a vertical jump between 30 and 40 inches.
The Twitter rationale used to defend this was that kids routinely jump down from heights that might approach their own measured height in play situations and that as result depth jumps/ drops etc. are therefore safe.
This is a short sighted rationale on a number of fronts.
- In the simplest sense we have to look at the idea that because a kid does it, it is therefore safe for adults/ athletes? Children are probably much more elastic than adults and also have far less “mileage”. Also, kids do lots of dumb things and survive, however that doesn't place those things on the recommended list.
- Although kids may “jump down” we must really ask ourselves what is the frequency/ volume of these landings. My guess is that they are actually quite rare. In training athletes we would be doing these types of drops/ landings quite regularly I would assume.
- In addition, kids may have “ juicy tendons” but, two of the leading childhood pain syndromes are Osgoods-Schlatters Disease ( an overuse syndrome of the tibial tuberosity) and Sever's Disease ( an overuse syndrome of the achilles insertion). It should be noted that neither of these are actual diseases but rather overuse syndromes. My only point here is that kids can and do get overuse syndromes similar to adults and, that these issues may be caused by reckless play.
Another point that must be made is that in sport we never have to come down from higher than we can jump up. Production of these forces can only be obtained artificially. In the video that prompted this article, the athlete actually uses a ladder to get to the tops of the boxes.
My fear is that a video like this will fuel imitators. If experience teaches us anything it's that people love to imitate cool stuff they see on the internet. I can see a depth drop craze similar to the high box jump craze with people attempting to survive higher and higher drops. Failure will be catastrophic as we all wait for the inevitable gym fail video of a patella tendon rupture.
Watching this video brought me back to a recent Jacked Athlete Podcast where host Jake Tuura interviewed Jill Cook, one of the world's pre-eminent experts on tendonitis. Cook made a simple statement that caught my ear. She said “ I have no idea why anyone would jump down from a height higher than they could jump up too”? Yes, one of the worlds preeminent authorities on patella tendon and patella femoral issues thinks this is a really dumb idea too. As I said above, I can justify 10% higher than the best vertical jump in order to create on overload but, not nearly 100% more.
I messaged a young coach who praised the video and reminded him that if we seek to be social media influencers or content curators that this comes with a responsibility. We must exercise good judgement and caution, knowing that impressionable athletes and impressionable coaches are watching, listening and reading.
N Verkhoshansky. Depth Jump vs Drop Jump. CVASPS.com 2013 web archive
Fred Wilt. “Plyometrics – What is it and how it works”, Modern athlete and coach, 1978, n.16, pp.9-12.
F. Bobbert. Drop Jumping as a Training Method for Jumping Ability. Sports Medicine 9(1):7-22, 1990. (Page 8).