The Magic of Depth Jumps
Depth jumps almost have a mythical status in vertical jump training. On one hand they can be extremely effective at generating quick and impressive results in your jumping ability, and on the other hand, their incorrect application can very quickly lead to injury. So what do you do? For a start, you can read this article and find out what the is the best and most appropriate way to incorporate this great exercise into your training program.
WHAT IS A DEPTH JUMP
Depth jumps are an excellent exercise to help improve reactive/eccentric strength. One of the great things about them is that often they provide immediate and noticeable gains in jump height. The down side is that these short term results often lead to them being abused as a training tool (see below).
Depth jumps are simply a jump that is performed after the athlete has dropped to the ground off a platform or box. The jump should be both immediate and rapid. As the goal of depth jumps is to improve an athlete’s reactive strength, the less bending of the knees and the less time the feet are in contact with the ground, the more effective it is.
One of the more commonly heard myths about this exercise is that you should land on your toes and that your heels should not touch the ground. The rationale for this is that your heels touching the ground increases contact time.
This myth is half true. Yes your heels touching the ground may increase contact time, but the landing and jumping can still be performed sufficiently fast so that they provide plenty of reactive stimulation. The other upside to a bit of heel contact is that it helps reduce the pressure on your joints by increasing the surface area over which forces can be dissipated.
Another quick point about performing depth jumps is that they are very hard on your CNS. In order to get the most out f them you should make sure you have plenty of rest between sets (2-3 minutes at least. The more reps you perform per set, the more rest you need between sets). You should also get plenty of rest between training sessions. Even with advanced athletes I would still only recommend their use up to twice per week.
SAFETY CONCERNS
Before I continue I wanted to address one of the biggest issues that coaches have with depth jumps – safety. Over the years the abuse of them in an athletes training program has lead to many reporting injuries from their use. Due to this there are a lot of coaches who feel that only advanced athletes should use them (often quoted is the need for a minimum of a 1.5x BW squat).
This however is something that to I do not entirely agree with. Why? I believe it has more to do with the volume and the drop height causing the injuries, not the exercise itself. After all you only have to look around the various athletic chat rooms to see that there are plenty of athletes will lots of strength and training experience who have still had problems from depth jumps.
Another way to look at it is that no one argues that squats are a great way to build strength in the legs. If you have never squatted before the chances are that you would be pretty bad at it. The squat is also a reasonably advanced exercise. It requires balance, core strength, decent range of motion etc as well as strength.
Does this mean that you wouldn’t have a beginner squat? No of course not. What it does mean however is that instead of loading up the bar with 2x your bodyweight you would pick a very light weight to start with and work up from there.
The same approach should be applied to depth jumps. They are a great way to develop reactive strength. Just because you are not great at them to begin with doesn’t mean you cannot do them, it just means you have to start nice and easy. In this case nice and easy means starting with a low box and with low number of jumps until you have found a height and volume that allows you to perform the movement quickly, correctly, and most important of all, safely.
One final comment about depth jumps and training experience that I would like to make is that it is my experience that stronger, more experience athletes definitely get more out of this exercise. However it is also the case the stronger athletes generally get more out of all jumping exercises. Why? Stronger athletes have the potential to generate more force and performing plyometrics such as depth jumps and other jumping drills helps reduce the explosive strength deficit (ESD).
Less experienced and weaker athletes do not have the ability to generate much force to begin with so there ESD is generally going to be much smaller meaning they have less to gain from plyometric activities.
What is the ESD you ask? The ESD is the difference between how much force you can develop if you have an unlimited amount of time against how much force you can develop when our time is limited. A powerlifter might be able to squat 4 times his bodyweight but if he can’t jump high it just means he cannot access his strength quick enough and he has a high ESD.
A sprinter might squat only 2.5 times his bodyweight but he can access that strength much more rapidly which allows him to run so fast and often jump quite high. What does this mean to you? It basically means that if you are inexperienced and not very strong and you are going to use this exercise in your program, you would be well advised to also be doing plenty of strength work as well.
DETERMINING DROP HEIGHT
The intensity of the exercise is largely determined by the height from which you drop, and as such the box height (in conjunction with training volume) must be carefully monitored to ensure both safety and effectiveness.
If you use a box height that is too high the obvious problem is as already covered, the increased chance of injury.
The other issue related to excessive drop height is that it can create an eccentric (downward) force that is too great for the athlete’s reactive strength to handle. So even though the athlete might not injure themselves on that jump, the downward force might still be too great for them to rebound straight back up off the ground quick enough for there to be a decent training effect.
So what is an appropriate height? The most commonly prescribed method is to identify the drop height that allows you to jump the highest when performing a depth jump. The process of determining what this height is might take a bit of trial and error.
A number of authors (Chu, Baggett) suggest the following method.
Step 1. Perform a standing vertical jump (SVJ) and mark the height you touched.
Step 2. Stand on an 18 inch box and perform a depth jump trying to beat your SVJ.
Step 3. If you did not reach the same height as your SVJ, keep lowering the box in 6 inch intervals until you can reach the same or a higher point.
Step 4. If you did reach a same or higher point than your standing vertical you keep raising the height of the box in 6 inch intervals until your performance declines.
An example might be:
Standing Vertical Jump Height Touched: 290cm
Test 1 – Height Touched Off 18 inch box: 292cm
Test 2 – Height Touched Off 24 inch box: 295cm
Test 3 – Height Touched Off 30 inch box: 289cm
Optimal drop height therefore would be a 24 inch box.
The alternatively the situation might look like this:
Standing Vertical Jump Height Touched: 290cm
Test 1 – Height Touched Off 18 inch box: 287cm
Test 2 – Height Touched Off 12 inch box: 288cm
Recommendation – Insufficient strength, do not do this exercise.
This is generally accepted as very a good way to determine your optimal drop height but I don’t believe it is the best way. Comparing depth jump height to standing vertical jump height really only indicates how reactively strong you are. If you can’t match your standing vertical jump from a 12 inch box this doesn’t mean you should not do depth jumps (as suggested by Chu), it just means you are low in reactive strength
The better way for determining the optimal depth jump height is to start on a 6 inch box and work your way up in 6 inch increments until you find the drop height that results in the highest touch.
For example:
Test 1 – Height Touched Off 6 inch box: 290cm
Test 2 – Height Touched Off 12 inch box: 296cm
Test 3 – Height Touched Off 18 inch box: 293cm
Test 4 – Height Touched Off 18 inch box: 292cm
Optimal drop height in this case is 12 inches.
What about drop height for single leg depth jumps? The answer that comes to mind is to use a box half the height of your regular two foot variety. However, it isn’t quite so simple. Landing and jumping with two feet is much easier as you have two legs pretty evenly spaced apart to do not only balance you, but to generate the force required for the jump.
When you land on a single leg it is much harder for your joints and muscles to absorb the eccentric forces. For single leg depth jumps I would use exactly the same method I just outlined but I would start with a 6 inch box and move up from there in 3 inch instead. You will be surprised how dramatically your performance drops off when using the single leg version.
Speaking of drop height the next question is when should you start to increase it? Whilst progression is the key to achieving your vertical jump goals, you don’t want to do it too quickly, particularly with high impact plyometrics. You should start increasing the box height only after you have made noticeable improvements in your jump height without sacrificing the speed of the jump.
SHOULD DEPTH JUMPS BE USED ALL THE TIME
The short answer to this is no. One of the great things about this exercise is that often they provide very good gains in a short space of time. However the rate of these gains also tapers off quite quickly. What this leads to is athletes thinking that more is better so they end up doing way too much volume for too long a period of time.
It is this overuse of depth jumps that I believe has contributed to so many injuries in the past. The length of time you should use them for will once again depend on the height of the box, the volume of jumps performed, and the training experience of the athlete. Once your gains taper off take a break from them for a few months and when you come back you will be ready once again to take advantage of this exercise.
CONCLUSION
Depth jumps can be a very beneficial exercise for improving your vertical jump. They frequently rate in many coaches top 10 jumping exercises lists. However abuse of them has often resulted in injuries leaving them with a bad reputation with many coaches.
Hopefully in this article I have given you some good ideas about how to safely incorporate this interesting exercise into your vertical jump training. The key points are to start conservatively, and to use low boxes and low volume until you start to get a feel for what you can handle.
One final thing, depth jumps are just one exercise out of many you can perform to help you jump higher. If you are worried about getting injured, or that you are not sufficiently prepared to use them – then don’t. There are plenty of vertical jump exercises you can do besides this one.
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