Why Did My Vertical Jump Decrease? 6 Reasons

There’s nothing more deflating as an athlete than getting amped up to test your vertical but then seeing that your numbers went down…

You work so hard every day doing everything you can to jump just a tiny bit higher and then when your vert actually goes down, it’s a massive kick in the teeth.

In this article we’re going to look at the six most common causes of a vertical jump going the wrong direction and the things to be aware of to make sure you avoid these pitfalls.

Understanding Yourself As A Jumper

Before we jump into the specifics, you need to be extremely conscious of what kind of an athlete you are and how you respond to various stimuli.

Do any of these terms describe you? Tall, skinny, lanky, long-limbed, of slight build?

If this resonates, you’re probably the type of athlete who responds pretty well to plyometric training but may struggle improving size and strength in the gym.

These athletes can jump around all day and tend to recover fairly quickly from explosive movements.

Are you a big, strong guy with thick thighs, calves, and a well developed upper body?

These athletes tend to thrive in the weightroom and have a tougher time executing fast, explosive, plyometric oriented training.

These guys can lift all day no problem, but an intense plyometrics session may take them much longer to bounce back from.

Pun intended.

Most athletes make pretty big mistakes when it comes to recovery and part of that comes from not knowing what your body responds to and can recover from over what time period.

I urge you to think critically about what your strengths and weaknesses are and what you respond well and poorly to, because it should play a big role in how you configure your training routine and may explain why you’re not improving.

What’s Your Explosive Strength Deficit?

The explosive strength deficit is the difference between your overall total strength and how much of that raw strength you can actually use in a sport specific movement.

In the vertical jump, we might use a measure like the one rep max back squat to determine our overall strength and of course the vertical jump will be the test of how much of that pure strength we can actually utilize.

If you’re really strong (i.e. can squat a lot) but jump relatively low, you have a high ESD. If your jump is quite good, but you’re kind of weak, your ESD is low.

In the latter case, you’re able to leverage a higher percentage of the strength you do have.

If you’re an athlete serious about your vertical jump training, you should be regularly testing your overall strength (maybe you choose to use the back squat for that) as well as your vertical jump.

If you notice your strength increasing but jump not increasing, you are increasing your ESD (this is bad).

If your max squat is 100 lbs and your vertical is 20″, and you increase your squat to 120 lbs and your vertical increases to 25″, then you improve your squat by 20% and vertical by 25%, so you bridge that gap slightly, and your ESD comes down. This is good!

You should always be looking to get stronger and jump higher and at least maintain or improve (decrease) your ESD.

A lot of the reasons I’m about to elaborate on come about because people fail to understand themselves as an athlete and end up increasing their ESD in some way.

By listening to your body and learning as much about the science of jump training as possible, you should be able to avoid all of these!

Let’s begin!

1. You’re Temporarily Fatigued

Another way of putting this would be, ‘your vertical jump didn’t actually go down’.

There’s so many factors that can influence a temporary decrease in vertical jump.

• Did you sleep poorly the night before?
• Maybe there was a cute girl in the gym when you tested your vertical the last time (CNS stimulation).
• Maybe you did a heavy squat workout yesterday and your muscles haven’t fully recovered.
• Maybe you haven’t done a number 2 in while and you’ve just drank a gallon of water (you’re heavier than usual).

The list goes on and on.

If you’re testing your vertical every week, I wouldn’t care about week-to-week fluctuations a single bit.

There’s just too many external factors that looking at your vertical with this degree of granularity is simply counterproductive.

Maybe you’re in the middle of a strength focused training block where you’re lifting heavy and doing a lot less jumping, if this is the case, that’s a perfectly reasonable explanation for the reduced vertical.

As soon as you start focusing more on jumping again, you should see that vertical go right back up to at least where it was before.

So if you’re wondering why you could grab the rim last week but can barely touch it now, don’t be too disappointed. Your vertical will fluctuate quite a lot over the near term.

Intra-workout Vertical Jump Decline

When I was in high school, I could dunk during warmups pretty easily… but there was no chance of me throwing down at the end of a game.

The longer you work out for, the more your muscles fatigue. This should be obvious. Don’t expect to have the same bounce after a game as you would at the start.

This will affect different people different amounts and largely has to do with the composition of muscle fibers in your body.

In subjects with a high proportion of fast twitch fibres, more lactate will be formed at the same exercise intensity. This is advantageous for short intense exercise but impairs endurance performance.¹https://pubmed.ncbi.nlm.nih.gov/6913478/

Some people seem to be able to perform really well hours into a workout and others seem to exhibit quite a big drop off.

Cardiovascular fitness and endurance are required to prevent massive drop-offs in vertical jump performance throughout a session, so make sure you don’t neglect this!

2. You Are Chronically Fatigued

In my opinion this is by far the biggest mistake anyone can make in their training as an athlete and it affects a huge amount of people without them even realizing it. I was a major offender too.

When I was in high school and training full time for volleyball, my schedule looked something like this.

• 8 hour school day 5 days a week
• 4 hours courtwork after school 5 days a week (lots of jumping)
• 2 hours resistance training after courtwork 5 days a week (heavy lifts and intense plyos)
• Saturday volleyball/basketball game in AM ~1 hour
• Sunday state volleyball training in afternoon ~2 hours
• 5am wake up and squat 5×5 before school 5 days a week*

*The reason I thought it was a great idea to get up early and get some extra squats in every morning was ironically because I wasn’t making much progress…

My lifts weren’t improving much, my vertical wasn’t improving at all, I was up all night studying for exams, running on about 2-4 hours of poor quality sleep, and my diet was nowhere near on point.

And I was completely addicted to coffee at age 17!

It should be pretty obvious that I was shooting myself in the foot that whole time.

My example here is pretty extreme, but likely isn’t all that different from a lot of you. In my opinion, even half this training volume would be far too much for optimal vertical jump gains.

I ended high school with patellar tendonitis in both knees, meniscus tears in both knees, and a pretty dodgy shoulder. There wasn’t a single athlete in my ‘elite development program’ who didn’t have similar injuries.

It’s so easy to think you just need to get more reps, do more sets, lift heavier weights, and spend more hours in the gym to get to where you want to be…

The reality is this simply isn’t the case.

If you’re doing any serious amount of basketball or volleyball or other sports each week, you need to be extremely careful about adding in any additional jump training to the mix.

It is so, so easy to make the same mistake I did and you’ll get absolutely nowhere!

Focus Areas If You’re Overtrained

If any of the above resonates with you, here are the most important things to think about.

• Improve Sleep – This is by far the most underrated thing about recovery. If you aren’t sleeping 7.5 hours minimum, you are going to have big performance and development issues as an athlete, I can guarantee it! Improving your sleep to at least this amount per night will be one of the best things you can do for your training. For me this involved, to my despair, completely quitting caffeine for good.
• Improve Diet – Pretty obvious but you need to be eating huge amounts of protein first and foremost. Most athletes don’t get enough. Secondly, fast-twitch muscle fibers are extremely carb hungry tissues and you must be getting enough quality carbs in everyday. You should be eating super clean to avoid inflammation also.
• Reduce Inflammation – Goes back to diet largely, but if you’re able to reduce overall bodily inflammation, your muscles stand a better chance at recovering more quickly.
• Reduce Training Volume & Frequency – I’d say there’s no good reason to be in the gym for longer than 2.5 hours a day, five days a week. That’s 10 hours a week max. Now, you can do low intensity stuff like mobility and light cardio and whatnot on top of that, but your actual lifting and jumping should be kept to 10 hours per week total to allow adequate rest.

If you focus on those four things, you’re going to see some absolutely ridiculous gains.

Seriously, less is more!

3. Rate Coding & Your Lack Of Neural Efficiency

Your current psychological state when performing a movement has a large effect on how well you’re able to recruit muscle fibers to complete a task.

Rate coding allows your muscles to develop more force by enhancing the frequency at which the neural signals get sent to your muscles telling them to contract.²http://www.higher-faster-sports.com/psychofactor.html

It is possible to manipulate your mental state to such a degree that you’re able to produce a significantly superior performance than if you are in a more relaxed state of mind.

For instance, when Eddie Hall became the first man to deadlift 500kg, the heaviest he’d ever lifted beforehand was only 463kg.

That’s a 37kg PR which is absolutely unheard of!

But if you listen to him talk about how he was able to achieve this incredible feat of strength, he’ll tell you his success was largely because of his mental training going into the lift.

For months he was training his brain to activate muscle fibers more efficiently.

This enabled him to become more neurally aroused and produce a lot more adrenaline going into his record breaking lift.

The environment you’re in when you’re testing your vertical jump will play a big role in rate coding and adrenaline production.

If you’re jumping in a quiet, empty gym, you simply won’t produce the same adrenaline as you will before a grand final basketball game or if there’s a cute girl watching you.

If Through Fire & The Flames is playing super loud and all of your mates are cheering you on as you attempt to set a new jump record, you’ll almost certainly jump higher than you would alone in a quiet environment!

So if you’re wondering why your vertical jump went down, maybe it’s just because you were way more amped up last time you tested it!

4. You Stopped Training For Too Long

Not much to say about this…

If you stop training for an extended period of time, your body starts to lose muscle memory and becomes less efficient at the activity over time.

Now if you took a really long break from training, several weeks or longer, of course your jump is going to go down. What do you expect to happen!

Deload Weeks

After an intense training block of 4-6 weeks, it’s a good idea to take a deload week. This can vary but typically you’ll want 5-10 days of greatly reduced training volume to allow your body to fully recuperate.

Think of it as taking one step backward to allow yourself to take two steps forward.

If you don’t include deload periods in your training, you almost certainly will develop a degree of chronic fatigue in your body which will inhibit your long term vertical jump gains.

You should be smart about your deload week and not just sit on your behind for a week straight.

If you literally do nothing for a week, your muscles will actually start to atrophy.

You should definitely do something during your deload, like around 30% of your usual volume is a good place to start.

Keep intensity fairly high.

If your vertical goes down during your deload week, that’s fine. Remember we’re concerned with the bigger picture here and usually you’ll quickly be able to surpass the results you were getting before your deload.

5. You Got Heavier (Fatter)

Body fat is cancer to a vertical jump aspiring athlete.

If you look at all the best jumpers in the world, they’re usually all pretty ripped.

Michael Jordan was said to have had 3% body fat during his career.

He had less body fat than many clinically anorexic patients!

As jumping athletes, we want functional weight, or ‘lean body mass’ which refers to the fat free mass on our bodies.

Fat may have some anatomical benefit in certain sports like powerlifting or strongman, but it has no place wherever jumping is involved.

One of the quickest ways you can notice vertical jump improvements is to lose body fat. If you go from 86 kg to 84 kg over the course of a month, if you did it right, two things will become really obvious to you: chin ups are way easier and you’ll jump higher.

Getting heavier because you gained muscle is a different story. When you gain muscle, you almost always gain strength.

And there is a linear relationship between strength gains and vertical jump gains, for the most part.

Gaining more muscle, up to a certain point, is almost always going to be beneficial to vertical jump hungry athletes because jumping ability will often respond well to that strength increase.

Just be mindful of that ESD, which leads me to my next point…

6. You’re TOO Strong

This is not going to be relevant for almost everyone reading this, but for those athletic freaks who are built like rugby or football players, you may actually risk becoming too strong.

We commonly use squat strength as a measure of maximum lower body force production.

Most jump athletes should aspire to squat 1.5x their body weight at least, otherwise they’re going to be lacking in the strength department.

But for some athletes, achieving those numbers is easy and they’ll go on to squat 2x their bodyweight or more.

There isn’t much other than anecdotal evidence for this, but increasing your squat from 2.5-3x bodyweight likely isn’t going to have a positive impact on your vertical jump any more.

In a few cases, such as in the case of AC Barch Jr, who was famous for his ridiculous squat strength and massive vertical, strength doesn’t seem to be much of a limiting factor on vertical jump height at all!

But for most people, it will. You’ll simply get too big and heavy and you’ll struggle to use all that force effectively (bad ESD).

It’s pretty common that once you get up over 2x-2.5x bodyweight in the back squat, you’re getting close to that ‘too strong’ territory.

At this point the limiting factor for your vertical jump is almost certainly no longer total strength, but rate of force development.

Remember you have to be super mindful of that explosive strength deficit.

If you’re increasing your squat heaps but your vertical jump is barely increasing, you’re increasing your ESD and if this remains consistent over several months, you should shift your training focus from strength to RFD training.

In 95% of cases, this isn’t going to be something people have to worry about.

Most people don’t squat anywhere near 2x bodyweight and can always benefit from getting stronger in the gym.

Conclusion

By far the biggest takeaway from this article should be to ensure you are not overtraining.

I know it can seem like if you’re working out 20 hours a week that there’s no way you could be overtraining, but you almost certainly are.

You probably won’t feel like you’re overdoing it either. You might feel just fine.

But I guarantee you if you’re taking your training seriously and not getting the results you want, it’s almost always a better idea to reduce volume than to increase it.

If you’re not looking after your diet and sleep as well as you should be, you’re doing yourself a massive disservice.

It’s so easy to correct and will produce a much higher ROI from the time you are spending in the gym.

Lastly, don’t be concerned if your vertical goes up or down a bit from week to week.

That’s normal.

Just look for a gradual improvement over the span of months.

It’s also a good idea to keep an eye on your explosive strength deficit and use that as a guide for your training focus.