Bonking – What Is It And How To Avoid It

You’re doing a really intense workout, like Insanity, and you’re starting to feel light headed, dizzy and maybe even nauseous.  You’ve been working super hard, but now it seems like you’ve hit a wall and it’s nearly impossible to keep going.  Sound familiar?  I read about this experience once in a while on the message boards and also had it happen to me once during an Insanity month 2 workout.  So why does this happen and what can you do to avoid it?

Signs That You’re Bonking

bonkingBefore we get into too much detail about bonking and the effects, it’s important to outline they symptoms of bonking so that you know how to identify it.  The common symptoms include:

-Feeling slow and weak
-Difficulty continuing your exercise
-Trembling muscles and a loss of coordination
-Feeling light headed or dizzy
-Feeling nauseous

It typically hits you pretty quick too, so it’s hard to miss if this is happening.  It happened to me and it was unmistakable.  I still remember it and it was not a good feeling!

Bonking And Glucose

If this has happened to you, you’re experiencing what has been coined as “bonking“, and it’s pretty unmistakable.  It’s not just a feeling of being tired, it’s more a feeling of dizziness or being light headed.  You definitely know if it’s happening.   It’s most common during long, intense exercises like cycling or distance running, but many people have experienced it during workouts like Insanity as well.  It can be due to dehydration which is very dangerous, but it’s more likely due to levels of glucose in your blood.

In simple terms, bonking is caused by your blood sugar being too low, which is referred to as hypoglycemia.  Basically when you are exercising, you use glucose as a source of energy to fuel your workouts.  There is glucose in your blood stream, but that only lasts a few minutes.  After that’s burned off, your body looks for glycogen to turn into glucose to burn as fuel for your workout.  Your body stores glycogen in your muscles which can be converted into glucose and your liver can also release glucose if needed.  Typically, you have enough glycogen stored up to get through a 90 minute workout just fine, but that’s not always the case.  When you run out of glycogen in your muscles and glucose in your liver, that’s when the symptoms of bonking start occurring.

I think it makes sense why your muscle start failing, but people are often confused about the dizziness.  That’s actually caused because glucose is the fuel source for your brain too.  So when there is an inadequate supply of glucose in your body, it adversely impacts your brain and nervous system.  That is kind of scary and can be dangerous if you keep pushing yourself too hard when you start experiencing these symptoms.

How To Avoid Bonking

So naturally you want to know how to avoid bonking.  After reading this far I would want to know that too!  Basically, it comes down to your nutrition and how you fuel yourself.  The day that I bonked really hard I was confused.  I figured it might have had to do with what I had been eating, so I went ahead and punched in what I ate the previous day into a calorie tracker.   Turns out I only ate 1200 calories the previous day!  For someone over 210 lbs, that was not even close to enough food to fuel my body for a workout like Insanity.

I think that is a common occurrence when people start out.  If you aren’t tracking your calories but are trying to eat less and really healthy, often times people under eat.  They restrict their calories way too much, which doesn’t fuel their body for their workout and can actually be just as harmful as overeating.  That’s why I stress tracking your calories and following the nutrition guides with any workout.  Sure you want to eat at a calorie deficit to lose weight, but you still need to give your body enough energy to get through your workouts.

So if you’re following your nutrition plan, you should have more than enough energy to get through your workout and bonking should not be a problem.  I haven’t run across a Beachbody workout longer than 90 minutes, so if you’re eating right it should not be an issue.  But for some people, they do need to eat a little something before their workout or maybe even during their workout.  Your body might not be as efficient at storing glycogen as others.  So what you can do if you’re still struggling with this is:

-Eat a small pre-workout meal with some simple carbs, like a banana or another piece of  fruit.
-Have small bites of that same type of food every 15-20 minutes during your workout.
-Put a scoop of P90X Results & Recovery Formula in your water bottle and drink that throughout your workout.

Basically you need to fuel your body correctly.  If you’re following your nutrition plan you really shouldn’t have any problem.

You’re Bonking – Now What?

If you’re actually experiencing this as you workout, then there are a few things you should do.  Number one is stop!  Take a break from the workout.  If you keep going you can really put yourself in danger.  The last thing you want to do while working out is cause harm to your body.  So stop your workout if you’re bonking.  After you’ve stopped, then you need to refuel yourself.  The best options here are simple carbs.  Fruit, fruit juice, even candy can work.  Anything with simple carbs that will be processed quickly.  More complex carbs take longer to process and won’t help as fast.  Lastly, drink some water!  So basically, if you’re bonking, you need to stop and refuel yourself.

I hope this article on bonking has been helpful.  I know it’s not fun to experience it, but it’s important to know what causes it so you can avoid it in the future.  I always say it, nutrition is just as, if not more important than the workouts.  Without proper nutrition your workouts will suffer.



  1. […] also referred to as “bonking” during your workout and you can learn all about it here: Bonking and How To Prevent It.  It happened to me, and you can find out more about that experience in the […]

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