How to Avoid Bonking
By Kevin Murnane
Nutrition before, during and after the ride is all about making sure that your body has the resources it needs to do the ride as well as possible. This can be difficult for intense rides or rides that last more than 90 minutes. What happens if you don’t get enough of the nutrients you need? What happens if you get too much? Before we look at how to go about getting it right, we’ll take a look at what happens if you get it wrong.
Not enough food: The bonk
“Bonking” is what cyclists call hypoglycemia which is the medical term for abnormally low levels of blood glucose. You bonk when you have exhausted your glycogen stores, haven’t ingested enough carbohydrate to produce more blood glucose, and are still riding the bike. Anyone can bonk if they don’t eat properly on the bike. Beginners do it, experienced riders do it, and the pros do it. Depending on the severity of the bonk, it can range from unpleasant to horrible.
Bonking can be especially dangerous for cyclists because your muscles aren’t
the only parts of your body that burn glucose for fuel. Your brain also
burns glucose. This means that not having enough glucose in your blood to
fuel ongoing athletic activity has mental and emotional effects in addition
to physical effects. If blood glucose levels drop too low, the system will
act to protect the brain and will begin to depress glucose use at the
muscles. However, the muscles don’t completely shut down before the brain
begins to be affected and the mental and emotional consequences of bonking
can be more dangerous to the cyclist than the physical consequences.
When you bonk physical exertion becomes very difficult. Your muscles don’t
have the fuel they need to operate effectively and forcing them to work
becomes more and more difficult. You feel extremely weak and lethargic. You
may tremble and shake uncontrollably and sweat profusely. You feel dizzy and
light headed. Your sense of balance is upset. You may have heart
palpitations. You will probably feel hungry. On the mental and emotional
side you will probably feel nervous and anxious. You may become confused and
disoriented. You will have low emotional control and may become hostile,
belligerent and easily irritated. You may experience overwhelming feelings
of hopelessness and of being defeated and unable to go on. Your awareness of
what’s going on around you will shrink and can arrive at an extreme form of
tunnel vision in which the only thing you’re aware of is the spot you’re
staring at on the road in front of you. You may have difficulty speaking. At
the extreme, hypoglycemia can produce seizures and coma.
What do you do if you bonk?
You need to get your blood glucose levels up and
you need to do it quickly. Ingest simple carbohydrates that can be rapidly
processed into blood glucose. The best source for this type of carbohydrate
that you’re likely to have with you on the bike is a sports drink like
Gatorade. Other sources of simple carbohydrates include energy gels (make
sure you drink plenty of water with these), sugar cubes or sweet candy like
gumdrops or jellybeans. Complex carbohydrates like energy bars will take
longer to process into blood glucose and will only provide relief in the
If you catch the bonk early, you can keep riding while you refuel. If you
let the bonk go too far, get off the bike until you recover. You don’t want
to be riding when your sense of balance is bad, you’re disoriented, and
you’re unaware of what’s going on around you.
After you’ve bonked and begun to recover, pay careful attention to what you
eat for the rest of the ride and make sure you keep your glucose level up by
regularly and frequently taking in fast absorbing carbohydrates. Sports
drinks are very good for this.
Perhaps the hardest part of reacting to a bonk is mental. You need to
recognize that you’re not thinking clearly and not being as aware of what’s
going on around you as you need to be to ride safely. Forcibly arouse
yourself from your lethargy and consciously devote effort to paying extra
attention to what’s happening around you. Of course this is easier said than
done; it’s not easy to be aware that you’re not thinking clearly when you’re
not thinking clearly.
Try to get in the habit of monitoring yourself for the early signs of a
bonk. The ride beginning to feel like a chore? Getting irritable and angry?
Not paying very much attention to what’s happening around you? Learn to
recognize the symptoms early and refuel before it gets out of hand.
If you have a regular riding partner whose riding abilities and demeanor on
the bike are familiar to you, be aware of their condition as well. A rider
who isn’t thinking clearly is likely to misinterpret or misunderstand what’s
happening to them in the early stages of a bonk. Help them out. Be aware
that you may have to treat them carefully as they may be experiencing
increased levels of irritability and hostility combined with decreased
emotional control. If you think you might be bonking, tell your riding
partner so they can help you.
As unpleasant and dangerous as bonking can be, the good news is that it’s
easily avoided. Start your clock as soon as you get on the bike and eat
regularly throughout the ride and you’ll never have to experience a bonk.
Eat before you’re hungry, eat before you bonk.
Excerpted with permission from the book, “Nutrition for Cyclists: Eating and Drinking Before, During and After the Ride” by Kevin Murname. Available as an ebook through Amazon.com (www.amazon.com/dp/B00KDJAU12).