May 2007 Email Page To a Friend
Your Questions, Answered
Q: I bonked on my first long, hard ride of the year, even though I’m fit, eat right, and was careful to pre-hydrate before I set out? What gives?
—Jeff K. via e-mail

A: First off, I commend you for taking a serious approach to integrated nutrition, hydration, and training. However, your downfall was your body’s inefficient use of fuel. Your body's glycogen operation, your muscles’ main source of fuel, wasn’t ready for what you put it through. From your description, it sounds like you started out okay, but when you continued beyond your usual end point for a ride, your glycogen stores were tapped out. And once those stores are gone, life goes downhill really fast.

This is exactly why a progressive training plan builds up mileage over the course of several weeks. Each week’s 5- to 10-percent increase in miles is just enough to push the body to adapt to the extra work without bonking. What you did, Jeff, was skip that progression, and you paid the price. But here’s the cool part—if you can say there’s anything cool about bonking—I bet if you tried that same ride two weeks after your bonk without changing your diet or hydration you’d probably cruise through those miles without any problem. Why? Your body would now have adapted to this long-term stress and have become more efficient at using its glycogen stores.

Glycogen stores can change to suit the needs of an individual. In your case Jeff, those stores were perfectly adequate to power you through your workouts and rides prior to your big day in the saddle. There’s no reason the body needed to store more glycogen in the muscles. But with your big ride, you’ve shocked the muscles into realizing that they need to store more glycogen because you’re logging more hours on the bike.

That said, there are some things you can do to maximize your odds for a bonk-free experience next time.
  • Go slower when you’re going longer: On a scale of 1 to 10 with 10 being hardest, you want your perceived effort to rate between 5 and 7.

  • Two hours before exercise: Drink 20 ounces (a water bottle’s worth) of sports drink such as PowerBar Endurance. That way you’ll have a reservoir of fluids and glycogen to tap before you head out.

  • 20-minutes before exercise: Top off with 10 ounces of sports drink. You’re just topping off your fluid, sodium, and carbohydrate levels. Doing this delays the need for your body to pull fuel from your glycogen stores a little bit longer.

  • During exercise: Stay hydrated and fueled with an hourly water bottle’s worth of an electrolyte-laced carbohydrate sports drink (PowerBar Endurance) or combination of 10-ounces of water and a PowerGel every 20-30 minutes. The quickly digestible calories from the drink or gel will slow down the rate at which you burn through your critical glycogen stores. NOTE: On hot days, you could need twice as much fluid and electrolytes.

  • As soon as you come home: Down a recovery drink such as PowerBar Recovery to restore your fluid, fuel, and electrolyte levels. You’ll bounce back faster because of it.
Lastly, welcome to the club. This condition has taken down many an elite athlete who ends up tackling a day his or her body’s not ready for. Just chalk your bonk up to experience and realize that it didn’t occur in vain. Your body changed for the better because of it.

By Dean Golich, CTS Coach
Core Strength for Runners DVD

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