What is Bonk Training?

There is a phenomenon known as “bonk training”, which is followed by some very fit athletes. It is not wise if you’re just starting out. Bonk training is controversial. In fact, in the course of normal training most aesthetes takes steps to safeguard against bonking.

Bonk or bonking refers to the point when glycogen stores are depleted. Cyclists call this bonking, endurance runners call it hitting the wall. “Bonk training” is an exercise program designed for weight loss. Bonk training burns more fat and may improve training adaptations and fat burning.

What’s the Science on Bonk Training?

Bonk training appears to have some scientific support. Exercise scientist, Bente Klarlund Pedersen, Ph.D., from the University of Copenhagen, Denmark suggests that athletes, particularly endurance athletes, are able to improve their fitness by completing some workouts in a glycogen-depleted state and some in a glycogen-replete state.

The premise for Dr Pedersen’s suggestions is Interleukin-6. IL-6 is a substance that plays a vital role in the body’s response to tissue stress and trauma. Exercising triggers its release and it is thought to facilitate numerous adaptations to exercise training such as increased fat burning, increased resistance to muscle damage and improved cognitive function. So what’s her point? Dr Pedersen suggests that the main trigger for IL-6 release during exercise is glycogen depletion (bonking). Therefore, bonk training results in greater training adaptations (due to IL-6) than training in a glycogen-repleted state.

So the question is should you bonk train or exercise in a a glycogen-replete state? Well, each has advantages and disadvantages. Consistently bonk training is disadvantageous, and the best training strategy will probably involve a combination of both types of training.

What Does Bonking Train Involve?

Commonly bonk training involves cardiovascular exercise on an empty stomach first thing in the morning, when glycogen store levels are low, as well as consuming coffee or caffeine equivalent to 2 or 3 cups of coffee and running or cycling at a casual pace (60% of max heart rate) for 20-90 minutes. Glycogen is the only fuel that can supply and support your exercise efforts above 70% of MHR (maximum heart rate). Therefore, when you bonk, your body is forced to dip into your fat and protein stores instead.

The training session is followed by a normal breakfast. Proponents claim this strategy forces the body to “bonk” shortly into the exercise, and subsequently burn more fat to produce energy. It is not clear how medically sound this idea is. Exerting too much energy and “bonking hard,” or experiencing severe hypoglycemia can be dangerous. Bonking may be harmful to your muscles and central nervous system.

Dr Pedersen suggests another method of bonk training. She suggests to perform two workouts in one day. One in the morning, one in the afternoon. Complete the second workout within hours of first workout, such that there is not enough time to replenish your muscle glycogen stores between workouts and without re-fueling with sports drinks and gels.

How Will You Feel While Bonking?

Since bonking refers to when your body runs out of fuel or you become hypoglycemic, it does NOT feel good. Some of the symptoms include those of hypoglycemia:

  • general weakness
  • dizziness
  • confusion
  • nausea
  • slowed pace
  • fatigue
  • lack or, or no, power
  • irritability
  • When the brain is starved, it may misrepresent incoming images, such that you suffer hallucinations. Instead of seeing rain drops you might something entirely different. Needless to say, it becomes somewhat more dangerous when you can’t see what’s going on, especially when you’re on a bike.

In Triathlon Revolution: Training, Technique, and Inspiration, Terri Schneider writes this: Some people working through a bonk can keep going by basically shutting down their brains and plowing forward. It’s no pretty to watch – and generally makes for an experience you wouldn’t wish on your worst enemies.

Basically, leave this one to the pros.

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