Enhancing nutrition to avoid the bonk

The wall, the bonk, whatever you want to call it, it’s what any marathoner fears most. It’s the point at which, no matter how much you will your legs to keep the pace they have, in fact, turned to lead. You cajole and push your body, trying to squeeze any ounce of energy you can but almost to no avail. From here on in, you’re in survival mode.

This phenomenon usually rears its ugly head somewhere between 18 and 22 miles. Unfortunately, I know this from first hand experience :(  And no, it’s not inevitable. If you’ve trained well and properly fuelled before your event, you should have enough glycogen to keep your muscles optimally functioning for about 2 hours. That’s why “the bonk” typically occurs shortly after this point. In order to push that wall further away you have to ensure that your tank is full before you even begin, and that you avoid emptying it during the run. If you find that time and time again you are losing steam in those final miles, the missing link just may be your nutrition.

Studies suggest that in order to ensure your glycogen stores have been maximized, your goal is to consume approximately 7-8 grams of carbs/kg of body weight (or 3-4 grams/lb). Depending on your size, this means you will need to consume anywhere between 350-700 grams of carbohydrates per day. Research has shown that doing this for even just 1-2 days before your event should be enough to ensure your glycogen tank is full.

Reaching this level of carbohydrate intake isn’t easy for most of us. It requires planning and forethought, just as much as you devote to your training. Just to give you an idea of what you may need to eat, here are some examples of foods and their carbohydrate content:

  • 1 large banana, apple, pear                                           30 gms
  • 1 cup grapes or mango                                                   35 gms
  • 1 cup brown rice or spaghetti                                        45 gms
  • 1 cup oatmeal                                                                    30 gms
  • 1 large baked potato or sweet potato                            35 gms
  • 1 cup lentils, chick peas, black or kidney beans         40-45 gms
  • 2 slices of whole grain bread                                            40 gms
  • 1 whole grain tortilla wrap                                                30 gms
  • 1 cup quinoa                                                                          60 gms
  • 1 cup barley                                                                          45 gms
  • 3 mejdool dates or 1/2 cup raisins                                 55 gms
  • 1 cup yogurt                                                                          45 gms
  • 1/4 cup whole grain or rice crackers                               20 gms
  • 1 cup whole grain pretzels                                                  35 gms

It can be difficult to reach optimal carbohydrate levels as you don’t want to overwhelm your digestive system with too much food. I’ve found that the best way to maximize carb intake is to combine sources. For example, a lunch of 2 cups of rice and beans, with some roasted chicken and vegetables, plus an apple can provide 110+ gms of carbs plus lean protein and antioxidant rich veggies. Or snack on a cup of yogurt and a banana for another 75 gms. Adding protein to the mix will slow down digestion, keep you full longer and provide the amino acids necessary for muscle repair and building. You will likely need to eat 5-6 meals and snacks throughout the day and choose wisely. Sure, a slice of cheese pizza can give you 40-50 gms of carbs but it’s also giving you zero in terms of nutrients.

The emphasis should be not only on adequate carb intake but also on quality carb intake. Outside of the immediate pre and post workout window, low glycemic carbs (found in whole grains, legumes, fruits and vegetables) will keep blood sugar levels stable and minimize inflammation. Plant foods that are high in fibre and rich in antioxidant vitamins and minerals will supply the nutrients any athlete needs to replenish working muscles and to keep the immune system functioning optimally. Keeping inflammation down will also improve recovery times and may help ensure nutrient absorption. Keeping healthy and free from colds and flus will allow you to train consistently and thereby improve your fitness and performance.

One special note about fibre: you may want to reduce intake in the 24 hours before a long run or race. While bowel transit time is important for overall health, it’s not something you want to speed up just before an important run :)

Furthermore, electrolytes that are necessary for optimal muscle function are found, yes you guessed it, in fruits and especially veggies. Electrolytes are minerals (primarily sodium, magnesium, potassium and calcium) that help maintain a healthy blood pH, regulate the body’s fluid balance and support muscular contraction. Top food sources for magnesium include leafy greens, bananas, brown rice, nuts and pumpkin seeds; best sources of potassium are bananas, potatoes & sweet potatoes, squash, avocadoes; and calcium rich foods include leafy greens, almonds, dried figs & apricots, broccoli and dairy. Sodium levels can be maintained by sprinkling a little sea salt on your cooked foods, no need to over do it (2 lbs sweat = 1000 mg of sodium which can be replenished with 1/2 tsp of salt).

My own personal experience and that of runners I have worked with has taught me that the most difficult thing with carb-loading is to ensure adequate intake. It requires planning and organization. Don’t assume the food court will have what you need.

The habitual diet of many runners, which often consists of bagels, granola bars, cookies, pizza and gatorade is inflammatory, high glycemic and nutritionally deplete. It will do nothing to enhance your health or your performance. Make good choices, top up your glycogen with quality carbs and reap the benefits on race day!

Next post: how do you keep those glycogen stores topped up during the race?

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