Performance Tips: Nutrition

Writing nutrition and weight management books is a multi-billion dollar industry. To begin, approximately 60% of the Caloric energy from the food we eat is lost as heat during the fabrication of ATP (adenosine triphosphate), the high energy, intermediary molecule actually used by the muscle cell to power muscle contraction. Additional energy, again reflected as heat production, is lost when ATP is metabolized in the actual mechanical work of muscle fiber contraction. The net result - only 25% of the Caloric energy in the food we eat is actually used to power the muscle cells. The initial heat loss associated with the conversion of Calories in food into ATP occurs slowly over several hours and is easily compensated for by our body's temperature control mechanisms, but the heat produced with the metabolism of ATP to power muscle contraction is concentrated over a shorter period of time and is why our body temperature rises (and we sweat to compensate) when we are exercising.

So, here are a few things I have learned from research or from my own experience:

Pre Ride

• Don't eat anything within an hour of the ride. If you leave less time, you will sabotage your blood sugar with an insulin reaction. An hour leaves enough time for insulin and glucose levels to return to normal, but leave more for solid foods and even more for hard-to-digest proteins and fats.



• Remember that you have a reserve of 2000-3000 calories of glycogen before the majority of rides (depending of course on the time between physical excertion);



• Side bar: Trained muscles store more glycogen within each cell than untrained muscles, expecially if they have trained for high-intensity work; further glycogen breakdown occurs more slowly in conditioned cyclists, relies more on fat for energy, so that glycogen can last longer.

During Ride

• Don't eat anything for the first half hour of the ride



• Start drinking in the first 15 minutes of a ride.



• Eat often instead of in big lumps



• Drink one large water bottle of 750 mL or 24 oz per hour of riding. Nearly every calorie of heat you produce must be dissipated by evaporating water from your skin, which adds up to tremendous volumes for replacement. Water is especially vital in hot or dry weather, or when at altitude.
  
  
• Drink more water than you think you need. By the time your feel thirsty, you are already dehydrated! Even Lance Armstrong is reminded to drink a lot during his rides as he confessed during a 2005 Tour de France interview.



• There is no physiological reason to save water for later. Your body will sweat just the same whether you drink now or save those swallows for later, and you're not changing the weight being moved around either.



• Losing as little as 1-2% of your body's water volume can impair cycling performance by 5-15%.
  
  
• Consider energy drinks. If you carry two water bottles on your bike, try filling one with the energy drink and the other with plain water. The water helps the sports drink goodies be absorbed quicker.



• Plan ahead. Know where you can stop for water on your rides. Know where you can buy more food on your ride, and bring a few dollars with you. Sometimes that extra energy bar will make all the difference.

Post Ride

• As soon as you can! Even minutes count in reclaiming your gylcogen stores (see below).

Pre Ride

• The meal before a ride should be low in fat and with no big lumps of protein. Both will tie up body resources in digestion, resources which are really needed for powering your legs. Also, cut down on fiber, which will absorb water and sit in your stomach. This is the only time where you don't want fiber in your system.



• Eggs are a terrible choice, and milk is a poor beverage. Pasta, potatoes, fruit juices, breads, or pancakes are great pre-ride meals, while whole-grain cereal with milk is much less so.



• Fiber in the digestive tract attracts water out of the blood and can cause stomach discomfort during performance



• Drink at least 8 oz of water right before your ride.



• No "Carbo loading". Carbo loading does not mean eating a big pasta dinner the night before. Rather, it is a program which attempt to temporarily increase the muscles' appetite for stored glucose by completely draining them a week before the big race, teasing them for a few days with a low-carb diet, and spending the last couple of days pouring on the pasta. Carbohydrate loading doesn't always make you ride faster, and it is easy to screw up. Further, there are negative side effects, such as overall tightness, bloody urine, and cardiac abnormalities which could lead to a heart attack.



• Some say you should eat foods that are low on the Glycogic Index as a pre-ride meal and others explain there is no evidence of this.



• No heavily sugared drink minutes before an event. Within five to seven minutes, the sugar enters your bloodstream, increasing glucose concentrations beyond what your body will tolerate. Your body's response it to dump insulin into your blood, to neutralise the sugar. This would be fine if the glucose was all stored as gylcogen in only the quadriceps, but the blood is drained of energy to stock up the arms and back with non-transferrable glycogen. Meanwhile, your blood sugar is lower than before, and the insulin interferes with using fat for energy. Not a pretty picture. We'll learn that sugar goes directly to working muscles -- I said working muscles.



• I'm giving away one of my "trained" secrets for the low introductory price of . . . a glass of water. Keep this fact in mind when preparing for your next event: frozen water is 9% lighter than water (which, as you may have guessed, why ice floats on water). So, freeze water in your water bottle right up to the point of your ride (just freeze one bottle of course or you'll be squeezing like Superman/woman in the first 15 minutes). Not only are you lighter (for a bit) but you are also enjoying a cold drink for a longer time.

During Ride

• Pick Foods that are on the high-end of this scale during your ride. The glycemic index rates the speed at which various carbohydrates are metabolized and their ability to raise blood sugar. Foods that rate high is the list make their energy available after twenty minutes or so, while foods which come in under 35 provide sustained energy. Glucose is the reference point, with an index of 100.

  Sugars
  Glucose	100
  Honey	73
  Table Sugar	65
  Starches
  Instant Rice	90
  Corn Flakes	84
  Graham Crackers	74
  Cheerios	74
  Bagel	72
  White Bread	70
  Bran Muffin	60
  White Rice	56
  Oatmeal Cookie	55
  Popcorn	55
  Brown Rice	55
  Spaghetti	41
  All-Bran	42
  Rye	34
  Barley	25
  Fruit
  Watermelon	72
  Raisins	64
  Orange Juice	57
  Banana	53
  Orange	43
  Apple Juice	41
  Pear	36
  Apple	36
  Grapefruit	25
  Plums	24
  Cherries	22
  Vegetables
  Baked Potato	85
  Corn	55
  Sweet Potato	54
  Chickpeas	33
  Green Beans	30
  Lentils	29
  Kidney Beans	27
  Peanuts	15
  Dairy
  Ice Cream	61
  Skim Milk	32
  Yogurt	14

• Other than those listed, my favorite is a good ole Fig Newton (Carbohydrates: 65 %; Fat: 18 % Protein: 3 %)



• Here are some home made energy bar ideas



• Fluid (Glucose) replacement during ride. Fluid replacement to the tissues from beverages containing up to 10 per cent glucose is rapid (Davis et al., American Journal of Clinical Nutrition 51(1990): 1054-1057). Less than 6 per cent may not enhance performance, and more than 10 per cent may cause abdominal cramps, nausea, and diarrhea. With this in mind, look at labels and water some sports drinks down.



• Water is the best fluid to drink! It is recommended because it rapidly leaves the digestive tract to enter the tissues where it is needed.



• Glucose goes directly to the working muscles during cycling. So, don't worry about packing on the pounds of sugar; it is used immediately and by cycling more this increases your muscle sensitivity to insulin so that the muscles become the primary recipient of blood glucose.

Post Ride

• High carbohydrate meal eaten within 15 minutes after physical activity accelerates the rate of glycogen storage by 300 percent. After two hours, the rate of glycogen storage declines by almost half. (Ivy et al., Journal of Applied Physiology 64 (1988): 1480-1485)

Roles of Vitamins and Minerals in Exercise are highlighted below (keep in mind that it makes no sense to "feed up" on these vitamins before an event as these vitamins and minerals are more of a lifestyle than an eventstyle measure):

Vitamin or Mineral	Function
Thiamin, riboflavin, niacin	Energy-releasing reactions
Vitamin B6, zinc	Building of muscle protein
Folate, Vitamin B12	Building of red blood cells to carry oxygen
Vitamin C	Collagen formation for joint and other tissue integrity; hormone synthesis
Iron	Oxygen and energy metabolism
Calcium, vitamin D, A, phosphorus	Bone building; muscle contractions; nerve transmissions; component of high-energy molecules
Sodium, potassium, chloride	Fluid balance; transmission of nerve impulses for muscle contraction
Chromium	Assistance in insulin's energy-storage function
Magnesium	Cardiac and other muscle contraction; energy-releasing reactions

(This is just a sampling; others play a role as well, taken from Whitney and ROlfes, Understanding Nutrition)

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Curt Austin has put together a nice calculator to estimate power output (in Watts - you enter your own parameters) on his website. As energy used in Watts is directly proportional to Calories, this calculator will let you play with the numbers for weight, position on the bicycle, road grade, and air resistance/wind which we will discuss below.

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