Fuel Your Engine

17 12 2009

It’s a wonderful thing when a successful training and racing effort combine to form a podium finish. In order to get there, I think that there are prerequisites for success, namely an organized training program, proper equipment, sufficient sleep and recovery, appropriate racing strategy, and the right food. I’ll talk a bit about what I’ve learned on how to fuel or feed my cycling engine. Let’s break the nutrition category down into manageable components: fluids, calories, carbohydrates, protein, and fat. Keep in mind that a balanced diet is a must and the following topics only address particular parts of my food intake.

Fluids– My body is 60-70% is water, and I know that if I don’t keep myself hydrated, my performance will suffer. I learned that to estimate my sweat loss rate, I must weigh myself before and after the ride. After adjusting for any drinks taken during the ride, roughly every 2.2 lbs. of weight difference represents 33.8 fluid ounces of sweat loss. The idea is to limit my weight loss to <1% of my initial body weight by drinking enough fluid. My water bottles are about 24 fluid ounces in volume. Since I continue to lose water after the ride, I should plan to consume 1.5 times the volume of sweat loss. For me, the best drink mixture to use seems to contain at least 75 mg of sodium per 8 ounces, and a carbohydrate concentration of about 2 to 8 percent.

Calories– This category is difficult to quantify without accepting approximations. My Sigma Sport PC14 gives me two parameter settings that I can use for cycling. “55” is for average cycling at 11

Sigma Sport PC14

mph and “80” for intensive cycling at 17 mph. It would be nice to see some wattage figures utilized instead of mph but I know they wrote the manual for the masses. Nonetheless, the lower figure works fine for a recovery session when my wattage is <148 and rpm is ~90, that’s around 11 or 12 mph. The other is good for an endurance miles session when my wattage is 149 to 200 (~187), and my rpm around 100. This shows my speed at 16-17 mph. Any efforts in a higher power range for any duration will skew the caloric estimate. For instance, I wouldn’t have confidence in the caloric estimate after completing power/interval training. That’s about it for measuring calories with this instrument, but I really use it to monitor my heart rate, and for the last two years, it’s performed flawlessly.

Knowing my baseline metabolism is important too, because that’s the amount of calories I burn just sitting here breathing and typing. I understand from general reading that the Mifflin-St. Jeor equation is more accurate to use than the Harris-Benedict equation. So, when I estimate my activity level at Fitday.com, I get 1,684 calories per day. Any calories burned by my training activity must be replaced by food,and thus my total daily requirement is base plus activity equals total intake of food. Since I started tracking these numbers, the range appears as 2,817 to 4,224 kcals. Monitoring this stuff can drive your family nuts so be sure to explain why you’re fanatically reading labels, mumbling to yourself, and turning the pantry upside down.

At any rate, Fitday.com allows me to monitor my food intake calories and activity calories for trends that I need to address. NutritionData.com lets me enter the recipes I like to cook from and determine the nutritional construct. I’ll take this information and add it to my meal sources in Fitday, which makes it easy to keep tabs on my daily intake and adjust if need be. Fitday.com has many report formats that allow me to summarize data over time.

Sample Food Intake Format

Sample Activity Format

Carbohydrates (CHO)- The body is somewhat like a hybrid car in that it uses more than one energy system. Like the auto that has an internal combustion engine and an electric motor, the body utilizes the ATP/CP, aerobic, and glycolytic energy systems to power it’s muscles. The ATP/CP system provides quick power at very short bursts–less than 10 seconds, the primary system or aerobic system provides the majority of the power–most of the time, and the glycolytic system, which provides supplementary power when demand exceeds the aerobic systems ability to supply. The body as a macro-system uses these energy engines in combination based on demand. Now that I know what systems provide the energy, I can think about how to go about keeping it fed.

I find many sources, JeukendrupBurke, and Carmichael who recommend that CHO comprise about 60 percent of my diet. I found the tough part is to add smaller meals throughout the day in order to meet the percentage objective. For example, my base calorie requirement is 1,684 x 60% = 1,010 calories in CHO. I have to add the CHO calories from the lone activity–737 x 0.60 = 442. Total estimated CHO intake would be 1,010 + 442 = 1,452. Here’s what my Fitday tracking report shows me:

Sample Breakdown Format

I overshot my estimate of 1,452 with 2,115. Additionally, that 69% should be closer to 60% as an indicator.

Another path is daily intake based on weight. I weigh-in at 77 kg. Jeukendrup recommends 8-10 g/kg for daily intake. For me, 77 x 8 = 616 to 770 g per day. Using this scale and observing the 525.1 in the table above…I’m short of my target. Burke similarly recommends 7-10 g/kg per day, as sufficient to replenish CHO stores. However, he also states that an intake over 5 g/kg will not accelerate glycogen replacement after exercise. I accept that hitting the exact number is not the goal. All I need to do is get close for the high-majority of the time. What I usually do is to start with breakfast (my favorite meal), oatmeal or similar, eggs, soy milk, and fresh fruit/smoothie; make the entries in my log and continue monitoring. As I proceed through the day, I note burn rates of activities and how much of a gap I need to close to meet the targets. I’ll adjust my food intake as needed.

During sessions on the trainer I ensure to take on the recommended concentrations of fluid and CHO. Once I finish the session, I’ll immediately continue with stores replenishment, working into solid food easily within an hour. Meals are usually created in the first place with re-fueling in mind, allowing fast induction after the ride or workout. As an aside, I like to cook Italian cuisine, which contains many pasta dishes and opportunities to meet caloric requirements, not to mention it just plain tastes great.

I shouldn’t forget to mention that “glycogen window” of replenishment after training or racing. The body replenishes glycogen stores at the most receptive rate starting with the end of exercise and declines thereafter. Here’s my understanding of how various sources define the window and respective desired intake rates (per hour):

  • Jeukendrup
    • immediate to 4 hours- 1.2 g/kg of body weight (for me 1.2 x 77 kg ~93 g)
    • 12 to 24 hours- 8 to 10 g/kg of body weight (for me 616 to 770 g)
  • Burke
    • as soon as possible to 2 hours- 1 g/lb of body weight (for me 1 x 171 = 171 g)
    • 2 to 4 hours- include a ration of 1 protein to 4 CHO, CHO calories comprises 60% of caloric requirement
    • 18 hours- 3 to 5 g/lb of body weight (for me 513 to 855 g)
  • Carmichael
    • as soon as possible to 30-minutes- start with 50-60 g of CHO
    • 1 hour- (spread the total CHO intake quantity)
    • 2 hour- (spread the total CHO intake quantity)
    • 4 hours- 1.5 g/kg of body weight (for me 1.5 x 77 kg ~116 g)

I’m getting better at following the above recommendations, but I really should press myself to do it by these numbers . I’m close though.

There are many sport drinks and mixes out there, what do I drink? For training sessions I like a drink mix that supplies carbohydrate in the form of glucose, sucrose, or maltodextrin (they’re oxidized at higher rates) with a volume of 2 to 8 percent. During outdoor rides or racing, I’ll use a mix that includes the former, but also contains electrolytes. The Gatorade Thirst Quencher mix I use contains about 304 mg of sodium per 24 fluid ounces (~0.7 liter). The Hammer Sustained Energy mix is a bit less generous at 112 mg per 24 fluid ounces. It seems that both of these  do not meet the recommendation of 400 to 1,100 mg of sodium per liter. Some is better than none in this case.

Protein– My target for protein intake is 1.4 g/kg or 107 g per day. If I consider the 60/20/20 diet breakdown, 3,026 calories x 0.20 percent = 605 calories from protein is required. Both Fitday targets are satisfied, and I’ll consider myself on the right track. Studies have shown that the coingestion of protein and/or amino acids increases the rate of glycogen synthesis by 40 to 100 percent and by 30 percent according to Burke. However, another study shows that the inclusion of protein does not increase the synthesis rate when the CHO intake is high (1.2 g/kg of body weight) and provided at regular intervals. My bottom-line is to cover the base, if I don’t accomplish my target intake, then it makes sense for me to include protein.

Given the desired ratio of 1 unit of protein to 4 units of CHO, another challenge for me is to keep the protein units at or under 25% vs CHO, otherwise reduced gastric emptying will slow re-hydration. I should remember to “do the math” when preparing the next meal or snack.

Fat– I know what it is and I have too much of it. Just joking. In October, I weighed-in on a Tanita Ironman scale with a good hydration level (>60%), I was 7% body fat. Later the same month, another hand-held impedance device gave me 13.7%. Readings are all over the map. Still, why haul it up a hill when you don’t have to? I weigh myself the same time every morning, log it in my training manual and also at Fitday.com so I can monitor the trend line. The elite and world-class cyclists have body fat percentages from 5 to 8 percent, but there’s a world of difference between their training program and mine. I don’t worry too much about this component. I’m sure that my diet statistics show that my mean is <20% calorie-wise, so this likely contributes to the difficulty of ingesting  the higher of 2,000-4,000 calories a day.

My weight trend line has a positive slope over the last four months. To me, this indicates that I’m trading fat content for muscle tissue because I’m usually in a negative energy balance as indicated here:

Sample Burn Rate Format

Sample Weight Trend Format

That was a lot of information and I hope I interpreted the various authors correctly. At any rate, there’s plenty of information out there and the more I read, the better I understand the subject. I hope you enjoyed reading the above information. Please send me any questions that you may have, I’d love to discuss them with you.

Got a high-performance engine? Better put the right fuel in it!


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