Calculating food requirements

littledove44
littledove44 Posts: 871
edited March 2014 in Training, fitness and health
Is there a proper scientific (ish) method of calculating how much food to consume on a ride of between say four and eight hours?

I think I have all the data, just don't know how to calculate it. I also have the bike calculator app but I read it wasn't accurate for this sort of thing.

Comments

  • phreak
    phreak Posts: 2,910
    I suspect unless you've got a power meter then the answer is no and you'll be relying on general rules of thumb. What does your personal experience tell you about how much to eat?
  • sungod
    sungod Posts: 16,577
    eat properly in the preceding couple of days, have a good meal carbs+some protein 2-3 hours before

    after the first hour riding, plan to average 30-60g carbs/hour intake, start with 'proper' food or cereal bars, save energy gels for later when it's harder to digest solids

    typically a person can digest 50-60g carbs/hour, or with an optimum glucose-fructose mix 80-90g, don't eat more than you can digest, things could become uncomfortable/unpleasant

    keep sipping water throughout, 3-4 times/hour, you need water for digestion as well as making up what you lose through sweating/breathing, if it's hot consider electrolyte replenishment (i like a nuun tablet in the water, but tastes vary)
    my bike - faster than god's and twice as shiny
  • dzp1
    dzp1 Posts: 54
    The maths is quite simple. Work done= power x time. So if you're putting out 200w for 4 hours thats 200 x 4 x 3600 = 2880000J = 2880KJ

    Now the body is about 25% efficient (well probably more like 21-24 but lets use a round number), so the work your body puts in is about 4 times this.

    But there's about 4KJ in a calorie, so they cancel each other out mathematically. You end up needing 2880 calories to fuel that ride :)
  • c40nl12
    c40nl12 Posts: 40
    Read what Tyler Hamilton said Bjarne Riis told him, after a training run he asked Bjarne about how to avoid eating too much,Riis told him, "Drink a big bottle of mineral water and two or three sleeping tablets, and you won't wake up until dinner time,and if you're lucky you won't wake up till breakfast." Genius.
  • shockedsoshocked
    shockedsoshocked Posts: 4,021
    c40nl12 wrote:
    Read what Tyler Hamilton said Bjarne Riis told him, after a training run he asked Bjarne about how to avoid eating too much,Riis told him, "Drink a big bottle of mineral water and two or three sleeping tablets, and you won't wake up until dinner time,and if you're lucky you won't wake up till breakfast." Genius.

    The EPO, testosterone and HGH he was probably pumping into himself may help as well though ;)
    "A cyclist has nothing to lose but his chain"

    PTP Runner Up 2015

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