Monday, April 21, 2014

Carbohydrate Intake During Exercise

I'm sure you all know that in order to maintain your ability to run or cycle over 90 minutes you must intake carbohydrates. Certain companies who supply carbohydrate powders and gels would like you to take up to 90g per hour.

I'm no expert but I do like to experiment with my training and nutrition. Since October 27th 2013 I have been mostly on a Low Carb High Fat LCHF Diet.

It's great ! Initially on exercise days I ate more carbs especially on days with long and/or strenuous cycles. Lately I have been reducing the amount of carbohydrates consumed on exercise days.

For example, I would consume around 50g carbs on a non exercise days and up to the government guideline amount of 300g on a workout day. ( WARNING: If you follow the governments advice on Carbohydrate intake, you WILL get fat ! )

Now it's around 150g or less more when exercising. I don't even bother with the essential post workout carb intake. I just have protein.

Lets go straight in and look what I did at the weekend.

A 4 hours cycle over 100km

You can see average heart rate is 149 BPM, for me this is classed asTempo (Zone 3)as per my LTHR zones.

 My effort was averaged out as 139 watts which is Endurance ( Zone 2 ). There's always a wee bit of crossover here depending on other factors.

Anyway after 90min I really should have been tucking away up to 90g carbs to keep my muscles going right ? Well no.

What I had was one scoop of High 5 2:1 Energy Source in each 750ml drinks bottle which lasted me the whole four hours. Each serving ( which is two scoops ) provides 44g carbohydrate. So I only consumed 11g per hour. No cramp, no exhaustion.

Ah, maybe I just scraped home before my carb supply ran out. Well luckily I have been monitoring my blood glucose during this experimental period. If I have two Weetabix ( under 30g carbs ) for breakfast my blood glucose after two hours in around 5.5-5.8 m/mol. Immediately after this ride it was 5.8 m/mol.

Wait a minute, if I had consumed all those recommended carbs I would have done a much better job right ?

Let's see.

Trust me, that's the same ride from three weeks ago. Shows how accurate the Garmin is when you look at the Km. Anyway, I knocked 10 minutes off the ride time and with a lower heart rate and power output than in this one.

Food for thought, so long as you keep your carbs lo :)


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