Tuesday, 30 July 2013

There Or Thereabouts

One of my other little holiday experiments involved carbohydrate deprivation for two weeks as part of a carbohydrate intolerance test recommended by Phil Maffetone in his Big Book (my holiday read). The idea behind the test is to severely restrict carbohydrate intake for 2 weeks (no high- or moderate-glycemic carbs, no fruit even) and assess the impact on physiology, energy levels etc. before gradually weaning myself back onto various carbohydrate sources and assessing their impact to see if they have an adverse effect (e.g. wheat). Dr Maffetone swears by this test citing it as
"the best way to jump-start your metabolism because it quickly shifts the body into a higher fat-burning state." and that "tens of thousands of athletes have used it as a necessary platform to get healthy, lose body fat and significantly improve aerobic function and overall endurance."
Before I had finished the sentence I had started my very own two week test, ignoring the recommendation that "The two week test is best performed during your aerobic base period"
To assess "before conditions" I should have completed a 5 mile aerobic test at my 138 MAF (Maximum Aerobic Function) Hr. As I was nowhere near a track I skipped this. In any event, I had my doubts that I could improve my aerobic function, given my recent form. Still I was excited to see what the impact would be. The first few days to a week were not too bad, but as I entered the second week I was getting a bit weary of the diet (plenty of eggs, nuts/nut butters, cheese (unprocessed) meat and vegetables) which was quite repetitive, and I noticed an increasing craving for sugar. I came off the deprivation yesterday and can confirm that sugar coated crusty raisin loaf has little or no impact on my physiology or energy levels, apart from the fact that  I found it difficult to stop after 3 or 4 slices.
 In fact the biggest impact of the whole experiment was the complete lack of energy for the first few miles of most of my runs, some of which were well above 9 minute pace. However I was equally surprised at how well my energy and pace picked up after I got over these 2 or 3 opening miles - one on the main recommendations of Dr. Phil is the 10 to 15 minute warmup/cooldown starting and ending at walking pace, the point being to gradually ramp up from your standing Hr (say 70) to your exercising aerobic Hr (say 130), which is the most efficient way of mobilising your limitless fat stores as a fuel source and minimising the burning of your finite reserves of carbohydrate fuel. The longer the distance the more important this becomes (e.g. the 6 mile cut-in approach to marathon racing).
As my next race will be nearly 4 times marathon distance, mobilising the maximum ratio of fat/carbohydrate fuel mix from the off is probably the single most important thing that will ensure I have the best chance of finishing in a decent time as the aim is to stretch my carbohydrate resources (preloaded and what I can ingest during the race) for a long as possible as I can't burn fat on it's own (fat is like the log to the carbohydrate flame - if there's no flame the log is feck all good to you) - and I don't want to spend the last 20 miles crawling on all fours burning the very muscles I need to get me to the finish line.
Jamie's post last week gave the best analogy of how I think our fat burning engines work most efficiently (although his analogy was on consistent training) - that of a big heavy ocean freighter that takes an age to build up speed, crawling along even at full throttle until it reaches its cruising speed which it can maintain forever, even if you ease back a little on the throttle - solid, dependable, reliable, enduring - granted there's no sprint finish with this engine.
I don't expect to feel as lethargic at the start as I did during my "carb depleted" runs. I was lucky that one of these runs - pacing the 3:30 group in the Killarney Marathon - started with a net 5 mile downhill section, which helped me ease into the effort without too much trouble, although the warm day proved challenging, with Tony (my fellow pacer) and I coming in alone, having lost our last pacees before mile 20 - 18th out of 212 finishers in a time of 3:29:33
I finished off my 2 week experiment with a 5 mile MAF test at the track this evening, with the results showing little change over my previous 2 tests in March and May. The slight dis-improvement since May, is probably within the margin of error of my Garmin HR monitor.


  1. I'm not particularly surprised by the result - your aerobic engine was already developed to an amazing degree. That also happens the reason why I never did the 2 weeks test myself (I might have changed my mind had you reported a big improvement - not before Connemara, obviously).

    That's still a very impressive pace for that HR, mind.

  2. did your body weight stay the same Grellan?

    1. Actually Keith I meant to say my weight dropped by about 3 kg from 77 to 74kg, which is dramatic enough over 2 weeks - a lot to do with the fact that the body retains more water when consuming carbs and storing glycogen. It has bounced back by 1 kg already.

  3. I'm just up to that section in the Big Book. Yes, I'm a slow reader. Agree that getting the tanker engine up and ticking over at minimum revs is half the secret of ultra success. The other half would be maximum tolerance of maximal pain ;-)

  4. You are one fit guy not just in the sense you obviously run a lot but in the real sense of fitness - efficient use of energy, low HR, quick recovery times and so on. I think this ultra is made for you