Sunday, 27 September 2015

LCHF and endurance riding - Part 3

LCHF adaption can play a huge part in endurance performance. By reducing carb intake you reduce the insulin loading and allow the cells to better absorb and metabolise fat. But this takes time. It's not an overnight switch. It can take weeks or months. Once you are adapted, a byproduct of all the extra fat metabolisation is the production of excess ketones which the brain is happy to feed on.
It stands to reason that if you are able to metabolise fat and produce ketones you don't have a deadlock where the two key components of performance, namely, muscles and your mind, are competing for the same resource.
In practice, since adapting the LCHF lifestyle, I have had instances where I have maxed out physically due to poor training but have never had the mental collapse normally associated with bonking.
In multi-day endurance events it is unlikely that you function in an elevated heart rate zone for an appreciable time. It general you have short bursts of elevated heart rate effort.
My question, to which I have no answer to as yet, is as follows: once you are several days into an endurance race how is your exertion in terms of HR zones defined. Are the zone HR rates remain at the rested state zones or does it shift down as your condition declines and your heart rate follows?
I must point out that hearts don't get tired in the sense that your heart rate drops because that organ get exhausted from the exercise. Sure, the heart is a muscle and does get stronger with exercise. As a conditioned athlete athlete your heart rate is defined by the oxygen demands of the body. If you recruit significant muscle mass you need more oxygen and your heart responds by delivering more oxygenated blood to meet the demand. That being the case, it follows that your HR Max is particular to an activity. Swimming, running, cycling and cross-country skiing will yield very different results.

We will assume that our endurance efforts take place in a lowered heart rate effort which facilitates aerobic metabolism. That being the case you are well within the fat burning exertion zone so should have sufficient fuel in the form of fat to supply your energy needs.
A quick word about carbohydrate and fat reserves. The tried and tested method of carbo-loading before a big event will store away only 5k calories of race fuel reserve. Probably enough for a 5 or 6 hour ride. Our body fat stores in excess of 80k. And that's a super lean athlete. I probably have twice that tucked away.

Yesterday I completed a 38 hour non-stop bike race and burned something in the order of 22k calories. If I wasn't fat adapted I would have run out of steam very quickly. I would need to keep fuelling on carbs to keep pace with the rate of burn. As it was, I hardly ate anything and finished the race firing on all cylinders. As a rough estimate I would think I ate food somewhere in the region of 6-8k of calories. Huge deficit if not fat adapted.

So, the bottom line — what do I eat while racing in multi day endurance events. The short answer is "anything". I used to like a mixture of Coke and water in my bottles. Off the bike I never drink Coke. On the bike I used to like it. When I started the most recent race 2 days ago I put Coke and water in my bottles and I didn't enjoy it like I used to. I eventually switched to just water. I added the occasional sachet of electrolytes or use the effervescent tablets that do the same thing. But I got sick of that taste and made a point of drinking that separately and keeping plain water in my bottles. I used to eat gelatine based soft chews; jelly babies and wine gums. I managed to get through just one roll of wine gums. I took snack bars and a handful of nougat based race snack bars and didn't use any of them. I seems I have gone off sweet things completely.
I just want normal food. I had a hamburger and didn't eat the bun. Not my cup of tea it seems.
Does it work? I won the race. That's sufficient evidence.

Given the nature of the races I do it is an impediment if you are on a strict diet. I eat whatever I can get my hands on but choose LCHF options if they are available.
To be fair, I haven't done any events in excess of four days since switching to LCHF so have no experience of what the effects are of dropping out of a fat adapted state due to an increase in carb input. My experience in events up to 4 days is that my metabolism doesn't appear to change in any noticeable way.
To wrap this up let's look at the incident of 2010 where I bonked an hour into day 2 of an event and compare it to the race I did in June this year without training for.
In 2010 I wasn't on LCHF and did the normal carbo-load thing. Clearly it didn't work. I was trashed and my mind went tilt. In June this year after a 3 month layoff due to injury I was a last minute entry in a 500km race. 8 hours in my lack of condition was evident. But my mind was as sharp as a pin. I knew exactly what the challenges were and managed to deal with the issues and went on to win the race. That I think is a big difference. If you can keep your head space intact you can deal with the issues. By being fat adapted I think bonking is a thing of the past. I can't make that statement with absolute surety but can say I haven't bonked since switching to LCHF.

1 comment:

Leon Kruger said...

Hi Mike. An excellent article. This is exactly what I have been trying to tell my fellow cyclists but have not been able to express myself as well as you have just done. I'm by no means in your league but participated in the R2C (where I saw you on the last night), the R2R in June and last week the SR2R. And all were done on the LCHF diet. I'm turning 62 next week and have never felt this good during endurace events. Last week I tried explaining to a fellow SR2R rider that I dont "hit the wall" anymore. Maybe he will read this and understand. I'm paid up for RASA16 and will be able to compare my LCHF performance against my RASA14 experience when I was still a sugar burner. BTW Congrats on your Durban Dash Up win.