As a bit of winter base training, and just for fun, I ran the Bournemouth marathon last weekend. I wasn't aiming at a time, just to enjoy the run, take advantage of the water stops, and to be part of a big event.
Coming out the other side, there were actually some learning points. But first....
A quick word on gait - now that I'm not ramming my heels into the tarmac 40,000 times in 3.5 hours, I found that I recovered incredibly quickly. I can't believe how little damage I did to my legs. I was waiting for DOMS for the next 48 hours, but it never came. So 54 hours after hitting the finish line in Bournemouth, I was running in the club's Tuesday evening 6x800m off 60s session. Sure, I ran the first efforts easy in case something broke, but the last two efforts I was hitting sub 2:50 which is up with my best for this session!
Anyway, this post is more about the nutrition learnings.
The following graph shows heart rate, but I also selected elevation (the thin green line) as it explains some of the heart rate variations.
The very flat sea-level sections represent the flat seaside promenade on Boscombe, Bournemouth and Poole seafronts. The black line is heart rate.
Click on the graph for a full size version!
In terms of effort, that first 4k felt very easy. I was letting people pass me (and I had started in the third pen back), I was chatting, and I hit 4:50/km on average.
Then as you can see, there was a downhill section at 4km, that flattened out. I suspect that the pace and cadence increased, because as the downhill flattens out, you can see that the heart rate raises as I must have tried to maintain the faster pace (the red box). Certainly I was now overtaking people. I remember looking at my watch at about 10k and seeing that the average pace had come down to 4:41/km. From 5km to 21km the heart rate is higher, and as I would soon find out, above the fat burning zone!!
From half way, I was in trouble! 10 miles of burning glycogen had left me depleted. I took a couple of gels from the feed stations (I think about half way and again at about 30 km). At 30km I thought I was going to have real trouble finishing. Walking the two hills had taken their hit on the average pace, and I was down at 4:57/km.
[At this point, I have to confess that in general my HCLF regime is not going as well as it was this time last year (Healthy Fat Low Carb). It's hard work! Autumn 2016 I was frying vegetables and pork belly, I was avoiding all rice and pasta, I was only having one roast potato with Sunday Lunch. OK so I haven't gone back to the muffins 3 or 4 times a week, and I never buy chocolate bars now, so sugar intake is still way down. But I've slipped out of my most efficient fat burning abilities that I enjoyed at the Portsmouth Marathon last December.]
Back to the Bournemouth Marathon. 30km. You can see that the heart rate comes back down (the green box). And this is where I start to recover. I remember, from the 6 marathons I did between 2001 and 2006, when I hit the wall, I REALLY hit the wall. Half Foster territory. Once in London, I had to walk from Tower Bridge to Canary Wharf. But not at Bournemouth last weekend. The wall never came, I think it was about half a mile down the road the whole last half.
This time, I believe I had enough retained ability to metabolise fat that I experienced a bit of a recovery, and the pace never dipped slower than 4:57/km.
Going through the 24mile marker, I realised I had 19 mins left to get under 3:30, and I thought "what the hell". So for the last 2.2 miles I really picked up the pace, bringing the agerage back down to 4:56/km. I hit the finish in 2:29:50!! Boston Qualifier by 10 seconds!
So, although the highest heart rate at which I can run on fat alone has probably come down a bit, the ability is still there.
Not exactly scientific, but I am still enjoying this experiment with a sample size of 1....