Heart rate
2 lurkers |
300 watchers
Oct 2016
8:28pm, 30 Oct 2016
65 posts
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steeplechaser
Thanks for the input SPR & DTD57, my mileage is low because I vaguely follow Furman 3 days a week training, but this year I have failed to do many of the sessions, particularly intervals as I took a conscious decision in May to concentrate more on long runs. I am now looking to try long easy runs rather than Furman pace, hopefully to get a longer term benefit.
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Oct 2016
10:24pm, 30 Oct 2016
521 posts
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tipsku
I've run Snowdonia marathon to heartrate/perceived effort and I got a 25 min course PB, from 4:17 to 3:52. AVG HR turned out to be 170 (max is 193, so that's 88% of max). I tried to keep HR out of the 'red zone' (begins at 175, the HR which Garmin thinks is my LTHR) until about 1h before the finish. I managed that bar two short 'blips' on the hills at miles 5 and 15, reacted to those readings and slowed down to get it back below 175. Then I kept the AVG HR at 175 for the remainder of the race except for the final miles downhill. I found that pacing strategy very effective because I could run the steep hill at Waunfawr from the bottom to the top and felt strong throughout, even had something left in the legs for the downhill at the end. Was very knackered after crossing the finish line and had the feeling that I left it all out there. Very happy with the effort overall and with the strategy. I'll keep doing that in future marathons - staying out of the red zone until 1h before the projected finish, even if this means slowing down more than others on the hills. |
Oct 2016
7:02am, 31 Oct 2016
239 posts
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Dillthedog57
Tipsku - great run, and really interesting how running to HR helped on such a hilly course. I take it your strategy, on a flat course would give you a negative split, or something close to it? Would you alter the heart rates on a flat course?
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Nov 2016
11:35am, 1 Nov 2016
24 posts
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bakedbeano
Gre thread ,just saying hello
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Nov 2016
11:36am, 1 Nov 2016
25 posts
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bakedbeano
OOPs "Great" not gre! Damn these crappy keyboards
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Nov 2016
2:32pm, 1 Nov 2016
12,399 posts
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Dvorak
Very impressive Tipsku, especially given the course profile. I suspect that a lot of people would get better results for themselves doing something similar on less dramatic courses as well. Did you pass a lot of people in the latter stages? Indeed, I reckon that over here http://www.fetcheveryone.com/viewtopic.php?id=10360&page=2166 if damo had heart rate figures available they would show similar, with success following on. |
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Nov 2016
7:57pm, 2 Nov 2016
522 posts
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tipsku
Thanks Dillthedog57 and Dvorak and hello to bakedbeano, welcome to the thread. Dill, you're right, I normally get slightly negative splits with a strategy like that, 1-3 minutes difference between the first and the second half. I would most likely use similar HR limits on a flat course, maybe even slightly lower for the first 5 miles. In Snowdonia the first 5 miles include Pen-y-Pass so I end up with a slightly higher HR than in a flat marathon at that stage. I make up for that with controlling the HR more strictly on the downhill bit to Beddgelert (halfway). So in the end, it results in a similar AVG for the first half. Dvorak, yes, it's like living on the fast lane. From about mile 16, I was no longer overtaken, only overtaking other runners. I checked my stage positions: Pen-y-Pass (4.5 mi): 1017, Beddgelert (13.1): 771, Bwlch-y-Groes (23): 533, Finish: 439 I work with the assumption that if you go above your threshold HR too early, you'll do some damage to your muscles and your fuel storage that you cannot undo unless you slow down significantly. I calculated my calorie needs for the marathon, how much glycogen I can store in my liver and muscles, how many grams of carbs I can take in per hour and what the calorie deficit will be - which will have to come from fat storage. This is why I'm strict with the HR limit in the first half so that I can still burn a certain amount of fat per hour. This will make the glycogen storage last longer, especially in the latter stages of the race. That means that bonking is not an issue as long as I stick to the plan, otherwise it might happen to me, too. |
Nov 2016
3:55pm, 3 Nov 2016
214 posts
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dibbers
tipsku 'I calculated my calorie needs for the marathon, how much glycogen I can store in my liver and muscles, how many grams of carbs I can take in per hour and what the calorie deficit will be' So how do you do this? |
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Nov 2016
11:38pm, 8 Nov 2016
525 posts
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tipsku
dibbers, I had a formula for that which took into account your body weight and then calculated the weight of your liver and leg muscles and then how many kcal per 100g of liver/muscle mass you can actually store. I don't have it with me now right now but I'll dig it out of my notes. I've got it from a marathon nutrition seminar that I attended last year. I can give you an account of what I am doing before a marathon. Caution, long post and some basic maths ahead, proceed at your own risk.  According to the formula, I can store a maximum of 1180 kcal so just over 50% of my total calorie need in a road marathon (about 2200 kcal). In a trail or very hilly marathon where I will run for longer, it's going to be a smaller percentage which will influence the calculation below. Also, it's the maximum, assuming that carbo-loading was done to max capacity, which may or may not be the case. To make it easy, I just assume 50% glycogen storage for a road marathon. This leaves me with a 50% deficit, i.e. about 1100 kcal. I know that I can take a gel with 23g carbs (=92 kcal) every 40 min plus a small cup (probably just 50-100 ml) of an isotonic drink which may have a few more kcal so I calculate with 100 kcal per fuelling station. Throw in the odd jelly baby/ slice of orange/whatever is on offer in between, I get still a few more kcal, roughly 120-130 for the 40 min. If I stretch that to an hour, I end up with 150-60 kcal uptake per hour. In a marathon of just over 3:30 h, I can take on board 3.5x160=560. My stomach is happy with that, it tolerates almost any kind of gel and small amounts of solids but I cannot go much beyond that, otherwise I start feeling sick (tried gels at 30 min intervals, nope!) To simplify again, I calculate with 550, which is half of the 1100 that I need. So 25% of the deficit comes from carbs taken during the race. the other 25% have to come from fat storage, so that also means that I have to burn about 150-160 kcal in fat per hour in a marathon to make it work. To sum it up: my hourly calorie need is about 600-640 kcal, divided up in 50/25/25 chunks for each fuel type/origin. Now the HR bit: From running parkruns without breakfast, i.e. fasted and after about 20-25 min of steady running before, I know that the ceiling is about 175 bpm, I cannot run at a higher HR than 175 without supplying any carbs (when fully fit, in a fuelled 5k race, I get HR up to 175 within the first km and it can easily hit 183-185 towards the end, but that's not possible here). That session results in about 50 min of fasted running. It's very uncomfortable running but it gives me an insight where the limit is for minimal fat burning. This is why I avoid hitting that ceiling in a marathon, even if it means that I'm being overtaken at every small incline in the first hour. I start running at 10-15 bpm lower than 175 and keep to that for the first 5-6 miles. Then I let it gradually ride up during the race until the final hour when I know that I can now make it to the finish at that HR. This strategy guarantees me negative splits, improving my position massively from about halfway and I'm feeling relatively comfortable until about mile 18-19 when I start hitting the ceiling. The last hour is quite uncomfortable but I know that I can make it to the end riding the 175, remembering the fasted parkruns. Thanks for reading that far. That's all I know about marathon fuelling. I'll get the generic formula that every runner can use for their own weight and post it here. The HR bit is something that everyone has to find out by themselves, I have no real guidance on it. I just know that this limit of minimal fat burning is very close to my threshold. No idea if that is the case for every runner or if I'm better adapted to fat burning due to the fasted runs that I do. It could be 5-10 bpm lower than threshold for others or even more. I hope that this post was useful and informative. If you have any further questions I can try and answer them. |
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Nov 2016
4:09pm, 9 Nov 2016
215 posts
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dibbers
tipsku Thanks for taking the time to write that. I read it all! But, I need to re read it once or twice to take it all in. I will be really interested in using the formula you're digging out. |
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