For those who've followed from my very early posts, you'll know that my aim is to run far, rather than fast. I've had too many highly problematic injuries to think about winning any trophies. I just want to run as far as I can. A big part of that for me is becoming better fat adapted. That means to say that even when running (albeit slowly), the vast majority of my calories should be coming from fat. That easy Zone 2 pace that you can theoretically hold all day and all night without crashing or bonking too hard... and without puking the 20 energy gels I've needed to take, because I was hammering through my muscle glycogen stores that empty faster than I can fill them.
For what I'm doing I need to run at a pace where my body is using the majority of energy from fat stores on my body, rather than try to keep up with endless eating that only gets way harder the more tired you get and the further you go. My enduring strategy for this has been:
to do the VAST majority of my training in Zone 2,
cut back on starchy and simple carbs in my diet,
and train frequently while fasted.
It takes time for the adaptations to take hold, but I now feel that I am much better fat adapted. The last few weeks have shown that with my run paces at Zone 2 increasing but my heart rate staying the same (avg 134 bpm) Three weeks ago I tested my Lactate Threshold and my FatMax (maximum use of fat for fuel) at the Human Performance Centre at the University of Bedford. It was tricky as I'm still having to nurse an injury in my Achilles/Ankle/Heel. This meant I had to take it easy and stop as soon as my LT2 (Lactate Threshold 2 or Lactate Turnpoint was reached) so as to limit the pain and any further damage. The test sees you run on a (very fucking comfy) treadmill, while wearing a breathing apparatus (which makes me look like some space-age elephant).
All the while, they took blood after each 4 minute run segment, before raising the speed of the treadmill (for your blood lactate levels. The test was pretty simple and the results were mixed, but expected. Lactate Threshold: The distance between my LT1 and LT2 zones was pretty short: My LT1 was coming in around 144bpm Heart Rate, and my LT2 at around 158 BPM. In simple terms my Lactate Threshold (as used by various Zones calculators) is 158. That's the point where my anaerobic threshold is crossed and I produce lactate faster than my body can feasibly use or clear it. This is where I go into rapid bonk territory if I hold that heart rate for more than an hour.
This is 10K optimum pace and half marathon fuck-yourself-up territory. I intend to do neither as I've done almost zero training in this zone. This means my Lactate Threshold is predictably shitty. I'm OK with that (for now), but will push the pace more as I put more of the injury stuff behind me.
Strides, fartleks and 1km fast repeats are the joys that await me in my summer training phase after I get the 100km out of the way. These will build the pace I need to run trail sub 8 minute kilometres that I can sustain in my Zone 2 (134 bpm) for 25km, up and down hills when I hit the Hebrides in September. Given I can comfortably currently run under 9 minute KMs at my forever Zone 2 pace on Trail, I'm definitely where I need to be right now... For now, 100km endurance, strength and injury rehab are king.... I'm slow as shit at the moment, but really don't care as i can run far... and that is what matters most in what I'm attempting. FatMax: For me right now this is the most important metric to understand. How efficient am I at burning fat for fuel rather than carbohydrate?
Some facts for you... An average man can store approx 800-1000g of glycogen. If you are using 100g per hour of CHO (carbohydrate) then you have enough for 10 hours. Then you are done. Once it's gone, it's gone.
But you can eat as you go, right? Well, this problem is exacerbated by the fact that you can only process the intake of a maximum between 40-60g of carbohydrate (which converts to glycogen) per hour. Taking 60g of carbs an hour (less than 2 energy gels) will only delay glycogen depletion over very long time frames. Basically you can't eat enough. In a 24hr+ race this can become a BIG problem if you go at a pace that prioritise CHO rather than Fat for fuel.
In a multi stage ultra this problem looks to be compounded as fully replenishing glycogen reserves takes at least 24hrs. So if you are at half stores after day 1, then you may well be at 1/4 stores of day 2, running on empty at day 3, and by day 4 you could be in a shitstorm of empty energy levels. This means there are few options when going really big distances such as a 100km or multiple stage back to back ultras, being:
Eat constantly and hope for the best. The problem here is that after a few hours your stomach lacks digestion ability due to blood being shifted to work on your muscle use. You end up feeling sick if you are burning through the tank of glycogen faster than you can fill it if your pace is too high (your Zone 3 or higher)
Run slower/walk more. This reduces the ratio of carbs to fats you are burning and allows you to be able to replenish more easily as you go
Train to be better fat adapted. This teaches your body to prioritise more fat for fuel, makes your physiological changes more energy efficient, and also allows you to raise the speed of which you run at in your zone 2
I chose option #3.
The question is, is it working?... Well, according to my FatMax test it is:
I can run a comfortable 7 KMH and burn only 33g/hr of CHO (Carbohydrate), where still 2/3 of my calories (63g/hr) come from bodyfat stores. It's only when I pick up the pace a little that the dial switches.
If I can spend the next few months further training to lift my walking pace (6kmh) energy balance (5g carb vs 52g fat per hour) to around 8 KMH speed, then I will be in fantastic shape energy-wise for even the longest of distances. At the moment I can walk forever without crashing in my energy. The aim is to run easy forever to do what I need to do in September.
This requires time, patience and more fasted running, fasting days, clean eating and pushing the pace up to slow down when my HR crosses around 138 bpm (top of my Zone 2 is around 140 bpm according to Zone formulas now I have my Lactate Thresholds).
The last 3 weeks since this test I've already raised the bar as I can now run comfortably in my Zone 2 (aerobic fat-for-fuel zone) at 7Kmh for 45 mins non stop before my heart rate starts to drift up. My energy feels great after this as well (but have to still go easy while managing injury).
What's encouraging is my TrainingPeaks fitness progress is still looking good. It's getting harder week by week to raise my Training Stress per workout as I'm becoming fitter. This means the hours I need to train are increasing bit by bit (8 hours this week and it's an easy week!!), but it's working and consistency is king!
The smoother rising line (that looks like a hill) id the line that matters most as this is my fitness increase over the last 3 months. 90 days ago, my fitness was at around 10 (after starting at zero when i started using TrainingPeaks). Now it is at 49.
I can see it in my latest MAF test which had me running 30 mins at 134 bpm average heart rate and covering 5.5km. It's a best ever score on my MAF test, so things are obviously shifting.
There's a way to go before I can hold anything like that kind of pace for 3 hours straight (which is what I'll need to make the mid-point ferry cut-off on day 1 of my Hebrides 300k challenge)…. but it's a big step forward, and that is making me feel good right now.
Another win this week has seen my weight start to move down once more. As of Christmas I was at 108Kg, and as of today I am at 100kg. Shifting weight has been very hard for me. Even with the amount of work, fasting, clean eating, etc I have put in the last couple of years. Finally it looks like adaptations are starting to happen. While weight loss is not linear (it tends to come off in fits and starts), I should be well on track towards the 90kg target for the summer. This is a BIG help and will take some of the pressure off my injuries in reaching that target. Overall, things are actually looking quite good right now. I'll enjoy it for now and also avoid ANY complacency as I know how quickly things can change and reverse if I screw something up. Thanks for reading....
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