As I have mentioned previously one of the reasons I got
interested in the LCHF diet is the possibility that it could be beneficial to
distance running; this is what gets me interested as I am getting older and the
possibility that I could carry on for a few more years at a decent level is
exciting.
So I ran my first LCHF marathon back in March and it was all
easy enough. I like the food and as you may have read previously I was able to
train just as long and as hard as I have done before. The London Marathon and the South
Downs Way Relay were to follow and I was hoping to take a close look at
fuelling and energy levels when running for more than a couple of hours. But
then I picked up a minor injury and have had a couple more since then ( I
should add that these were related to skiing and mountain biking, not running).
As a result I have not really been able to study this subject in great depth
yet.
But it is an interesting subject nonetheless and so here is
post number 1 on this subject.
How long can we keep going for?
Mention the word Marathon to a novice runner and a few ideas
will come to mind; such as ‘why?’, or ‘26.2 miles!’, or ‘Hitting the wall’. The
last of these is the one that strikes fear into the hearts of most runners.
Hitting the wall is simply another description for running
out of fuel. Most of us only have the capacity to store enough glycogen to run
for about 2 hours. This is why we generally carb-load before a marathon,
to fill the glycogen tank up to the top. Refuelling in good time ensures that
we don’t hit the wall and so long as we have done the training we should
complete our big run. We learned this back in the eighties and Lucozade and
Gatorade have made a heck of a lot of money ever since.
Clearly finishing a marathon depends on refuelling, or to put it another
way, on consuming sugar.
So how did marathon runners manage to train for and run
marathons (often very quickly) before the advent of Gatorade? Simple,
their bodies had adapted to burn fat as well as glycogen. They trained hard and
in the absence of carb-gels and carb-drinks their bodies became rather good at
switching from carb-burning to fat-burning when the need arose. Most
mere-mortals do not train this hard, and if we are on a traditional (and NHS
recommended) high-carb diet, we will need to
take on fuel on our long training runs and we will rely on fresh fuel (carbs)
on Marathon day.
LCHF runners train our bodies to burn mostly fat, with
a small proportion of carbs. So, given suitable training we ought to be able to
keep running for longer; much longer, without the need to refuel in the same
way.
So how far can we go? And how fast can we go?
As you can see Peter is pretty serious. He has determined that a suitably trained athlete
(himself) can keep going all day long so long as he doesn’t run out of carbs.
Clearly the smaller the percentage of carbs being burned the longer we should
be able to run for. A key point is that most of us can regard our fat stores as
effectively limitless for these purposes.
We all burn fat as well as glycogen. The point at which we
switch to burning more glycogen than fat has a profound effect upon how long we
can run for before hitting the wall; the earlier the switch the sooner we run
out. Dr Attia found that on a high-carb diet this switch occurred at a heart
rate of 104, or 33% of his maximum output (or VO2 Max). When in ketosis (on a
LCHF diet) the switch came at a heart rate of 162, this being 84% of his VO2
Max. Don’t forget that he is an elite athlete!
The diet brought about more than this simple change (note
that his maximum output had lowered), but even though his VO2 Max had decreased
by 12% with the change of diet he was now able to use his glycogen stores very
much more efficiently.
After tests both cycling and running Dr Attia has figured
that when he is working at his ‘all day’ rate he is working at about 60% of his
VO2 Max. On a high-carb diet this required
95% of energy to come from carbs. On a LCHF diet with his body in ketosis this
required just 22% of energy from carbs (or strictly from glycogen). So buy
lowering the requirement for carbs he is able to go for much longer
before running out.
Another aspect of high-carb fuelling is that when exercising
for more then 1-2 hours our livers simply can’t process enough carbs per hour
to keep the tank topped up. The normal limit is about 50 - 60 grams (or 200-250
calories) per jour. There are 4 calories per gram of carbs; hence the
need to take on carbs early in a run, and keep topping up the tank regularly.
If you leave your refuelling until you feel tired and you are running at
a rate that requires about 800-1000 calories per hour then it will quickly be
too late for consuming more carbs to be of any help. Here I must give credit to
Sarah Rowell. Not only is she the author if the great book “Off Road Running”,
where I first learned about trail and fell running and nutrition; but she was
also the record holder for the Beachy Head Marathon for 5 years after trouncing
all the men in 1986.
How many of us have wondered “what might have been” as we
tread that painful last 8 miles towards the finish line with no carbs left but
a reserve tank full of fat gagging to be burned? When we decide to run long on carbs, we
are all treading an unavoidable path towards that same wall.
Now consider what those last miles might feel like if we
were only consuming 25% of our calories (250 grams per hour) from glycogen. We
could keep the glycogen tank full as long as we like if we re-fuel
appropriately.
Is it any wonder that so many ultra distance runners are
using a LCHF diet?
My attempts to replicate this investigation have so far been
thwarted by a dumb show-off-dad injury and some bad luck. However I can attest
to the fact that running the Hassocks Sport Relief Charity Marathon on LCHF did
not leave me feeling even slightly drained or hungry. I ate eggs and bacon
before the run and just a couple of cups of soup during the run. But I was not
going particularly quickly (I averaged about 6.2 mph on a heart rate of about
130) - nowhere near 60% of my VO2 max.
So I thought I’d call upon the experience of Marina
Bullivant. Marina is becoming a bit of a legend around here, having run all 5
Brighton Marathons. After the 4th run she switched to a LCHF diet, lost a stone
and a half and then proceeded to beat her PB from 3 years earlier. She has run
3 Marathons so far this year on LCHF, each
harder than the last. I asked Marina a few questions about the way she eats and
runs:
Q: How long have you been on the LCHF diet?
A: Since June 2013.
Q: Can you estimate how many grams of carbs you eat per day
on average?
A: Malcolm, I haven't ever calculated what this might be, or
even thought about it!
Q: When you run for over an hour do you use any kind of food
for fuel? –
A: I only really fuel for races, and then only half marathon
and above. SDW Relay - sausages, breakfast muffins (eggs, cheese, veg,
bacon), cheese, nuts - deviation is Janna's homemade barrabrith (fruit teabread
with loads of butter!). Brighton Marathon I took a couple of the gels
they were handing out and wished I hadn't - got stomach pain - stupid thing to
do as I never take them normally! And still got cramp in my calves!
I now take salt/electrolyte capsules with water on runs over 1.5
hours, no calf cramps so far!
Q: What is your average mileage per week? Has this
increased on the Diet?
A: I'd have to have a look at my records - it has probably
increased since June 2013, as have been running longer races, so training further.
but, as you will see in answer to question below - definitely faster.
A detailed conversation revealed that the average has risen
from about 40 to about 50 miles per week.
Q: What is the longest that you have run for using
this regime? –
A: Three Forts Marathon - 27+ miles (May 2014 - my longest
ever run).
Q: After a long run how long does it take to recover before
you would run again?
A: 24 hours!
Q: Is this recovery rate a change from your recovery rate
prior to the diet?
A: And thinking about it, this was probably not the case
before, would say that previously 2-3 days.
Q: What are your 5K and marathon PBs? (here I am looking at
the difference between the two paces – what is achievable on LCHF).
A: 5K 22.32 (June 2014). Marathon 3:46:36 (April
2014).
I particularly liked Marina’s answer to the second question
- she is not counting carbs at all. Not very scientific though, so I quizzed
here a bit further and I reckon that she eats about 60 grams of carbs per
day, apart from a bit of a blow-out with a roast potato or two with dinner on
Sundays which puts her up to about 120 for that one day.
Assuming that Marina is running at close to her VO2 max for
a 5K at 8.4 mph, and she runs a marathon at 6.9 mph then her marathon pace is
82% of her VO2 Max.
There is a big difference between Marina and Peter’s all-day
rate VO2 Max 80% and 60%. This is likely to be because Peter is an elite
athlete with a very high VO2 Max in the first place, whereas Marina just trains for and runs long distances. I think I
should have mentioned that this is not rocket science but we can see that
Marina is achieving something rather special here; she has lost weight and she
is getting more efficient at distance running. Her recovery rate in particular
is amazing; she trains the day after running a marathon. Now I never managed to
do that!
There is a suggestion that LCHF leads to less inflammation
in the body. This is critical in the case of atherosclerosis (inflammation of
the arteries) as it means that we are less likely to develop heart disease on a
low carb diet than on a high carbs one. You may recognise this as the subject
of my earlier posts (
http://lchf4runners.blogspot.co.uk/2014_04_27_archive.html
). But this also has a bearing on the inflammation on our bodies caused during
training; if there is less soreness from training then we should recover
quicker and can train more. This is what Marina seems to be finding.
This experience is mirrored with another correspondent
Simon, a GP on the LCHF diet, who states that
“Since going low-carb I seem to get less muscular aches
in my legs the day after a run; but possibly this is just due to the passage of
time rather than my diet.”
Simon has seen improvements across the board, not just for
endurance running:
“I had thought that my fastest times were behind me. I
started reducing carbs 18 months ago and within a matter of 2-3 months was
running faster. I have lived the LCHF lifestyle for over a year now and have
never run as fast.
Last month I set a lifetime best over 5K and have
improved my time over 10K by nearly 2 minutes. My passion is fell running and
have seen my times tumble compared with races a year or two before and not by
small amounts - 11 mins off a 14 miler in Pendle and 32 mins off the Three
Peaks Mountain Marathon. These are races I have done several times before so I
have a good idea of what I am capable of running.”
This all suggests that LCHF may indeed assist recovery
and perhaps even improve performance. My own memories of the Three Peaks Fell
Race centre largely around climbing
Ingleborough
splattered with sticky pink energy drink.
I was also hoping to write about the South Downs Way
Relay on LCHF. This 6-person team event covers the 98 miles of the SDW in somewhere
between 11 and 14 hours with each team member running 3 legs at close to threshold
speed.
(The Arena 80
Vets team from 2008)
This race presents particular challenges with regard to
fuel – you have to get plenty of fuel down in order to keep going all day, but not so much that you might get a
stich from running too soon after eating. Many runners find it hard to get food
down at all after a hard run and that compounds the problem.
I have run the event three times for my club Arena 80 and
we have come third, second and first in the fiercely contested vets category. On
each occasion I have gulped down a pasta, tuna and veg salad the moment I
finished each of the first two legs and drunk energy fuel liberally. Luckily I
can eat just about anything anywhere (the cook ran out of popcorn and bacon
when I was climbing Kilimanjaro), but I still felt worried about energy all day
long. Other runners were clearly having bigger problems and the changeover
stations were strewn with messy corpses and discarded energy gel packets.
I missed out on the relay due to injury this year, but
Marina was invited to join a ladies team from Hurstpierpoint. And so she was
able to road-test the LCHF diet. In short it was a doddle. While several of her
team-mates suffered from stomach cramps and lack of energy Marina ate some
egg&cheese muffins, cheese, nuts and some fruit tea-bread
washed down with a good amount of water & salt tablets. That’s all. She
reports feeling satiated and strong all day long.
Now as I said earlier Marina is superbly adapted to
distance running, but as a first-timer in this gruelling event she did appear
to shine.
The key lesson here for LCHF runners is that if we want
to run all day long then we can do, but we still need to eat a few carbs to keep the tank full. Marina had some
bread. I might eat some flapjack or drink a malco-pop; but we do not need to
worry about hitting the wall if we are fuelled by fat.
Tim Olsen, the winner of the 2012 and 2013 Western States
100 is on LCHF
Sami Inkinen, a persistent winner of Ironman races is on
LCHF. He also writes about his performance here
http://www.fatchancerow.org/. He
is currently rowing from San Fransisco to Hawaii to raise awareness of the
dangers of sugar.
