Carbs vs Protein For Endurance – Which Is Better?

Carbs vs Protein For Endurance – Which Is Better?

Completing a half marathon has been on
your bucket list for ages. You finally round up a bunch of friends
and sign up for a charity run in six months after one of your training
sessions a friend suggests that you should add protein to your diet to
perform better on your run but another friend tells you that loading up on
carbs is better for endurance so who’s right if you’re into endurance training
like cycling or long-distance running should you focus on carbs or protein first let’s have a look at what happens
inside a muscle during exercise all dynamic forms of exercise like running
require contraction of your muscle to generate force and then relaxation so
that the cycle can repeat itself deep down inside a muscle there are two long
fibers called actin and myosin for a muscle to contract and generate force
myosin needs to grab the actin fiber and pull it of course all of this doesn’t
happen on its own muscles need energy to make the magic happen when myosin pulls
an actin fiber the main fuel being burned is called adenosine triphosphate
also known as ATP think of a muscle like the engine of a petrol thirsty car each
muscle contains a small store of ATP which is only enough to last for about
three seconds of muscle contraction so muscles need a way to continuously
refuel and make new ATP well the body has three energy storage tanks that it
draws upon to power this ATP guzzling machine
first is creatine phosphate muscles break down creatine to rapidly make new
ATP but creatine can only generate enough ATP to power a muscle for about
10 seconds so creatine is good for short bursts of muscle power like when lifting
weights but not so good for endurance then there’s a second tank the glycogen
lactic acid system glycogen is a stored form of carbohydrates when you eat a
slice of bread the carbs that your body doesn’t use immediately is stored in the
form of glycogen all body cells can store glycogen to some extent but your
liver and muscle cells can store especially large amounts when muscle
sense that the ATP and creatine stores are running low muscles start breaking
down glycogen into glucose when there isn’t a
lot of oxygen available this glucose is converted into lactic acid which leads
to the production of ATP the glycogen lactic acid system can power muscles for
about one and a half minutes which is much better than the ten seconds of the
creatine system but not enough to get you through a half marathon also lactic
acid causes extreme muscle fatigue the final trick of the body sleeve is the
aerobic system here glycogen is broken down into glucose then to pyruvic acid
but rather than being converted into lactic acid pyruvic acid is instead sent
to a powerful place in the cell called the mitochondria in the mitochondria
pyruvic acid reacts with oxygen to produce enormous amounts of ATP
so to recap stored ATP and creatine can power a muscle for about 10 seconds the
glycogen lactic acid system powers the body for about one and a half minutes
but what about the aerobic system well it is essentially unlimited as long as
there are enough nutrients the aerobic system will continue to pump out ATP but
what happens when the body runs low on glycogen well fat stores can be broken
down to make significant amounts of ATP and it can also convert protein into
glucose but this process is not very efficient so in order of priority the
body likes to use glycogen first then fats and protein only as a last resort
so now that we know that the body likes to use carbs and fats for energy let’s see
which type of diet performs best for endurance training a high carbohydrate
diet a high fat diet or a mixed diet on the left is a percentage of energy
coming from carbs with zero percent on the bottom and 100% on the top on the
right is the percentage of energy sourced from fats with zero percent on
the top and a hundred percent on the bottom for an athlete on a mixed diet
initially all the energy comes from carbs but they used up fairly quickly at
four minutes of activity about 75% of energy is from carbs and 25 percent is
from fats at two hours the athlete reaches exhaustion at that point fats
providing most of the energy with only 35% coming from carbs what about a
high-fat diet even at the start of the event only 80% of the energy is from
carbs with fats providing the remaining 20% mainly due to low glycogen stores
the athlete reaches exhaustion at about 1 and a half hours into the event but the
story is very different for a high carb diet the glycogen stores are so abundant
that even at one hour into the event around three-quarters of energy is from
carbs and the remaining 25% from fats the athlete reaches exhaustion at the
four hour mark which is about two hours longer than a mixed diet when recovering
after an event an athlete on a fat and protein diet takes a long time to
recover their muscle glycogen stores but an athlete on a high carb diet can
rapidly regain the muscle glycogen stores of the first 40 hours of recovery
so high carb diets easily outperform a mixed or high-fat diet but is there
still a role for protein in one study cyclists were put on a high-protein
moderate carbohydrate diet for seven days and then completed a Time Trial
they were then put on a high carb moderate protein diet for seven days and
completed another Time Trial the sequence of the two diets was randomized
the results showed that cyclists on a high-protein diet
took about 20% longer to complete the time trial compared to the cyclists on
the high carb diet but some studies do show that adding protein can reduce
blood markers of muscle damage and improve feelings of muscle soreness
after a grueling event so it is thought that adding protein to a high carb diet
can assist with the recovery and help offset muscle damage there are three
take-home points if you’re training for an endurance events like a half marathon
you should focus on a high carb diet one study recommends getting six to ten
grams of carbs per kilo of body weight per day second
muscles need about 48 hours to build up the glycogen stores even on a high carb
diet which means that you shouldn’t do any high-intensity exercise for two days
before a big event and finally protein supplementation may
assist with recovery one study recommends an intake of 0.25 grams of
protein per kilo of body weight per hour of endurance exercise thanks for
watching and I’ll see you in the next one

About the author


  1. Personally, I find my cardio and running sessions easier when I've got proportionally more carbs in my diet. What do you think of a high carb diet for endurance? Do you think carbs help or do you think they make no difference to your performance? Let's talk about it in the comments!

  2. I don't trust your source for the diet-exhaustion graphic, there's too many variables. Was it with fat-adapted individuals? Was it a misleading high-fat diet that still had significant carbs? Personally I find that I hit exhaustion much faster when I'm fueled by carbs, vs better endurance when in ketosis.

  3. Would this also be the reason to eat lower or less carb if you were trying to lessen body fat percentage through endurance exercises? Since your body will burn more fat than carbs while exercising.

  4. high protein consumption is vital for resistance training, it significantly reduces the recovery time after each session

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