- Hello and welcome to a very special edition of
GCN's How To... with Professor Asker Jeukendrup,
who has very kindly agreed to give us
some of more of his time after we did that ask with him.
And we got loads of questions from people on how to really
personalise their nutrition for their particular problems.
Professor Jeukendrup, thank you very much for having us
in your beautiful office again.
- Thank you for having me.
- I've mentioned before your numerous achievements, but
you've worked in the field of sports nutrition and
performance nutrition and exercise science for many years.
And I know that you've worked with some very high level
sports teams in football, cycling.
You've worked with Chrissie Wellington,
Haile Gebrselassie, tell us a little about your role in
with high level athletes, advising them
in nutrition I think.
- I think it's a relationship that works both ways.
So I listen carefully to what elite athletes tell me
and then they tell me what their problems are.
And those are things that we've taken to the lab,
to try and find the answers.
And then hopefully, I can then help them with these answers.
And that's how I've worked for many years and
indeed I had the opportunity to work with a number of
great athletes and I have to say that I have learned a lot.
I hope that they learned a bit as well.
- Yep and I think they have,
but you should know that Asker's also himself
a very keen triathlete, cyclist, runner,
so he knows about the user end of sports nutrition as well.
So anyway, let's get down to business.
We had quite a few questions from people who
wanted to know about nutrigenomics and whether
they should go out and get DNA testing to find out precisely
what they should be eating in their event.
So we thought we'd come and ask you about that.
- [Asker] Yeah, alright.
- [Interviewer] So, can you tell us about
what you think about that to start with?
- Yeah, I think first of all, I think personalization
is the future in this field.
For me there's no question about this.
Every individual is different and we need to address that.
Nutrigenomics has been suggested as a solution for this,
for this problem where you measure
genes and then out of that roles some advice.
And I think some of that comes from the medical world,
where we see a lot of this where based on your genetic
makeup you may or may, yeah you may be prone
to certain disesases or you may respond
to certain medication.
That work in the medical field is all based on
a very large number of studies.
And also the studies themselves are very large,
sometimes 10,000's of people that were followed in time,
some people that get the disease,
some people that don't get the disease and
based on that you can see then that certain genes
send people in different directions.
- But it's a statistical correlation.
- It's very much based on statistics so it's probabilities.
- Yeah.
- And now in nutrtion we see similar,
now this is not sports nutrition now, but just in
general nutrition we see something similar.
We have fewer studies there, but
still the studies are very large.
When we come to sports nutrition there's a little
different picture because there we have actually
very few studies and the studies that we have,
they don't have 10,000's of people, typically
their studies have six or eight or ten people at best.
And it is very very difficult to draw conclusions
from those small numbers of studies with small sample sizes
to do a really complex question.
- A similar problem to in sport science in general where
training protocols are tested on quite small groups
of people and it's very hard to generalise to elite level
or to people in general.
- Yes, that's correct.
- Yeah.
So at the moment you'd say that maybe a DNA test
is not the solution.
That it'll tell you bam, take this bar, this gel, and
that carbohydrate drink, its more --
- Yeah, I think there's several reasons why I think that
that it's not the solution yet.
First of all, because the field is, we have so few
studies to base this on and it's too early days.
But also, the real reasons why you need to eat somethin'
to perform are probably not so much dependent on genetics.
- Yeah.
- So for example, the exercise intensity and the duration,
the type of sport you do determine much more
what you need, then your genome.
- So the reason that I don't respond the same way
to bar x or gel y as my friend does is more to do with
how hard I'm riding or what I've trained myself
to eat as well.
Presumably that plays a part as well?
- Yeah.
Or even what your goal is.
- Yes.
- Right, if your goal is weight loss
or your goal is to perform tomorrow,
you're eating differently.
- Yeah, that's a good point, yeah.
So there is, one should try to personalise one's nutrition,
but maybe not based purely on DNA.
- Yeah, that's correct.
And maybe in the future it'll start to play a bigger role.
There are some examples where maybe this is useful already,
but it's very very early days.
- Yeah.
- Like an example is caffeine.
We know that some people are much more sensitive to caffeine
than some other people.
That is, you can trace that back to the genome.
- Oh really?
- You measure that.
So that's one of the few things
that we can already do today.
- Oh right, I thought that I was not very sensitive
to coffee because I drink too much of it.
But it's partly my genes, okay.
(Asker laughing)
It's good to know.
Given that there are all these different variables about
exercise intensity and goal and
well just personal preference,
can you tell me how we as cyclists should go about
planning our nutrition for either training or racing
or whether there's some interaction between those?
- Yeah.
- There's so much information out there,
feels like sometimes there's too much information
from many different sources and it's very easy
just to try and copy what other people are doing.
Where's the starting point, do you think?
- I think for me the starting point is always
understanding the sport itself.
- Yeah.
- What is it that determines the performance in that sport?
I think it's almost going back to basics.
- Yeah.
- Like what is it in this particular sport,
that determines performance.
In cycling for example, that's gonna be different,
of course, in mountain stages than it is in time trials.
And so it really depends, but you have to
go back to that basic.
Once you have a good understanding of that,
I think the question to ask is okay.
Now with your training, what are you trying to achieve?
What are your main goals?
So that for me is the next step.
And as I said earlier, if your goal is weight loss.
Your programme will look quite a bit different
than when it is purely to perform.
So goals is next
and then it is about what timing are we talking about.
Are we talking about the 24-hour
diet?
- [Interviewer] Oh, yeah.
- [Asker] Are we talking about what to eat before training?
Are we talking about what we eat during?
So that's the other component.
- So if we were to take say,
a cyclist who's fairly experienced
but they're taking on a big event this year,
for example like a long sportive, let's say five to seven
hours long, a major undertaking.
How would they go about knowing how to time their nutrition?
There are, I believe there are guidelines for
how much carbohydrates someone should take in.
if they're working above a certain level
for a certain amount of time.
Especially if there's a key goal, is what to keep
eating as much carbohydrate as you can really.
- Yeah, not necessarily.
- Okay.
- 'Cause that depends on what your goal is.
- Yeah.
- If what your goal is to perform at your maximum.
- Yeah.
- The advice will be slightly different than when
your goal is to reach the finish line.
- Yeah.
- And to complete the event.
And if your goal is to complete the event,
you probably don't need as much.
- Yup.
- So that's one factor, the other factor is
your absolute levels.
- Yeah.
- The power that your power output is really important.
So if someone produces 300 watts versus 150 watts on average
that's going to be a different demand.
- Yes, yep.
- That's important to understand and I see a lot of,
a lot of athletes who
maybe take longer,
who fuel the same that a professional rider would do
and that's not necessary.
- No, overdoing it on carbohydrate
is an extra on the body that it can't cope with
under high perform loads and if you're trying to digest
and put out power at the same time it's not always a great.
- Yeah, that is definitely a challenge.
- Great, thank you.
So, how would we go about knowing about how much
carbohydrate to take in, during an event?
- We do have some guidelines for that and
the amount you need to take in probably depends on
the duration of the exercise.
So if it's only an hour, two hours,
you need smaller amounts.
If you go over two hours you need probably,
say between 30 and 60 grammes of carbohydrate every hour.
- Yeah.
- If you take this really seriously,
your power output is high and you're goin' over
2.5 to three hours, this is where you may even think
to go higher than 60 grammes per hour.
- Okay.
- And up to 90 grammes per hour.
But, this is where it gets a little tricky because
your body can absorb, most peoples bodies can absorb,
up to about 60 grammes per hour
of any type of carbohydrate and so that's not,
that's no problem.
If you go higher than 60 grammes,
then that may be a problem in terms of the absorption
unless you take the right types of carbohydrate.
- Okay.
- So I would always advise, do not go
higher than 60 grammes per hour.
- Okay.
- Unless you know about this.
- Yeah.
- And you know which carbohydrates to select.
- Yup.
- The carbohydrates you need to select to go higher.
- Yeah.
- Are a combination of glucose and fructose.
- Yup.
- Or maybe maltodextrins and fructose.
- And those are the easiest to absorb.
- Yeah, so that combination, they and,
the technical side of that story is
those are two types of carbohydates
that use different transporters in the intestine.
And if you only use one transporter,
it just gets saturated
and this is why you cannot absorb
more than 60 grammes per hour.
If you use the two transporters,
then that means that you can absorb glucose and fructose
at the same time and we've shown that you can then
go up to even higher than 90 grammes per hour.
- So you've got like a two lane road instead of
of a one lane bottleneck.
- That's correct, yeah.
- Thank you.
What about, so we had questions from people saying
obviously that fat is much more energy dense per gramme.
So if you could, why not take on 60 grammes of fat per hour
and you've got way more energy.
It's not as simple as that though is it in terms of
absorption into the body.
- No, it's not.
Unforunately, well there's two issues
with fat during exercise.
One, is that the liver is very slow.
- Yeah.
- Whereas carbohydrate is absorbed really quickly
and is in your blood within minutes.
And with fat that's a different story.
And this may take hours.
So by the time the bulk of the fat actually gets absorbed
you may be done with your ride.
So it's not the ideal energy source.
- More energy for the party yeah.
- It's not a problem to take a little bit
of fat on during exercise, but it's not a good fuel.
- Okay, thank you.
And then I come to the question of
what kind of carbohydrates.
So you mentioned fructose, glucose, maltodextrin.
What about these energy bars that are slow release,
based on oats or I know that obviously there are
really different carbohydrate chain links and that
affects the absorption time.
Personally, I really like eating flapjacks and oat-based
products, I have a soft spot for those.
What do you think about those and in sort of
high intensity events?
- [Asker] Yeah, in high intensity events,
that wouldn't be my first choice.
- [Interviewer] Oh well, yeah.
- In training and lower intensity event it doesn't matter.
It's not about delivering the energy as fast as possible.
But in high intensity events and races,
this is where you want to deliver the energy
as quickly as possible.
You also, at the same time, you want your intestine
and your stomach to be as empty as possible.
Because you want that, the carbohydrate to go through
that as quickly as possible.
So you only get that unfortunately with the...
- With the sugars.
- With the faster sugars.
- And oats have too much fibre and protein
and a little bit fat so they slow the stomach too.
- And often the products that have them also,
they have a little bit more fat, little bit more protein,
they are all things that slow down the gastric emptying
and thus the delivery of the carbohydrate.
- And slowing down gastric emptying can also
lead to stomach cramping I think if you have
too much food just sitting in your stomach
when you're trying to basically pedal hard.
- Yes, that's right.
- I've experienced that for sure.
- Yep.
- It's pretty unpleasant.
- Great, thanks Asker.
So we've got this rule of thumb or general rule for
how much carbohydrate on average for an event
when you're working hard.
But, in cycling events there are obviously obstacles
in that there are mountains, descents, corners,
you know maybe there's a sprint coming up or
a place you have to be at the front or
portions of the course where you know you're gonna be
working very hard and then portions when you're not.
How do we adapt our nutrition to fit into
the practicalities of a cycling course?
And that maybe sometimes you just don't have
a hand free to eat anything?
- Well there's two things you can do of course.
You have to be very clever with where you eat.
So we can say that from a laboratory it's easy, right?
So you can say, oh every 15 minutes you need to
take on board something and that's usually
what we do in the lab.
But, if you're riding outside and there are mountains
and hills and corners it's,
it's very tricky sometimes.
It is important to think about this beforehand.
And in the work that I do with professional cyclists,
we do this, we sit down, we say okay, this is the plan.
This is what we need to consume in the race.
What are the best moments to do this?
And they can usually tell me where the best moments are
because they've ridden those races before.
And then we plan it out that way.
The other thing that is imporatnt is that
you do need to get to your target of carbohydrate.
But, we've also shown that it doesn't matter so much
whether it comes from a drink or a gel or a bar,
but that it's low in fat and fibre and protein.
So you can mix and match and usually it means that
in the early parts of races, for example,
when the intensity is a little bit lower
and you can still eat, use more solid food.
In the last couple of hours
of races, it's mostly gels because that
only takes like a few seconds to take so those are things
that you can play with.
So pick the right moment and pick the right products
at those moments.
- Yeah, that's certainly what I would find,
that I would study the race course beforehand
or nowadays maybe a sportive course and work out
where I'd have a hand free to eat anything.
So, not on the descent for me, but also
I wouldn't eat a massive bar on the bottom of a climb
where I was gonna go hard because it would
come straight back up again, which is not pretty.
- Yeah, but you see that people do make those mistakes.
Sometimes just the beginning of the climb is a time
when you can actually eat but then you're still chewing
when at the steep parts.
- Yeah, you don't wanna be chewing when someone attacks
and you've gotta go in them, it's very messy.
Great, thank you very much.
I know that you've developed a way, a tool for
athletes to plan their nutrition
during events and during training,
can you tell us a little bit about that?
About what it's called and how it works?
- We call that programme CORE, what CORE really is
is that you have a
sports nutrition scientist in your pocket.
You can personalise your own nutrition plan.
What you get is all signs based, but also,
at the same time based on you.
It is also very practical because it uses the products
that you want to use.
So you get a plan that is just bulletproof
and you can go into your event knowing that this will work.
- When I used CORE to plan my race nutrition,
I actually wrote the plan on a bit of tape
and stuck it on top tubes so that I knew,
not that it was very complicated, but it reminded me
that at times of 40 I should eat this and drink this.
Or have consumed that by then rather than on my go,
it was really helpful.
Thank you very much, this was really interesting.
I think that'll be really helpful for some of our viewers
who have questions about how to plan their race nutrition,
their training nutrition even.
So I hope that helps answer some of your questions.
If you would like to check out some of Asker's other
huge knowledge on sports nutrition
you can have a look at this video down here
where we put your questions to him.
And a lot of questions about personalised nutrition came up
which we saved for this video, but there's lots
of really interesting discussions down there
in that video.