Science Interviews


Tue, 31st Jul 2012

A Naked Scientist is Put Through Her Paces

Chris Easton, Kingston University

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Kingston Universityís exercise physiologist Chris Easton puts Naked Scientist Meera Senthilingam through her paces......

Meera - Various physiological traits are monitored and improved upon at the elite level.  But Chris also took me on a visit to his lab.  A lab filled with bikes and treadmills, all with many forms of machinery attached to see some testing in action.  Unfortunately, not on Usain Bolt but instead, on myself...

Chris -   We do most of our performance testing in here for University action consultancy work and for teaching as well, and obviously for runners, weíd use the treadmills for those performance tests.

Meera -   So, this particular treadmill, it doesnít look like the average one at the gym.  So, itís got much bigger screen, a variety of settings and two computer screens next to it.

Chris -   Yeah, thatís right.  So, this is a treadmill that we can use for incremental exercise tests.  We can very quickly change the speed and the gradients, and what we have alongside is a metabolic analyser, a device that will allow us to measure your expired air to see how much oxygen you're using and your energy expenditure during exercise.

Meera -   Initially, it looks like just a box with a variety of wires coming out.  How would you actually measure that on someone?

Chris -   What we do is we will attach a face mask to you and weíll actually attach you to the system as it were.  So, the wires will be connected to your face mask, weíll measure the concentration of oxygen and carbon dioxide, your expired air, and also your breathing rates as well, so how much air you're actually breathing out with each breath.

Meera -   How fast does this treadmill actually go?  And is that representative of how fast an endurance runner would run?

Chris -   This treadmill only goes up to 20 kilometres an hour and our other treadmill goes up to 40 kilometres an hour.  But to give you an example, this one wouldnít even be able to go up to the speed of the world record marathon pace, which is run close to 21 kilometres per hour.  I think if we took even most fairly fit individuals off the street, they'd be lucky to maintain that pace for more than a few seconds.

VO2 max measurement through a modern metabolic cart during a graded exercise test on a treadmillMeera -   Chris, I've got my trainers on.  I'm going to have an initial go anyway.  So what other kinds of things you would expose someone to?  So I'm just getting on now.

Chris -   So what we do is we do an incremental exercise test.  Weíd start you off at fairly low 8 kilometres an hour or so, and then weíll increase either the speed or the gradient to the point where you can't keep up with the speed of the treadmill.

Meera -   Okay, so weíre not getting to that.  You're going to put it on the initial 8 kilometres an hour.

Chris -   Thatís right.  Weíll just do the very initial stages of the test, collect some of your measurements and we can see how they are.  Just to warn you that the speed does start fairly suddenly so be prepared for the treadmill to start.

Meera -   Okay, you're right.  So, I've got a heart rate monitor on at the moment already but as well as this, you want to look at what's going in and out of my breath.

Chris -   Thatís right so weíll measure how much oxygen you're using, how much carbon dioxide you're producing, as well as your breath, your ventilation rate as well.

Meera -   Itís actually quite fast paced walk.

Chris -   Yes, Iíd probably see it as a light jog as opposed to a walk.  There you go, maybe more comfortable too.

Meera -   Actually, thatís better.  Okay, so I have the face mask on now.  Itís very tight.  In fact, when I breathe out no air is leaking out.

Chris -   Yes, thatís great.  So it means weíve got complete seal.  So, all the air that you're breathing out will be assessed by the analyser.

Meera -   Just 3 to 5 minutes on the treadmill was enough time for Chris to get a range of information about my bodyís response to exercise and the general state of my fitness which although nowhere near of that of an elite athleteÖ

Chris -   ...Slow the speed of the treadmill down and Iíll bring you down back to a walk...

Meera -   ...Wasnít too laughable.  Okay, so the face mask is off but now, you need a blood sample.

Chris -   Thatís right.  So what weíll do is weíll collect a very, very small sample of capillary blood and weíll assess that for lactic concentration.

Meera -   So, my fingers you need?

Chris -   Thatís right.

Meera -   You're squeezing my blood out of my finger now.

Chris -   Yes, okay so I'm just using a portable analyser to collect that very small sample of blood andÖ

Meera -   So this is essentially like a little box, the size of maybe two matchboxes together with a small strip sticking out which is what you put my blood onto.

Chris -   Thatís right, yes.  So, really good because it allows us to do a lot of these measurements in the field.  So, at side of the track, at the swimming pool, and in athleteís natural environment as opposed to having to ask them to come into the lab and do these things on the treadmill.

Meera -   So while still waiting for the results of my blood test, youíve got a variety of statistics about my performance just at this basic level already there.  So, is this I'm assuming from my face mask and so on?

Chris -   Thatís right.  So we took some very basic measurements and looking firstly how much oxygen you're using every minute, and thatís telling that you're using 2.2 litres of oxygen for every minute of exercise and to put that in a slightly different way, you were using 32 milligrams of oxygen for every kilogram of your body mass.  So thatís nice because it allows us to compare between people of different body sizes.

Meera -   And how would that compare say, to an athlete?

Chris -   An elite athlete, you'd expect their oxygen consumption would actually lower because they're more efficient so they would require less oxygen, less energy, to produce the same running speed.

Meera -   So, how much lower would this be?

Chris -   I mean, itís difficult to say for sure depending on the athletes, but you might expect theirs to be somewhere maybe at 20 milligrams per kilogram per hour or so.

Meera -   And you have some other figures noted down there.  What are these?  So something is 0.74.

Chris -   Yes, so thatís a measurement called the respiratory exchange ratio, respiratory quotient.  And very simply, itís just a ratio of the amount of carbon dioxide that you're producing to the amount of oxygen that you're using.  Now thatís very, very useful because first, they can give us an indicator of your metabolic rate, if we take the measurement during rest.  But also, it lets us know the type of fuel that you're actually using for that exercise.  So your respiratory exchange ratio was 0.74 which indicates you're predominantly using fat for that 8 kilometres an hour which is obviouslyÖ

Meera -   Itís a good thing?

Chris -   Yes and thatís what you'd expect.  As the intensity is low, you use more fats.  As you progressively increase the intensity, you use more carbohydrate and consequently, you increase this respiratory exchange ratio.

Meera -   And so, I think my blood tests now are ready.

Chris -   Yes, so measured the lactic concentration in your blood and it gave us a value of 1.8 millimoles per litre, so thatís 1.8 millimoles of lactate per litre of blood and thatís very, very slightly raised from resting values.  But certainly indicates that the intensity of exercise that you did there was below your lactic threshold.  So we havenít seen that large rise in lactate that we'd expect to occur after lactate threshold.

Meera -   And so, if somebody now walks in through the door thatís a good athlete.  What do you need to do all in all to get them to hopefully be an elite athlete?

Chris -   The question is almost impossible to answer.  I mean, itís only such a small percentage ever actually make it to that elite level.  As physiologists, we can contribute to that in some way by measuring some of these parameters during exercise, but ultimately, there are so many other factors from psychology and genetics that will contribute to whether somebody truly does make an elite athlete.  If there was one training programme that could made everyone great then you'd have millions of elite athletes then and of course, thatís not the reality.

Meera -   Unfortunately, although I was reasonably fit, Chris didnít see much hope of me being a GB representative at Rio 2016.  That was Chris Easton from Kingston University.


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