Tag Archives: Exercise

The Ultra Cycle Diaries – The Finish Line

by Daniel Brayson, King’s College London, @DrDanBrayson

Having never attempted anything like the Transcontinental Race before, my expectation ahead of the race was to complete it before the cut-off time, which was set at 15 days and 2 hours. In the very early stages of the race, I rode quite conservatively knowing that to finish within this time was critical for my sense of achievement. However, I very quickly realised I was capable of much more. I arrived at the first checkpoint in around 60th position, which surprised me. I then arrived at all the remaining checkpoints in higher positions than the previous one and was placed somewhere in the 30’s for the final checkpoint on the Transfagarasan highway in Romania.

The last hurdle

Approximately 1000 kilometres from the finish line in Meteora, I was in a good position to make a late charge for a top 30 position and I set about the task gamely. I rode through the remaining portion of Romania and a short section through Bulgaria into Serbia. Feeling hardened from the first 75% of the race I felt my performance improving rather than declining and set about three substantial climbs in northern Serbia with a certain amount of gusto and swagger. Temperatures were fierce, up into the 40°Cs, but I felt I had acclimatised to these by now and in my mind I was conquering these hills with no problems, better than any I had attempted previously at the height of the midday sun. Having capacity for only 1750 ml of water and a broken smartphone, I found myself rationing water as I couldn’t know when the next opportunity to resupply would arrive. I made up for it when I had the opportunity and guzzled litres at service stations but as it turns out, the damage had been done. Later that evening, when the sun had disappeared below the horizon and temperatures had dropped to the point it was “cool,” I started to suffer. I felt hot and restricted in my clothes despite the cool evening breeze; I became irritated by my clothes to the extent that I removed my jersey and rode shirtless for a while. After a little while longer, my feet felt hot and irritated too, so I took them out of my cleats and rode on top of those. Then suddenly my legs went completely: I’d hit a wall, pedalling felt like I was sitting on a ledge mixing cement with my feet, and I was overcome with delirium. I stopped at a service station and slept in a secluded area covered in pinecones for the night. I was so out of it I hadn’t noticed the pinecones at first, and stirred from sleep a few hours later to find myself cursing them wildly. At this point, I intended to crack on, but as I stood up I felt a wave of nausea overcome me, so I figured I needed more rest.

TCR_Hotel

In the morning, I ‘soft pedalled’ (rode slowly) for about 100 kilometres, at which point I came face to face with a steep hill at 1pm. Again, the temperature was up in the 40°Cs. With no obvious signs of shade on the sides of the road I looked around, feeling dejected. I had been riding next to a river and noticed locals frolicking in their bathers. I found a small quiet area and immersed myself, fully clothed, in a shallow part of the river and remained there in state of semi-consciousness for almost 4 hours. When the mid-afternoon sun was less fearsome I rode another 40 kilometres to the nearest town and holed-up in hotel for the next 8 hours. At this point, I could not stomach any solid food, and realised I was suffering at the hands of the extreme temperatures and heat exhaustion.

Lessons from the Transcontinental Race

At the time, I felt that I had not ridden at the right times of day in order to avoid the heat, and this point comes through as in my video diary. Now, as I reflect, I know that I couldn’t have ridden at night since I can’t suppress the urge to sleep then (remember response inhibition?) The logistics of trying to reverse my body clock in preparation for a race whilst performing a demanding vocation would be insurmountable. My feeling now is that I should have been better prepared to ride in the heat. Principally, I should have addressed two issues. Firstly acclimation: I should have trained for the heat. I didn’t, because being British I am not often enough exposed to extreme heat to actually appreciate the effects it has on human physiology and performance – and to believe these temperatures actually exist! However, training for heat has been shown to potentially benefit overall performance, not just performance in the heat, so if there is any chance of high environmental temperatures it is worth undertaking heat training regardless. Secondly, I should have allowed a greater carrying capacity for water and fluids. This was perhaps the biggest flaw in my preparation. At times I should definitely have been carrying at least 3 litres, if not more! I paid the price for this and by the time I had recovered I had to re-align my expectations back to finishing before the cut-off. So with the intention of managing my workload carefully, I gingerly clambered aboard my bike and set off for the finish line.

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The finish line

After a calamitous final section in which I suffered a terminal failure of my rear tyre, I walked the final 7 kilometres, in suffocating heat, and arrived at the finish line in Kalabaka, Greece, in a foul and dispirited mood. I was robbed of the glory of rolling across the finish line, triumphant and fulfilled. Nevertheless, I had finished and I had finished 12 hours before the cut-off. On the lack of glory at the finish my final thought as I left Kalabaka to return to the UK was, ‘there’s always next time’.

The Ultra Cycle Diaries – Nutrition

By Daniel Brayson, King’s College London, @DrDanBrayson

In cycling very long distances as fast as possible, ultra-endurance cyclists use an extraordinary amount of energy. Replenishing these energy stores is critical for racers to maintain performance and stay competitive. To achieve this, riders do not simply settle for 3 square meals per day, or even 3 big meals a day, which would simply not be enough! Instead, we eat more frequently, and because we do not want to stop too often, this means eating whilst riding: “grazing on the go,” as it is affectionately referred to amongst cyclists. This involves eating an array of convenient snacks ranging from the healthy – bananas, oranges and kiwi fuits – to the energy packed goodness of carbohydrate and fibre rich wholegrain bars, nuts for fat replenishment, all the way through to the downright despicable: chocolate bars, Peperami and lots of jelly sweets. Did I mention ice cream? There was a bit of that too. The overriding consensus amongst riders is that a calorie is a calorie no matter where it comes from, and you take all you can get!

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Biting more than you can use

Although it is intuitive to think that you need to eat a lot more to compete in these races, there is a limit to how much energy a human can take on board. Take the example of carbohydrates. The limit to how much carbohydrate can enter the bloodstream is dictated by a clever transporter system between our gut and our circulation. The ‘problem’ with this system, from the point of view of an ultra-racer, is that it can only transfer approximately 60 grams of carbs per hour from the gut to the bloodstream, maybe up to 90 at a push. In an ultra event, racers are likely to use much more. On top of this, this transport relies on an adequate blood supply to the gut to deliver energy to the system and facilitate it’s function. However, when cycling most of our blood supply is directed to the muscles because they are using so much energy. This can make this transport system slower and less effective and may lead to “gastrointestinal distress” – tummy ache to you and me! This is a common problem for ultra-cyclists, but it is even more common in ultra-runners, probably because of there is more jumbling up and down in the tummy, which I think is the technical terminology…

Measuring the loss of energy stores

If the human body is in a state where it can’t take on as much energy as it uses, it is likely there will be a net loss of energy stores in the body; this has actually been shown in a couple of studies which examined ultra cyclists. However, the magnitude of this deficit is up for debate. One study showed that it could be as much as 8000 calories per day, whilst another derived that it was a more conservative 1500 calories. This discrepancy is likely due to the fact that these studies chose very different methods of measurement. To add to these studies I attempted to use yet another type of measurement to see if I could determine my ‘energy status’ during the Transcontinental Race. I opted for measuring circulating glucose (sugar) and lipids (fats) by pricking my finger and then using an everyday device that a diabetic might use to monitor their blood sugar. Simple.

Or perhaps not. I found that when I measured glucose, cholesterol and triglycerides, values were usually either the same as or higher than the resting values that I measured before the race, which goes against the hypothesis that I would be suffering from an energy deficit, and the data generated by previous studies. I can think of a number of mitigating circumstances. Firstly, I had devised a plan to take measurements pre- and post-meal. Yet, it quickly became obvious that I would rarely find myself in a pre- or post-meal state, because I ate so often. Timing of measurements was therefore erratic at best. Also, continually lancing my fingertips became a painful burden: my fingers were wounded and bruised for most of the time I was racing. Eventually, I decided it was too much of a hindrance, especially as my chances of finishing the race were already jeopardised by heat-induced illness. Heat also affected my appetite and ability to adequately digest: I was nearly re-acquainted with more than one meal towards the end of the race and spent the last two days eating nothing but ice-lollies.

In case you needed reminding, this was no walk in the park! Come back next week to find out if the ice-lollies got me over the line!


Make sure you follow the blog and subscribe to our Youtube Channel to keep up with the Ultra Cycle Diaries. Check back every Wednesday for a new blog and video!

The Ultra Cycle Diaries – Fatigue

By Daniel Brayson, King’s College London, @DrDanBrayson

Cycling 4000 kilometres as quickly as possible inevitably means that fatigue plays an important role, and those who manage and deal with it well are likely do best in endurance bike racing. Fatigue is the over-arching term to describe the inability of an individual subject to maintain a performance output over time; in the case of the Transcontinental Race, a very long time.

The reduction of the body’s energy stores is a key factor in the development of fatigue. Elite bike racing teams focus heavily on it to avoid what is affectionately known in cycling circles as ‘bonking’: feeling hypoglycaemic, with your legs turned to jelly, and mild dizziness. However, whilst fuelling is undoubtedly crucial, the Transcontinental Race provides the added challenge of being one long stage from start to finish: no daily finish lines, no support team and massage waiting at the end of every day. Therefore, developing a race strategy also includes deciding when and how much to rest and sleep, and route planning – both of which will impact on fatigue. Managing these components to optimise performance in the race is no mean feat especially when there are other factors to consider which are completely out of your control…

Fatigue graph

This plot of my power output over time shows an overall gradual decline in power during the race (red), which could be dure to a multitude of factors including the distance cycled and the increasing temperatures. ©Daniel Brayson

Response inhibition – the power of the mind

Due to the fiercely hot weather, a number of racers made the decision to cycle during the night and sleep during the day to avoid the hottest part of the day. This strategy didn’t work for me: I find it very difficult to inhibit my physiological urge to sleep at times that I would normally do so; this was no surprise, as I would famously fall asleep in nightclubs during my undergraduate years! Those who can resist these kinds of urges have what is known as a strong ‘response inhibition’: they are able to use the fortitude of their minds to ignore the desire of their bodies to sleep, and power through. They are likely to be successful endurance cyclists too, since they may also have a strong response inhibition to fatigue! The reason for this has been discovered recently: to a certain degree, fatigue is determined by the effort perceived by an individual rather than just the energy reserves available in their muscles (Marcora & Staiano, 2010). In fact, studies have shown that when a subject stops exercising because of exhaustion, there is still energy left in their muscles suggesting that it is the brain that is the limiting factor to performance!

Stress and physical performance

Remaining on the topic of the psychological components of fatigue, it is also now known that dealing with stressful situations can increase the effort perceived by an athlete and have a negative impact on endurance performance (Marcora et al., 2009). During the Transcontinental Race I encountered numerous stressful situations. For instance, I lost lots of my gear by just forgetting to re-pack it and leaving it in random places. I lost a pulse oximeter – a device to measure the oxygen saturation of my blood – before I got anywhere near a mountain, missing out on some nice data. My phone, on which I was heavily reliant for navigating and for performing an app-based psychological test called the Stroop test, broke because of the heat. I bought a new one and exchanged my sim card, only to realise 15 minutes down the road that I didn’t have it. I raced back to the shop – it wasn’t there. Retracing my steps, I could no longer determine if I was sweating through physical effort or panic! I finally found my brand new phone, just peeking out amongst the packaging in which it originally came: I had thrown it in the bin!!! Fatigue begets fatigue begets fatigue…


Make sure you follow the blog and subscribe to our Youtube Channel to keep up with the Ultra Cycle Diaries. Check back every Wednesday for a new blog and video!

References

Marcora SM & Staiano W. (2010). The limit to exercise tolerance in humans: mind over muscle? Eur J Appl Physiol 109, 763-770.

Marcora SM, Staiano W & Manning V. (2009). Mental fatigue impairs physical performance in humans. J Appl Physiol (1985) 106, 857-864.

The Ultra Cycle Diaries – Man vs Heat

By Daniel Brayson, King’s College London, @DrDanBrayson

A word of advice to budding ultra-cyclists: don’t climb steep hills in a heat wave! High temperatures came to define a large portion of my cycling race across Europe, especially the further eastwards I rode. On many days, the mercury pushed above the 40⁰C (104⁰F) mark and even reached 50⁰C (122⁰F) one day. The biological effects of physical exertion in high ambient temperatures are important to understand, especially if you plan on doing something like the Transcontinental Race.

Slowed down by Lucifer

Over exertion in the heat can increase core body temperature to an abnormal level and lead not only to a significant reduction in performance but more importantly to heat-related illnesses, such as heat stress, exhaustion and stroke. While these differ in severity, they share symptoms, including muscle weakness, dizziness, nausea and loss of appetite. I was acutely aware of the dangers of over-exerting myself in the heat, but because I was in a race, I did it anyway: competition is known to cause competitors to focus on the race so much they ignore sensory cues! That’s how I ended up climbing mountain roads that were not tree lined, in more than 40⁰C (104⁰F). Climbing up against the pull of gravity means the body has to work harder and consequently, generate more heat. You also go slower uphill, meaning there is limited moving air to evaporate sweat and cool the skin. The data I’ve collected show how temperature affected my performance.

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Take a look at these two climbs (in grey), that I did quite early in the race, on consecutive days: Timmelsjoch in Austria followed by Monte Grappa in northern Italy. If we look closely we can see that on average, temperature (orange) was much higher when I climbed Monte Grappa than when I climbed Timmelsjoch. And whilst heart rate (red) is similar, power output (white) is much lower during the climb to the summit of Monte Grappa – I even stopped completely to cool down. A decrease in power output could be attributed to fatigue from the first climb, except that I did much better on another huge climb even later in the race… when the average temperature was much lower!

Your body in a heat wave

At ‘normal’ temperatures, 10-25⁰C (50-77⁰F), exercise feels comfortable; if temperature increases to over 35⁰C (95⁰F), the same intensity of exercise gets more difficult and cannot be maintained as long. Why? In both settings, exercise increases the amount of heat produced by our metabolism, but the way the body copes with it is affected by the temperature. In lower temperatures there is a large difference between the body temperature (high) and ambient temperature (low). Heat naturally travels down a thermal energy gradient towards the lower temperature environment so the body gets rid of the extra heat easily (using convection, conduction and radiation for those of you who did GCSE Physics). In addition, and to facilitate greater heat loss, sweating allows the surface of the skin to cool when sweat evaporates; this process relies on the energy state change: evaporation of liquid sweat into gas uses up heat, leaving the skin cooler. Now, when the ambient temperature is above the core temperature the human body, the usual processes of convection conduction and radiation happen very slowly, if at all. The body then relies a lot more on sweating; however, sweating too much causes dehydration and excessive loss of salt and minerals called electrolytes, with severe implications for performance and health (Cheuvront et al., 2010).

For example, in hot conditions blood vessels near the skin dilate, allowing blood to flow closer to the surface of the skin to cool it down – hence the red face. Heart rate increases to help fill these now larger blood vessels, yet because of sweating and dehydration, blood volume and blood pressure go down, making it even harder to fill the heart: the volume pumped per heart beat actually becomes smaller! This creates stress on the heart whilst it works hard to pump blood to all of the body’s tissues and organs. These constraints definitely place a limit to how much humans can safely exert themselves in the heat (Gonzalez-Alonso et al., 2008)!

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Beating the heat

It is worth noting that a person’s ability to cope with high temperatures during physical exertion is not set and can be improved by training. For example, a two-week acclimation protocol of training at 40⁰C (104⁰F) ambient temperature can lead to increased sweating, retention of electrolytes by sweat glands and expanded plasma volume, all of which compensate, to a degree, for the problems highlighted above. But it’s important to note that you would need to drink more water, not less. It is a common misconception that acclimatising to heat means having to drink less water!

As for me, heat wasn’t the only thing that gave me trouble during the Transcontinental Race… tune in next week for a new episode.


Make sure you follow the blog and subscribe to our Youtube Channel to keep up with the Ultra Cycle Diaries. Check back every Wednesday for a new blog and video!

References

Cheuvront SN, Kenefick RW, Montain SJ & Sawka MN. (2010). Mechanisms of aerobic performance impairment with heat stress and dehydration. J Appl Physiol (1985) 109, 1989-1995.

Gonzalez-Alonso J, Crandall CG & Johnson JM. (2008). The cardiovascular challenge of exercising in the heat. J Physiol 586, 45-53.

Sir Roger Bannister and Exercise Physiology

Bannister_publicdomain_600pxBy Mark Burnley, University of Kent, UK.

On Saturday March 3, 2018, Sir Roger Bannister, the first person to run a mile in under 4 minutes, passed away. His run on the Iffley track in Oxford in May 1954 was one of the defining athletic feats of the 20th century. In reading Bannister’s autobiography, however, it is striking just how much one man managed to pack into life, and how relatively little of it was concerned with athletic performance. He was an amateur athlete whose career pathway was already chosen, and that career was clinical medicine.

Sir Roger Bannister was a neurologist first and an athlete second. This goes some way to describing how good he was at neurology! He published 81 papers on the part of our nervous system that controls involuntary actions like breathing (called the autonomic nervous system). He also wrote and edited several texts on disease in this system.

Bannister’s investigations of the physiology of the respiratory system during exercise took place during a research scholarship in the University Oxford’s Laboratory of Physiology in 1951. It may surprise you to know that this had nothing to do with his interest in athletics. Bannister was instead interested in respiratory control, and exercise was merely a means of testing stress placed on this system. This work was published in The Journal of Physiology in 1954.

In this study, he explored the effect of oxygen levels on the movement of air in and out of the lungs (called ventilation), and on physical performance. To do this he had participants, including himself, run at constant speeds and breathe room air, with 33%, 66%, and 100% oxygen. At the time, the reason for the reduction in ventilation and improvement in physical performance when breathing oxygen-enriched gases was not clear.

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Roger Bannister in 2009. © Pruneau / Wikimedia Commons, via Wikimedia Commons

Each of Bannister’s four participants is identified by initials, which is of course not allowed now. We know of three for certain (Bannister and his supervisor, Dr Dan Cunningham, who co-authors the paper, as well as Norris McWhirter [N.D.McW]). The latter was able to run with relative ease breathing 66% oxygen, and only terminated the treadmill test because “he had a train to catch”!

Throughout the paper, Bannister seems to interpret his results as a clinician: the participant’s subjective experiences of the tests seem almost as important as the respiratory variables themselves. In light of the sometimes extreme volume of data modern laboratory technology can produce, we shouldn’t forget to ask participants in physiological research how it felt.

Physiological research requires interactions with people in other ways too. In his acknowledgements, Bannister thanks, among others, Prof. Claude Douglas for help and advice. Where would exercise physiology be without Douglas? Everybody stands on the shoulders of giants. Even other giants do.

Sir Roger Bannister was special because he was an ordinary man who produced an extraordinary life’s work: on the track, in the laboratory, as a patron and administrator in sport and sports medicine, and in his clinical practice. His humanity shone through in everything he did, and his The Journal of Physiology papers are no different. Thanks for everything, Sir Roger.

The Ultra Cycle Diaries – Setting off on the Transcontinental Race

By Daniel Brayson, King’s College London, @DrDanBrayson

At 21:59 pm on the 28 July 2017, I was sat on the saddle of my bike in the market square in Geerardsbergen, Belgium. One minute later I was racing my bike up a famous steep cobbled path called the Muur of Geraardsbergen hoping to complete challenge of a lifetime!

My name is Daniel Brayson, and most of the time I perform lab experiments at King’s College London, investigating the causes of a heart muscle disease called cardiomyopathy. By nature I am a restless individual and being confined to the lab environment, while a worthy cause, can lead me to become, well… restless! I like the notion of travel and adventure and have always considered myself an active individual. It was these traits which led me to take on the Transcontinental Race.

A self-supported race across Europe

The Transcontinental Race is the most notable of many emerging self-supported ultra-endurance cycle races. It traverses Europe from west to east, eating up 3500 – 4000 km depending on the route, which is never the same from one year to the next. It begins in Geraardsbergen in Flemish Belgium, finishing in previous years in Canakkale, Turkey and more recently at the UNESCO site of the ancient monasteries of Meteora, Greece.
The race is a series of checkpoints between which the route taken is the decision of the rider. As well as endurance fitness, this race tests mapping and planning skills: it is a survival race rather than a mere bike race, orienteering on two wheels if you will, which for many is part of the appeal.

Unlike stage racing with a daily start and finish time (i.e. the Tour de France), when the clock starts in the Transcontinental Race, it does not stop until you cross the finish line. It is at the discretion of the rider to decide when and where to stop, eat and sleep and is completely self-supported. One can use commercial outlets to buy supplies and even stay in hotels, as they are available to all other riders. However, the use of support teams, stopping at international friends’ houses en-route, or posting supplies to various points along your route, is strictly forbidden. All of these factors increase the logistical complexity of the race and it means that anything one may lack in physical fitness could well be compensated for with experience and know-how. Again, for many, this is part of the appeal.

A physical and psychological challenge

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Riders are subjected to a unique set of demands and conditions during such races. Physically, increasing levels of fatigue may seem like an obvious hurdle to success, but experiencing this on the backdrop of having to think about your nutritional, rest and sleep requirements is also psychologically demanding. Environmental challenges such as extreme temperatures – hot days and cold nights – add to the demands, as does topography: climbing mountain roads is a challenge, but even more so above 2000 metres where oxygen starts to become sparse! Needless to say, that as a scientist I viewed these challenging demands as an exciting opportunity to try to observe and quantify the effect these have on the body in the field. So I did…

A physiological case study

Inspired by famous historical proponents of field and self-experimentation such as Griffith Pugh, who conducted field work into altitude physiology, discovering the secrets that put the first man on the summit of Everest, and Barry Marshall, who fed himself bacteria to prove the origins of stomach ulcers (and won a Nobel prize), I armed myself with a few lightweight gadgets before heading to the starting line of the 2017 Transcontinental Race.

The gadgets I had stowed away included a small device to measure sugar and fat from blood samples taken from pricking my finger, and a pulse oximeter, a device that clips onto the end of one’s finger to measure the percentage saturation of oxygen in the blood. On my smartphone, I had downloaded a cognitive test called the Stroop Test, to assess mental fatigue. I also had a bike computer that recorded metrics like heart rate, distance, elevation climbed and environmental temperature.

To find out if I was able to finish the race, tune in to the next episodes where I’ll take a more detailed look at the impact of ultra-endurance racing on my physiology!


Make sure you follow the blog and subscribe to our Youtube Channel to keep up with the Ultra Cycle Diaries. Check back every Wednesday for a new blog and video!

The shear effect of exercise

By Abigail Cook, University of Leeds, @abbycook94

Exercise is good for you. We see this statement daily in one form or another, whether it’s on social media, as advice from medical professionals or making headlines in the news. We know it’s good for our hearts, keeping our weight under control and is even beneficial for our mental health. A question I am often asked is: why is exercise so good for us? My research focuses on the effect of exercise on human arteries and the cells lining these arteries.

Helping blood vessels saves the heart

Cardiovascular disease (CVD) is one of the leading causes of death in the Western world and is responsible for 25% of all deaths in the UK (BHF, 2017). Only 60% of CVD cases, however, can be explained by traditional risk factors such as fat, high blood pressure, and diabetes (Mora et al., 2007). Of the rest, changes to blood vessels appears to play a major part.

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Thus, targeting blood vessels appears to be an attractive way to reduce poor functioning of the blood vessels and CVD. As exercise directly impacts blood pressure, heart rate and the quantity of blood leaving the heart per beat, it provides a method of reaching this target without using drugs.

This is especially important given that physical inactivity is the fourth highest risk factor for mortality worldwide. Also physical fitness, when assessed by aerobic capacity (the maximum oxygen consumption in an exercise session), is the strongest predictor of death in populations with and without CVD.

The scene inside our blood vessels

For the appropriate amount of blood to be delivered to our organs and tissues, arteries need to widen appropriately. One of the key molecules that tells the arteries to widen is nitric oxide (NO). NO is produced by the inner lining of the blood vessel. Its release is controlled by the force, which I study in the lab, called shear stress, applied by blood to this lining.

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Shear stress can be characterised in different ways, with each form resulting in different responses from the inner lining of the vessels. High levels of unidirectional shear stress occur in the straight sections of blood vessels. This is associated with the production of molecules that fight inflammation, which protect the cell from abnormal growth and proliferation, and even cell death. Low levels of bidirectional shear stress are most often found at curvatures and at branches of blood vessels. This type of shear stress generates molecules that are associated with inflammation.

The areas that are exposed to low levels bidirectional shear stress are at the greatest risk of developing atherosclerosis (a type of CVD), the disease where an artery becomes narrowed due to the build-up of plaques. Prolonged exposure to this type of shear stress can lead to dysfunction of the inner lining of blood vessels, which is an early indicator of CVD.

Exercise lends a helping hand

The ideal shear stress throughout the vasculature to minimise the likelihood of developing CVD such as atherosclerosis would be high levels of unidirectional shear stress. One way of increasing shear stress is by exercising.

Exercise increases heart rate, cardiac output, blood flow, and thus shear stress. Undertaking regular exercise has been shown to be protective against atherosclerosis and slow down the progression of CVD. It is unclear, however, what type of exercise training is most beneficial to the blood vessels. Continuous exercise may provide steady levels of shear stress, whereas interval exercise may allow shear stress to vary throughout exercise from a low to a high level.

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My research uses ultrasound and MRI technology to understand the patterns and levels of shear stress applied to arteries during differing exercise protocols. The arteries of interest are both are susceptible to developing atherosclerosis (the aorta and the common femoral artery), and they can be monitored during an exercise protocol.

This is especially important in the common femoral artery as it is directly supplying blood to the working muscle during exercise. Then, I am examining what happens when these patterns and levels are replicated in cells grown in the laboratory, in order to see which type of exercise enhances cell function most effectively.


BHF. (2017). Cardiovascular Disease Statistics 2017. BHF.

Mora S, Cook N, Buring JE, Ridker PM & Lee IM. (2007). Physical activity and reduced risk of cardiovascular events: potential mediating mechanisms. Circulation 116, 2110-2118.