Bio: PhD student Ollie Page

Ollie joined Newcastle University as a Graduate Teaching Assistant, starting a PhD in thermal physiology and diabetes at the beginning of 2022. He graduated from the University of Chichester with a BSc in Sport and Exercise Science in 2019. While in Chichester Ollie worked for the Occupational Performance Research Group alongside the Institute of Naval Medicine and British Armed Forces to assess physical employment standards, while also investigating the influence of extreme heat on gut function during exercise. Ollie then completed an MSc in Exercise Physiology from Loughborough University in 2021 and continued investigating extreme environments in his dissertation entitled ‘Induction and decay of LHTH/LHTL mediated adaptations and the optimisation of sea-level endurance performance in athletes: a systematic review and meta-analysis’.

With a childhood based around professional football, and simultaneously involving myself in multiple land and water sports, I have had many experiences of undertaking elite sport in challenging environments. Though no longer competing, my research in Exercise Physiology has led to trying to further improve athlete performance within challenging environments, whether heat or altitude.

Ollie’s PhD will focus on increasing our understanding of how thermal strain impacts the cardiovascular and metabolic responses in clinical patients with Type 1 and Type 2 Diabetes who typically present with increased vulnerability in hot climates. He will also explore mitigation strategies to alleviate the health risks posed by extreme heat.

Bio: PhD Student Lee Ager

Lee joined Newcastle University as a Graduate Teaching Assistant starting a PhD in thermal physiology at the beginning of 2022. He is a previous engineering graduate from Newcastle University and initially started his professional career working as a Structural Engineer for ten years before his passion for Exercise Physiology brought him back to Newcastle University once again. Lee graduated in 2021 with a BSc in Sport & Exercise Science (SES). Lee’s PhD will focus on how thermal impulse acutely impacts physiological strain, adaptation and exercise tolerance to extreme heat stress. The aim is to provide evidence-based guidance for exercising as well as optimising how we prepare individuals for extreme hot and humid conditions. 

As a keen cyclist, Lee’s interest in thermoregulation in the heat stemmed from having witnessed first-hand the impact severe environmental conditions can place on the human body while competing. Lee regularly takes part in cycling events with a typical season focusing on the National Hill Climb Championship. Lee also coaches a number of amateur cyclists, runners and triathletes and particularly enjoys applying the knowledge gained from his research to prepare his athletes for racing in challenging environmental conditions.

Blog: Why is the Kona IronMan World Champs so hard for the pros?

Hawaii is the birth place of the IronMan triathlon where in 1978 Judy and John Collins challenged individuals to swim bike and run 140.6 miles and joked they would call the winner an “Iron man”. The event now sees 1000s of athletes test themselves in IronMan races all over the globe, including myself. But Kona, home to the Ironman World Championships which begins today (6th October 2022), holds something special for all triathletes. The history of the race is full of epic tails of survival (see the story of Julie Moss or Sian Welsh & Wendy Ingraham) and infamous battles such as the Iron War (between Dave Scott and Mark Allen). The weather is generally consistent and therefore predictable in Kona in October: sunny, windy and humid. However, while the air temperatures are generally around 30 oC which are not necessarily remarkable, it is the humidity “swamp-like” conditions that really challenge athlete’s thermoregulatory capacity when competing in the Ironman World Championships.

So why is Kona so hard?

It is well established that heat will reduce exercise performance incrementally, mediated by increasing heat gain and a rise in core body temperature. When athletes are faced with hot environments, preparation strategies such as heat acclimation facilitate heat tolerance which drive a range of physiological adaptations to help them tolerate heat. However, it is an adaptive increase in sweat rate that facilitates the greatest heat loss. Heat transfer is mediated by evaporation of sweat from the skin which transfers heat away from the body. In fact, when all sweat is able to evaporate from the skin (we will call this ideal conditions – typically dry-hot) heat is removed at a rate of 2.34 kJ/g. The human body can produce sweat at rates approximating ~ 30 g/min (losses in body mass equivalent to ~ 1.5-2 L/hr). Although, if you have been keeping up to date with Lionel Sanders vlog he mentions much higher changes in body mass after training that indicate sweat losses of ~2.5 L/hr. However, if using our sweat rate value of ~ 30 g/min this equates to removing heat at 73 kJ/min (~1219 W). The human body has only ~ 20% efficiency therefore this reported heat loss would support normothermic total energy use of 1520 W. As a result external work rate would be equivalent to ~ 305 W (20% of total energy use). Athletes across a number of social media platforms discuss numbers in the range of 300-350 W for average sustainable power during the cycling portion of an IronMan, meaning that in ideal conditions these numbers are perfectly reasonable and heat gain can be controlled (being mindful of dehydration of course).

[Post race edit: Sam Laidlow beat bike course record with a time of 4 hr 4 min and reported average power ~315 W. source:].

However, the big problem in Kona, like we have said, is the humidity. Kona may see humidity in the range of 80-90% (30 oC air temp at 90% RH = WBGT ~ 28.6 oC) meaning the air contains a greater amount of water vapor thus reducing the gradient for evaporative heat transfer. This means our ideal scenario no longer holds true and the ability to dissipate heat decreases. It is the efficiency of sweating, defined as the ratio between secreted and evaporated sweat that is reduced as humidity increases, with some studies indicating that efficiency can decrease by ~35 % when humidity increases from 50 to 70% (Alber-Wallerstron & Homer, 1985; Frye & Kamon 1983). Clearly if humidity tops 90% the athlete’s sweat efficiency will be further reduced. As a result, athletes gain heat more quickly, core temperature increases more rapidly reaching critical limits facilitating a drop in exercise intensity and potentially leading to hyperthermia or more serious consequences. Indeed, Jan Frodeno, arguably the best IronMan athlete of all time, famously said that his rule of thumb is to take 15-20% off his normal wattage on the bike to account for the extreme heat stress in Kona.

So, what are the anticipated conditions in Kona?

Over the past 3 days humidity has ranged from 65 to 94% relative humidity, with temperatures ranging from 25-30 oC during the approximate times the professional athletes will race (6am-3pm) ( – accessed 5/10/22 23:00). Whilst athletes and coaches are much more aware of the impact of heat stress and humidity in Kona, we will probably still see the breakdowns and collapses in the professional field that we are so accustomed to seeing at Kona. Science and technology, with respect to maximising heat tolerance, has pervaded the sport in recent years with the Norwegians taking the game to another level and other professionals following suit. It will be fascinating to see who has prepared the best, what strategies they adopt and who’s body can tolerate the conditions best. It will be a great race to watch! My money is on Daniela Ryf or Lucy Charles-Barclay in todays race and in the men’s race on saturday its the Big Blu although really hope Sanders has the race he capable of.

Updated 06/10/22 18:00 – Women’s environmental conditions at start of swim – as predicted 24 oC and 88% humidity.

Updated 08/10/22 – Men’s environmental conditions at start of swim (~6:00am left) and at the start of the run (~10:44am right) – as predicted temps increased from 24 to 28 oC and humidity remained stable around 85%.

Owen Jeffries

Consultancy: Heat acclimation for Marathon Des Sables

We offer consultancy services to facilitate athletes to prepare for extreme climates including extremes in heat, cold and altitude. We recently worked with an athlete preparing for the Marathon Des Sables, called the toughest footrace on earth. MDS is an event that takes place each year in the Sahara Dessert where temperatures can reach up to 50 oC. Carried out over 6 days athletes must complete +250 kms, a massive challenge in some of the most extreme environmental conditions on earth, so much so that in 2021 during extreme heat less than half the 753 athletes that started the race finished and sadly one athlete died.

Athlete exercising in 40 oC 40% humidity, with internal core temperature hitting 39.5 oC in preparation for the MDS event.

If you are interested in consultancy in extreme environments contact: Dr Owen Jeffries []

You can find the full range of services we offer at this link:

Media: Sports scientist who ran Ironman race in 95F shares 5 tips for exercising in extreme temperatures

Dr Owen Jeffries spoke with a reporter from online news outlet following his recent Ironman triathlon competition in Austria which occurred during the European heat wave with temperatures reportedly reaching close to 38 oC.

In the article he discussed 5 tips when preparing or exercising in extreme heat. This included a consideration of mechanisms of adaptation, optimisation of hydration, sodium supplementation, cooling strategies and carbohydrate gut training.

The full article can be found here:

Media: The most effective and cheap ways to cool your body during a heat wave, according to scientists

Dr Owen Jeffries (Newcastle University) and Professor George Havenith (Loughborough University) spoke with a reporter from online news outlet during the extreme heat waves being experienced across America and Europe during the summer 2022.

In the article they explored strategies on how to cool during hot periods of weather implementing simple tasks such as: cooling hands and feet, cold water immersion, spraying clothing with water, eating lighter meals, using electric fans, optimal hydration, and exercising in the heat.

The full article can be found here:

New study: Meta-analysis exploring effects of heat acclimation on VO2max in thermoneutral and hot environments

In our latest study published in Sports Medicine on the 3rd April 2021 led by Dr Mark Waldron (Swansea University), we meta-analysed 28 studies to explore how heat acclimation or acclimatisation can modify maximal oxygen consumption. This is an area of some heated discussion in the literature (see for example the point-counterpoint in J.Physiol here).

To summarise our findings, we found that heat acclimation can enhance VO2max adaptation in thermoneutral or hot environments by at least a small and up to a moderate–large amounts, with larger improvements occurring in the heat.

The article can be found here: 10.1007/s40279-021-01445-6

New study: Sex differences to L-menthol during exercise in a hot environment

Our latest study has been accepted for publication in the journal Physiology & Behaviour on 1st February 2021. The project was led by a student in our laboratory Miss Abbie Parton.

The work expanded on some of our early work first characterising the effect of non-thermal cooling strategies by applying L-menthol (which is perceived as a cooling flavour) mouthrinse and recording beneficial effects in exercise regulation in hot environments (Flood et al. 2017). In this new study we report a sex-specific difference in how females perceive the application of this “non-thermally” cooling L-menthol rinse during exercise in a hot environment. The impact of such findings are crucial for the exploration of ergogenic supplements for use in hot climates particularly when considering the differences between male and female populations.

The article can be found here: 10.1016/j.physbeh.2020.113250

New study: Expert-led consensus statement on the use of Menthol for Tokyo 2021 Olympic games

Dr Owen Jeffries (Newcastle University) along with Dr Martin Barwood (Leeds Trinity University) and Dr Russ Best (Waikato Institute of Technology) led a 14-strong global team of experts in the creation of a consensus statement on the use of menthol in sport. The article was developed following a collaborative meeting at the recent ICEE conference (July 2019) in Amsterdam, in the context of the forthcoming Tokyo 2021 Olympic Games. The article was published in Sports Medicine on 4th July 2020.

The article can be found here (open access): 10.1007/s40279-020-01313-9

New study: Explores the time course of adaptations in thermoneutral VO2max following heat acclimation

In our latest study published in the European Journal of Applied Physiology in September 2019, we report that VO2max in thermoneutral environments can be enhanced following a bout of heat acclimation. Crucially we report that future research should take care when testing athlete post HA as residual fatigue may blunt the maximal responses that can be achieved and that on average confirmatory tests should be performed at least 96hr following the final bout.

This article can be found here: 10.1007/s00421-019-04218-2

Conference: ICEE 2019, Amsterdam

During the XVIII International Conference on Environmental Ergonomics in Amsterdam, Dr Owen Jeffries (Newcastle University, UK) and Dr Martin Barwood (Leeds Trinity University, UK) chaired a symposium on Thursday 11th July 2019 entitled: “The application of menthol in sport, exercise and occupational settings: to apply, ingest or discard?”. Dr Russ Best (Waikato Institute of Technology, New Zealand) and Dr Jason Gillis (Salem State University, Massachusetts, USA) accompanied both Martin and Owen presenting recent findings and exploring unpublished observations expanding our understanding of the use of menthol in hot environments and posing future questions in what was a fascinating discussion.

Pictured (L-R), Dr Jason Gillis, Dr Martin Barwood, Dr Owen Jeffries. ICEE 2019 Amsterdam.