Performance in Extreme Environments 

“We believe in translational science, with the aim of maximising performance and reducing morbidity in extreme environments”.

This interdisciplinary theme brings together experts from the fields of biochemistry, endocrinology, cardiovascular function, energy metabolism, aviation medicine, exercise physiology, nutrition, psychology and biomechanics. 

Our research examines human responses to altitude exposure at ‘terrestrial altitude’ and within simulated (hypobaric and normobaric hypoxic) environments, as well as thermoregulation and the application of apnoeic principles. A high proportion of our field research has been supported by our close working relationship with the Defence Medical Services and Carnegie Great Outdoors, who we have worked with us on several research expeditions in recent years.

our projects

our research community

The performance in extreme environments research community includes academic colleagues and postgraduate researchers who are involved in a variety of projects with wide-reaching impact.

Postgraduate research students

Commenced October 2018

In high-performance sports marginal differences are often seen to yield great rewards. Previous research in competitive sports, such as free diving and cycling, has suggested that the use of acute and chronic apnoeas (the cessation of breathing) can improve performance. During breath holds hypoxemia occurs in the spleen, potentially causing a contraction and subsequently increasing the number of circulating erythrocytes. Other physiological responses are based upon the mammalian diving response and the primary function of oxygen preservation. These responses combined with an increase in acidosis tolerance are hypothesised to lead to improved performance. This PhD focusses on the link between apnoeas and competitive swimming, exploring the possibility of finding great rewards from marginal gains.


  • Robertson, C., Lodin-Sundström, A., O’Hara, J., King, R., Wainwright, B., and Barlow, M. (2020). Effects of pre-race apnoeas on 400-m freestyle swimming performance. J Strength Cond Res 34(3): 828–837.

Commenced February 2018

Athletes competing at major sporting events, were the conditions are hot-humid, often experience a reduction in exercise capacity related to hyperthermia-induced fatigue. As such, this PhD aimed to develop heat-alleviating strategies which reduce the negative impact heat has on endurance performance. More specifically, heat acclimation interventions for triathletes competing at the Tokyo 2021 Olympics. In addition, this PhD is looking to developed a heat stress test to better understand individual athlete responses and monitor the effectiveness of heat-alleviating strategies. Findings from this thesis may be used by support staff and athletes prior to competition in the heat to optimise performance. This PhD is in partnership with the English Institute of Sport / British Triathlon Federation.


  • Snape D., Wainwright B., Woods D.R., Needham L., O’Hara J. (2020). Reliability of blood biomarkers of physiological stress at rest and in response to exercise under hot-humid conditions. Future Physiology Conference 2020.

Commenced October 2016

Footballers are often required to perform in hot, humid conditions, particularly during major competitions in summer. Success is dependent upon athletes’ ability to maintain consistently high physical performance levels and simultaneously make split-second decisions in dynamic environments. The debilitating effects of heat exposure on prolonged high-intensity exercise are generally understood, however the effects on cognitive function are less known. This PhD investigated how heat exposure may affect decision-making ability and how central mechanisms (i.e., catecholamine alterations) may influence these effects. Additionally, it examined whether acute tyrosine supplementation could augment any decrements observed. Findings may help optimise football specific decision-making and performance in hot environments.


  • FEPSAC (Muenster, 16th July, 2019): The effect of physical fatigue and heat on cognitive function during high-intensity intermittent exercise in team sport players

Completed February 2020

Mountaineers and military personnel often experience a reduction in physiological capability when ascending to high altitude. As such, this PhD aimed to develop nutritional strategies to overcome the debilitating effects on operational capability and endurance performance in such conditions. Specifically, this PhD identified breakfast consumption and carbohydrate supplementation as strategies to induce beneficial alterations in substrate oxidation during exercise in hypoxia. Further, both strategies also provide appropriate tools for augmenting energy intake at high altitude and avoiding a hypoxic induced reduction in muscle mass. Findings from this thesis may be used by mountaineers and military personnel during high altitude sojourns to optimise performance.

Publications from PhD (to date):

  • Griffiths, A., Shannon, O.M., Matu, J., King, R., Deighton, K., O’Hara, J.P. (2019) The effects of environmental hypoxia on substrate oxidation during exercise: a meta-analysis. Journal of the International Society of Sports Nutrition. 16 (10)
  • Griffiths, A., Deighton, K., Shannon, OM., Matu, J., King, R., O'Hara, J.P. (2019) Substrate oxidation and the influence of breakfast in normobaric hypoxia and normoxia. European Journal of Applied Physiology. 119 (9). 1909-1920.
  • Griffiths, A., Shannon, O.M., Matu, J., King, R., Deighton, K., O’Hara, J.P. (2019) Response: Commentary on the effects of hypoxia on energy substrate use during exercise. Journal of the International Society of Sports Nutrition. 16
  • Griffiths, A., Deighton, K., Shannon, O.M., Boos, C., Rowe, J., Matu, J., King, R., O’Hara, J.P. (2020) Appetite and energy intake responses to breakfast consumption and carbohydrate supplementation in hypoxia. Appetite. 147

Completed November 2018

This PhD aimed to provide an insight to the underlining physiological characteristics and mechanisms that enables elite breath-hold divers to sustain long apnoeic durations and examine to what extend these stemmed from an apnoea-specific, training-induced stimulus. This was attained through (1) comparing their resting characteristics and physiological responses to maximal static/dynamic apnoeas with non-divers, and (2) investigating the long-term effects of apnoeic training. Collectively, this PhD signified that the ability to achieve long apnoeic durations primarily rests upon two fundamental principles including, an enhanced oxygen storage and conservation capacities, both of which originate from a training-induced stimulus.

Publications from PhD (to date):

  • Elia, A., Wilson, O. J., Lees, M., Parker, P., Barlow, M. J., Cocks, M. & O’Hara, J. P. (2019) ‘Skeletal muscle, haematological and splenic volume characteristics of elite breath-hold divers’, European Journal of Applied Physiology. 119(11-12):2557-2565. doi: 10.1007/s00421-019-04235-1
  • Elia, A., Barlow, M., Deighton, K., Wilson, O. & O’Hara, J. (2019) ‘Erythropoietic responses to a series of dynamic and static apnoeas in elite and non-breath-hold divers’, European Journal of Applied Physiology. 19(11-12):2499-2511. doi: 10.1007/s00421-019-04230-6

List of Conference Communications

  • Elia, A., Wilson, O., Parker, P., Barlow, M., Cocks, M., O’Hara, J. Skeletal muscle capillarisation and myoglobin are higher but mitochondrial content is similar in elite breath-hold divers versus non-divers. Europhysiology, 14th-16th September, 2018, London.
  • Elia, A., Barlow, M., Deighton, K. & Wilson, O., O’Hara, J. Serum erythropoietin concentrations post a series of repeated maximal dynamic and static apnoeas in elite and non-divers. European College of Sport Science, 4th - 7th July, 2018, Dublin.

Completed November 2017

When an individual ascends to high altitude it seems inevitable they will lose body mass, likely due to a loss of appetite. This can reduce their performance in dangerous environments. Jamie's PhD programme investigated the magnitude and mechanisms of altitude-induced anorexia through a systematic review and meta-analysis, a laboratory study, and a field study in Nepal. Finally, his fourth and final study investigated a dietary intervention which successfully minimised this anorexia during exercise at altitude.

PhD Publications

  • Matu, J., Gonzalez, J., Ispoglou, T., Duckworth, D. & Deighton, K. (2018) The effect of hypoxia on appetite, gut hormones and energy intake: a meta-analysis. Appetite. 31, 98 – 108.
  • Matu, J., Deighton, K., Ispoglou, T. & Duckwoth, L. (2017) The effect of moderate versus severe simulated altitude on appetite, gut hormones, energy intake and substrate oxidation in men. Appetite. 113, 284-92.
  • Matu, J., O’Hara, J., Hill, N., Clarke, S., Boos, C., Newman, C., Holdsworth, D., Ispoglou, T., Duckworth, L., Woods, D., Mellor, A. & Deighton, K. (2017) Appetite, energy intake, ghrelin and body composition responses to a high altitude trek: the British Services Dhaulagiri Medical Research Expedition. European Journal of Applied Physiology. 117, 1917-1928.
  • Matu, J., Deighton, K., Ispoglou, T., Shannon, O. & Duckworth, L. (2017) The effect of a high carbohydrate versus a high fat breakfast on appetite, appetite hormones and energy intake in normobaric hypoxia. Physiology and Behaviour. 117, 353-60.

PhD published conference abstracts

  • Matu, J., Deighton, K., Ispoglou, T., Shannon, O. & Duckworth, L. (2017) Consumption of a high fat breakfast attenuates the suppression of appetite and acylated ghrelin during exercise at 4300m simulated altitude. 22nd Annual Congress of the European College of Sport Science, Essen. European Journal of Sport Science. Oral presentation nominated for Young Investigator Award.
  • Matu, J., Deighton, K., Ispoglou, T. & Duckworth, L. (2016) The Effect of Normobaric Hypoxia on Appetite, Appetite Regulating Hormones & Energy Intake. 21st Annual Congress of the European College of Sport Science, Vienna. European Journal of Sport Science. Mini-oral presentation nominated for Young Investigator Award.


Military personnel are deployed and required to perform operationally at high altitude. The North Atlantic Treaty Organisation (NATO) has acknowledged the risk of fighting in mountainous areas and that high, mountainous areas provide sanctuary for hostile forces, particularly terrorist organisations. High altitude exposure significantly impacts performance and can lead to life threatening conditions for both military personal and Mountaineers. This PhD evaluated the use of intermittent normobaric hypoxia as a means of acclimation and pre-acclimatisation prior to high terrestrial altitude exposure. This included assessment of ventilatory, endocrine and cardiopulmonary variables associated with altitude acclimatisation, exercise performance and health.


  • Cooke, M., Cruttenden, R., Mellor, A., Lumb, A., Pattman, S., Burnett, A., Boot, C., Burnip, L., Boos, C., O’Hara, J. and Woods, D. (2018). A pilot investigation into the effects of acute normobaric hypoxia, high altitude exposure and exercise on serum angiotensin-converting enzyme, aldosterone and cortisol. Journal of the Renin-Angiotensin-Aldosterone System, 19(2). doi:10.1177/1470320318782782


  • Cooke, M., Boos, C., Holdsworth, D., Mellor, A., Bradley, R., O'Hara, J., & Woods, D. (2019). Cardiopulmonary acclimation using intermittent normobaric hypoxic exposure with and without exercise. In Extreme Environmental Physiology: Life at the limits, physiological society. Portsmouth.
  • Cooke, M., Boos, C., Holdsworth, D., Mellor, A., ,Bradley, R., O'Hara, J., & Woods, D. (2019). Pulmonary Artery Systolic Pressure and High-altitude pulmonary oedema susceptibility in normobaric hypoxia. In British Mountain Medicine Society Conference. Sheffield.
  • Cooke, M., O’Hara, J. & Woods, D. (2016) Optimising performance at high altitude, The Royal Society of Medicine, Non-conventional warfare: the medical response, organised by the military medicine section. In Royal Society of Medicine (Sports and Exercise Medicine section). London.
  • Cooke, M., O’Hara, J. & Woods, D. (2016) Cortisol responses to intermittent normobaric hypoxic exposure with and without exercise. 8th European hypoxia symposium: High altitude and isobaric hypoxia influence on human performance, science and practice: NATO mountain warfare centre of excellence. Slovenia.

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The entrance Carnegie School of Sport building and outdoor seating area on Headingley Campus

We have two state of the art environmental chambers, capable of achieving altitudes over 8000m, temperatures between –30 and +50 degree C and relative humidity of 15 to 95%.  

Research outputs



contact Professor John o'Hara