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Centre for Human Performance

British Services Dhaulagiri Medical Research Expedition

The British Services Dhaulagiri Medical Research Expedition 2016 was a large-scale research collaboration between the Defence Medical Services and Leeds Beckett University. It investigated the effects of high-altitude exposure on the human body.

British Services Dhaulagiri Medical Research Expedition

The Challenge

Exposure to high-altitude environments, places significant stress on the human body. This is due to the reduction in the partial pressure of oxygen with increasing altitude. If an individual does not acclimatise appropriately at a given altitude this can manifest in altitude illness. In certain circumstances this can be life threatening. Thus, it is important to establish the human bodies response to high-altitude in real life scenarios to predict and understand the occurrence of altitude illness. We have a specific interest in cardiovascular, and hormonal responses to high-altitude and how these can be used to predict altitude illness. This allows us to develop interventions to reduce the burden of altitude illness. The challenge is also to assist mountaineers and military personal to enhance their performance and maintain their health.

Pre-acclimation using normobric hypoxia and apnoea training has been proposed as a solution, but the optimal protocols have yet to be developed and warranted further investigation. In addition, we know that appetite and energy intake is suppressed at altitude, which can negatively affect lean mass and exercise performance. However, field studies assessing the mechanisms associated with appetite suppression were lacking.

THE APPROACH

This high-altitude medical research was wide ranging investigating:

  • The effects of acclimation (simulated normobaric hypoxia, apnoea training) on performance
  • Biomechanical changes in walking and balance
  • Appetite responses; cardiac rhythm
  • Central blood pressure; heart rate variability
  • Hormonal marks of altitude illness
  • The effect of iron infusion on the ability to cope with high altitude exposure
  • Research was carried out with the main military team aiming to climb Dhaulagiri (8,167m), the 7th highest peak in the World, in a testing and challenging Alpine style. In addition, eight medical research trek teams completing the Dhaulagiri circuit took part. Following baseline measurements in the UK, each trekking team who departed Kathmandu several days apart visited three research camps at increasing altitudes, taking part in the most comprehensive medical research expedition to high-altitude of its kind

This project presented a substantial logistical challenge with half a ton of research and medical equipment being shipped to Nepal from Leeds to establish the research camps. Honda provided us with generators to power our equipment in such an austere environment. Use of dewars filled with liquid nitrogen allowed us to rapidly freeze and store biological samples and contributed to a ‘cold chain’ stretching all the way from Nepal to our laboratory facilities in Leeds.

THE IMPACT

We were able to establish that high-altitude places significant stress on the heart with exposures above 4000m associated with significant brady- and tachyarrhythmias, supporting a potential proarrhythmic risk. However, no link was detected between high-altitude and sustained ventricular arrhythmias linked to an increased risk of sudden cardiac death. In addition, we showed increases in certain central blood pressure variables, which were related to sympathetic activation associated with high-altitude exposure, rather than any genuine change in arterial stiffness. This has impacted our screening procedures when recruiting participants, whereby we now assess their heart function before we exposure them to altitudes above 4000m. 

High altitude was shown to impair postural control, which is important in terms of a heighten risk of falling on rough terrain whilst trekking or climbing at high-altitude. Our research was the first to demonstrate that changes in plasma acylated and total ghrelin concentrations may contribute to the suppression of appetite. An understanding of the mechanisms of appetite suppression, will help in the development of specific nutritional interventions to maintain appetite and energy balance during expeditions to high-altitude. 

The above provides a glimpse of some of the novel findings from this research. For additional information, please see our publications from this project, which are highlight below. 

 

Publications

  •  Hill, N. E., Deighton, K., Matu, J., Misra, S., Oliver, N. S., Newman, C., O'Hara, J., . . Woods, D. (2018). Continuous glucose monitoring at high altitude - Effects on glucose homeostasis. Medicine and Science in Sports and Exercise, 50(8), 1679-1686. doi:10.1249/MSS.0000000000001624
  • Cooke, M., Cruttenden, R., Mellor, A., Lumb, A., Pattman, S., Burnett, A., O'Hara, J.P., . . 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. doi:10.1177/1470320318782782
  • Clarke, S., Deighton, K., Newman, C., Nicholson, G., Gallagher, L., Boos, C., . . . O'Hara, J. P. (2018). Changes in balance and joint position sense during a 12-day high altitude trek: The British Services Dhaulagiri medical research expedition. PLoS ONE, 13(1). doi:10.1371/journal.pone.0190919
  • Howard, M., Bakker-Dyos, J., Gallagher, L., O'Hara, J. P., Woods, D., & Mellor, A. (2017). Power Supplies and Equipment for Military Field Research: lessons from the British Service Dhaulagiri Research Expedition 2016. Journal of the Royal Army Medical Corps. doi:10.1136/jramc-2017-000767
  • Mellor, A., Bakker-Dyos, J., Howard, M., Boos, C., Cooke, M., Vincent, E., O'Hara, J. P., . Woods, D. (2017). The British Services Dhaulagiri Medical Research Expedition; A unique military/civilian research collaboration. Journal of the Royal Army Medical Corps, 163(3), 371-375. doi:10.1136/jramc-2016-000700
  • Matu, J., O'Hara, J., Hill, N., Clarke, S., Boos, C., Newman, C., . . . Deighton, K. (2017). Changes in appetite, energy intake, body composition and circulating ghrelin constituents during an incremental trekking ascent to high altitude. European Journal of Applied Physiology, 1-12. doi:10.1007/s00421-017-3683-0
  • Boos, C., Holdsworth, D., Woods, D., O'Hara, J., Brooks, N., Macconnachie, L., . . . Mellor, A. (2017). Assessment of Cardiac Arrhythmias at Extreme High Altitude Using an Implantable Cardiac Monitor: REVEAL HA Study. Circulation, 135(8), 812-814. doi:10.1161/CIRCULATIONAHA.116.026584
  • Boos, C., Vincent, E., Mellor, A., Woods, D., Newman, C., Cruttenden, R., . . . O'Hara, J. (2017). The effect of high altitude on central blood pressure and arterial stiffness. Journal of Human Hypertension. doi:10.1038/jhh.2017.40
  • Boos, C., Vincent, E., Mellor, A., O'Hara, J. P., Newman, C., Cruttenden, R., . . . Woods, D. (2017). The effect of Sex on Heart Rate Variability at High Altitude. Medicine and Science in Sports and Exercise. doi:10.1249/MSS.0000000000001384

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