Changes in balance and joint position sense during a 12-day high altitude trek: The British Services Dhaulagiri medical research expedition.

Sarah B Clarke,John P O’Hara,Kevin Deighton,Gareth Nicholson,David R Woods,Liam Gallagher,Christopher J Boos,Caroline Newman,Adrian Mellor,Yu Ru Kou

doi:10.1371/journal.pone.0190919

Abstract

Postural control and joint position sense are essential for safely undertaking leisure and professional activities, particularly at high altitude. We tested whether exposure to a 12-day trek with a gradual ascent to high altitude impairs postural control and joint position sense. This was a repeated measures observational study of 12 military service personnel (28±4 years). Postural control (sway velocity measured by a portable force platform) during standing balance, a Sharpened Romberg Test and knee joint position sense were measured, in England (113m elevation) and at 3 research camps (3619m, 4600m and 5140m) on a 12-day high altitude trek in the Dhaulagiri region of Nepal. Pulse oximetry, and Lake Louise scores were also recorded on the morning and evening of each trek day. Data were compared between altitudes and relationships between pulse oximetry, Lake Louise score, and sway velocity were explored. Total sway velocity during standing balance with eyes open (p = 0.003, d = 1.9) and during Sharpened Romberg test with eyes open (p = 0.007, d = 1.6) was significantly greater at altitudes of 3619m and 5140m when compared with sea level. Anterior-posterior sway velocity during standing balance with eyes open was also significantly greater at altitudes of 3619m and 5140m when compared with sea level (p = 0.001, d = 1.9). Knee joint position sense was not altered at higher altitudes. There were no significant correlations between Lake Louise scores, pulse oximetry and postural sway. Despite a gradual ascent profile, exposure to 3619 m was associated with impairments in postural control without impairment in knee joint position sense. Importantly, these impairments did not worsen at higher altitudes of 4600 m or 5140 m. The present findings should be considered during future trekking expeditions when developing training strategies targeted to manage impairments in postural control that occur with increasing altitude.

Highlights

Travel to high altitude among lowlanders has become increasingly common for both professional and leisure purposes
It has been suggested that these syndromes manifest along a spectrum transitioning from acute mountain sickness (AMS) to high altitude cerebral edema (HACE) with the presentation of serious neurological impairments such as balance and postural control [3]
No participants were treated with prophylactic acetazolamide (Diamox1), and no other medications were used for AMS or which would have interfered with balance or the central nervous system

Summary

Introduction

Travel to high altitude among lowlanders has become increasingly common for both professional and leisure purposes. Trekking in Nepal has become one of these popular high altitude adventurous activities; the number of trekking permits obtained by foreigners rose from 14000 in 1985 [1] to 97185 in 2014 [2]. It has been suggested that these syndromes manifest along a spectrum transitioning from AMS to HACE with the presentation of serious neurological impairments such as balance and postural control [3]. Travelling over dangerous mountainous terrain has its own inherent risks, and compounding this with these impairments in balance and postural control makes the trekker vulnerable to trips or falls [5]

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Conclusion