Polar Thigh and Other Medical Observations During the Longest Solo Unsupported One-Way Polar Ski Expedition in Antarctica

Abstract

Antarctic expeditions are exceptional challenges for the human body, and medical issues such as nutritional deficiencies, polar anemia, cold injuries, and even death have been reported. We prospectively investigated medical issues encountered by a 33-year-old female adventurer completing the longest solo unsupported one-way polar ski expedition in Antarctica, covering 1484.53 km in 70 days and 16 h from Hercules Inlet to the Ross Ice Shelf, in temperatures estimated from −12 to −50°C and wind speeds of up to 60 mi/h. The adventurer developed a debilitating overuse musculoskeletal neck injury due to poor environmental conditions (ie, poor visibility, wind, and soft snow) while pulling a heavy sled and continuously holding the neck in a flexed position for checking directions on a mounted compass. The adventurer further developed a cold injury on the left calf (polar thigh) that gradually worsened and became ulcerated and more painful throughout the expedition. Potential risk factors included cold ambient temperatures, exposure to windy conditions, and clothing. After the expedition, this injury was treated with a skin graft. Important changes in body mass were observed (ie, reduction of body mass by 26.7% after the expedition) as well as general fatigue, muscle soreness, and sleep deterioration. This case study contributes to the body of knowledge of medical issues during Antarctic expeditions and provides the first scientific account of an adventurer with polar thigh. Further research into this condition is recommended.

Introduction

The challenges of Antarctic expeditions to the human body are enormous, especially the impact of the harsh environmental conditions, with extreme cold and wind, strenuous trekking activities from sea level to altitude, 24-h daylight, remoteness, sensory deprivation, and large distances to be covered. ¹ Early explorers mostly traveled on foot, accompanied by huskies and ponies, with much of the food and equipment transported by the explorers themselves with little knowledge of the physiologic demands, whereas now Antarctic adventures ski, manhaul, or use kites, often relying on scientific data, modern technology, and equipment. ¹ Nevertheless, some of the physiologic and mental challenges remain, including having to cope with the extreme conditions in the Antarctic while performing strenuous exercise and coping with nutritional demands and malnutrition, hypothermia, high altitude, and sleep deprivation.^2–4

Medical issues have been described during the early (or “heroic”) age of Antarctic explorations and included cold injuries, musculoskeletal injuries, nutritional deficiencies such as beriberi (vitamin B₁ deficiency) and scurvy (vitamin C deficiency), and even death. ⁵ Historically, these dangers were highlighted by the “race to the South Pole.” Both Norwegian explorer Roald Amundsen and British Royal Navy officer Robert Falcon Scott aimed to reach the South Pole first in 1911, with Amundsen and his team succeeding. Scott and his team reached the South Pole approximately 5 weeks later, but all 5 team members died on their return journey to base camp. ¹

Antarctic expeditions remain challenging, pushing the human body to its limits. British Army officer Harpreet Chandi broke 2 Guinness World Records in 2023 for the longest solo unsupported one-way polar ski journey for a woman and overall traveling across Antarctica from Hercules Inlet to the Reedy Glacier, covering 1484.53 km in 70 d and 16 h. ⁶ Chandi surpassed the previous female solo record set by German Anja Blacha, who traveled from North Berkner Island to the South Pole, skiing 1381 km in 2020, and the male solo record set by British Army officer Henry Worsley, who skied from the south end of Berkner Island toward the Ross Ice Shelf, covering 1459 km. However, Worsley had to be evacuated due to medical issues and subsequently died of organ failure in Puntas Arenas, Chile, in 2016. The longest overall solo skiing journey to date was completed by Norwegian Aleksander Gamme, covering 2260 km in 2012; however, in contrast to the previous described journeys, this was not a one-way journey but included a return journey from Hercules Inlet to the South Pole. ⁷

More recently, scientific studies have focused on understanding the rates of energy expenditure and substrate utilization and body composition, mitigating low energy availability and maintaining performance.^4,8 However, medical issues can impact performance and the success of an expedition. Therefore, the aim of this study was to provide an account of medical issues during the longest solo unsupported one-way polar ski expedition across Antarctica, providing unique insights into such an extreme challenge to the human body.

Case Report

This is a prospective case study of a healthy 33-year-old female. The participant was informed of the study protocol prior to the first test and provided written informed consent. The Internal Review Board of the Charité University Berlin approved all procedures (Approval No. EA1/206/22). The expedition started at Hercules Inlet in November 2022, passing the South Pole toward the inner coast of the Ross Ice Shelf via the Reedy Glacier, where it finished in January 2023. The expedition lasted 70 days and 16 h and covered in total 1484.53 km, the longest solo unsupported one-way polar ski journey in Antarctica. Estimated temperatures ranged from −12 to −50°C (with wind chill), and wind speeds reached 60 mi/h. Compared with a previous and a subsequent Antarctic expedition, the adventurer subjectively described the ambient conditions as challenging, with overall poor visibility, windy conditions, and soft snow, which made the travel across Antarctica generally slower and more demanding than expected. All equipment and nutrition for the expedition were pulled in a 120-kg pulk (sled) by the adventurer. Training for the expedition included a previous expedition to the South Pole (first woman of color to complete a solo ski expedition to the South Pole in 2022), providing invaluable experience. ⁶ The adventurer further trained 6 times per week, including gym work, aerobic work, and dragging 2 tires during approximately 4 h twice weekly to simulate pulling of the pulk.

Pretesting took place at the Center for Space Medicine and Extreme Environments in Berlin. An incremental exercise test was performed on a motorized treadmill (Pulsar 3p, h/p/cosmos, Traunstein, Germany) with continuous breath-by-breath measurements for ventilatory parameters (Metalyzer 3B, Cortex Biophysik, Leipzig, Germany) until task failure. V(dot)O_{2 max} was measured at 49 mL·kg⁻¹·min⁻¹. Basal metabolic rate was 1402 kcal/d (66% carbohydrates, 19% fat, 15% protein; Metalyzer 3B, Cortex Biophysik, Leipzig, Germany). Planned postexpedition testing of ventilatory parameters, V(dot)O_{2 max}, and basal metabolic rate could not be performed due to medical issues.

Anthropometric measurements included pre-expedition height of 175 cm and body mass of 75 kg (body mass index 24.49 kg·m^–2) reducing to 55 kg after the expedition (body mass index 17.96 kg·m^–2), constituting a body mass loss of 20 kg, or 26.7%. Venous blood samples were obtained before and after the expedition (including a full blood count, electrolytes, renal and liver profiles, thyroid function, and glucose and vitamin D concentrations). Pre-expedition vitamin D values showed suboptimal concentrations and were substituted with 2000 IU vitamin D daily prior to the expedition. A wellness questionnaire was used before and after and approximately every 10 d during the expedition to assess general muscle soreness, fatigue, and sleep ⁹ (Table 1).

Table 1.

Results of the wellness questionnaire at various expedition days and before and after the expedition.

Wellness questionnaire	PRE	ED 11	ED 21	ED 31	ED 41	ED 51	ED 61	ED 69	POST
Sleep	5	4	3	2	2	2	2	1	5
Muscle soreness	4	4	3	2	2	2	2	1	3
Fatigue	4	4	3	2	2	2	2	1	3

PRE, before the expedition; ED, expedition day; POST, after the expedition.

Scores range from 1 to 7 on a Likert scale, with 1=very, very poor; 2=very poor; 3=poor; 4=neutral; 5=good; 6=very good; and 7=very, very good.

Medical issues were reported by the adventurer via daily updates and were reviewed in a post-expedition interview. They included musculoskeletal neck pain and a cold injury to the calf. Neck pain started approximately 5 days into the expedition and remained bothersome throughout the expedition, worsening toward the end. The cold injury to the left calf (also called polar thigh ¹⁰ ) started as a small bruise on the upper calf approximately 3 weeks into the expedition and gradually got darker and started scabbing over (Figure 1). This developed through 4 layers of clothing, including loose-fitting Merino wool–based layers (Brynje USA, Donnely, ID), windproof layers, and a polar skirt covering and protecting the thighs to the knees, and ski boots covering the calves. However, the area between the ski boots and the polar skirt (upper calf) may have been an area that was potentially more vulnerable to the persisting winds, which continuously hit the adventurer from behind. The adventurer wore a face mask and goggles to protect the face. No skin was exposed to the cold environment. On days that felt particularly cold, the adventurer wore a full-face mask and on less cold days a half-face mask with goggles and occasionally sunglasses. No cold injuries were reported in any other body parts. The adventurer dressed the calf area daily in the tent, but toward the middle of the expedition the scab broke open, and the skin developed an ulcerated area of approximately 4×6 cm and gradually became more painful. The ulcerated area then was dressed with a Granuflex dressing (ConvaTec, Reading UK), which was left in situ until the end of the expedition (Figure 2). Naproxen (500 mg), paracetamol (1 g), and on occasion codeine (30 mg) were used every other day for pain relief, but due to limited amounts of analgesia, consumption had to be rationed. On arrival at the South Pole (expedition day 56), 1 codeine tablet remained, which was consumed 48 h before the expedition's end. A complete list of medications and dressings taken on the expedition can be seen in Table 2. The adventurer took the same contents of this medical kit to previous and subsequent expeditions to the South Pole, and the authors therefore recommend this list for future expeditions. However, adventurers should consider their own individual circumstances and medical needs, and some of the items, dosages, and quantities may need to be adapted individually. On return to her home country, the adventurer’s injury to the calf was reviewed by plastic surgeons, who performed skin grafting of the area 3 wk after the expedition (Figure 3). The adventurer made an uneventful and complete recovery with only mild self-reported hypersensitivity to light touch in the calf 8 months after the procedure.

Figure 1.

Polar thigh. (a) Initial presentation, looking like a small bruise. (b) Starting to scab over. (c) Weepy and small ulcerated areas that were dressed daily and ultimately covered with a Granuflex dressing. Pictures taken during the expedition in the tent.

Figure 2.

Polar thigh. Post-expedition photo of thigh after removal of Granuflex dressing.

Figure 3.

Polar thigh. (a-c) Post-expedition pictures after skin grafting in different stages of healing.

Table 2.

List of medications and dressings taken on the expedition.

Paracetamol 1 g: 40 tablets

Naproxen 500 mg: 28 tablets

Codeine 30 mg: 28 tablets

Amoxicillin/clavulanate 500/125 mg: 21 tablets

Flucloxacillin 500 mg: 28 tablets

Ciprofloxacin 500 mg: 14 tablets

Omeprazole 20 mg: 14 tablets

Tephine (buprenorphine hydrochloride) 200 microgram: 10 tablets

Clotrimazole 1% cream

Betamethasone dipropionate cream 0.05%

Granuflex hydrocolloid dressing ×4

Zinc oxide tape ×1

Plasters (assorted)

Blister patch ×5

Paraffin gauze dressing (Jelonet)

K-Tape ×2

Discussion

Our aim was to provide data on medical issues during the longest solo unsupported one-way polar ski expedition across Antarctica. The main findings were (1) cold injury to the calf (polar thigh), (2) overuse injury to the neck musculature and general muscle soreness and fatigue, (3) important body mass loss over the duration of the expedition, and (4) relatively stable blood parameters before and after the expedition.

Polar Thigh

The injury to the leg has been described previously by some Antarctic travelers, has attracted some attention on social media and by the lay press, and has been termed polar thigh. ¹⁰ Although the thigh is most commonly affected, the calf has been described as an anatomic area of injury as well. ¹⁰ However, to our knowledge, this particular clinical presentation has not been reported previously in the scientific literature, and little is known about its pathophysiology, risk factors, or treatment.

Cold injuries can be classified as freezing and nonfreezing cold injuries (NFCIs). ¹¹ While freezing cold injuries generally require temperatures of <0°C, resulting in frostbite from direct tissue freezing and leading to cellular ice crystal formation with cellular dehydration and microvascular occlusion during rewarming, ¹¹ NFCIs generally occur with prolonged exposure to near-freezing temperatures, resulting in alternating periods of vasoconstriction and vasodilation in the affected tissues, as has been commonly observed in the foot (eg, trench foot), which occurs in wet, cold conditions. Chilblains as a localized NFCI can present 12 to 24 h after initial cold exposure, especially on the face, hands, feet, thighs, and shins as an inflammatory vascular response, with pruritic skin discoloration, edema, purple papules, macules, plaques, or nodules and/or blistering that typically self-resolves. However, chronic exposure to cold can result in chronic chilblains and further damage to the affected area. ¹¹ We believe that the underlying pathophysiologic mechanism of polar thigh most likely resembles that of an NFCI, but further investigation is recommended.

Anecdotally, polar thigh has been observed more commonly in female Antarctic adventurers, in colder and windier environmental conditions, particularly in the Antarctic compared with other cold environments (eg, Greenland or Alaska), and when skiing in windy conditions. ¹⁰ A potential link with Merino wool is suggested, which is less breathable than synthetic clothing material, resulting in less ventilation, moister, and more irritated skin, potentially leading to local cold injury and infection. ¹⁰ The adventurer did not report of any tight-fitting clothing or skin irritation or notable moister accumulation, but due to the intense workload while skiing and pulling the heavy pulk during the initial stage of the expedition, some perspiration may have occurred.

No epidemiologic data are available on cold injuries on Antarctic expeditions, but frostbite often occurs on exposed areas and/or extremities such as the face, feet, and hands. ² A retrospective analysis of cold injuries of members of the British Antarctic Survey in Antarctica showed that cold injuries were uncommon in this population, with an incidence of 65.6 per 1000 per year. Most were superficial frostbite to the face, but the majority of these injuries occurred during recreation activities such as skiing, which makes people on prolonged skiing expeditions likely more susceptible to cold injuries. ¹² Preventative strategies include appropriate equipment and clothing; protecting the skin from moisture, wind, and cold; avoiding perspiration or wet extremities; and avoiding the same position for prolonged periods of time.^13,14

Field classification of cold injuries follow a 2-tiered classification scheme with superficial or minimal anticipated tissue loss corresponding to first- and second-degree injury and deep anticipated tissue loss corresponding to third- and fourth-degree injury. ¹⁴ Treatment depends on the extent of the injury and may include thrombolytic agents if administered in the early stages. Regardless of treatment, meticulous wound care with delayed debridement is critical. ¹⁵ This is the treatment followed by the adventurer, with delayed debridement and skin grafting.

Neck Pain and General Fatigue

The musculoskeletal neck pain developed as an overuse injury early during the expedition caused by pulling the heavy pulk during poor visibility and stormy weather and soft snow while continually looking down (flexed neck position) at a compass for direction. The neck musculature (particularly the sternocleidomastoids) remained painful throughout the expedition, and analgesia from the medical kit (see Table 2) was used, including paracetamol, naproxen, and codeine, either as monotherapy or in combination, which provided effective subjective temporary relief. General feelings of fatigue, muscle soreness, and deterioration of sleep were observed, as demonstrated by the wellness score, with very poor results at end of the expedition. This is hardly surprising considering the extreme demands of such an expedition, and similar findings have been described previously by solo adventurers.^4,16

Body Mass Changes

Our adventurer experienced an important body mass loss of approximately 20 kg (26.7%) over the duration of the expedition while consuming approximately 5000 kcal daily. Nutritional advice was given from an outside agency and not the research team involved in this study. However, similar body mass losses of about 20 kg after a 96-d expedition have been observed in other solo adventurers despite consuming 5000 kcal·d^–1 on average. ⁴ Previous studies estimated that energy intake varied between a mean daily amount of approximately 6500 kcal·d^–1 for male adventurers traversing Antarctica and around 5000 kcal·d^–1 for female adventurers.^8,17 The primary impact of the low temperatures in Antarctica is to increase the basal metabolic rate to maintain core temperature. ¹⁷ Nevertheless, considerable body mass loss during strenuous activities should be avoided, and expert nutritional advice can help prevent this as well as future research into optimal nutrition for such expeditions.

Blood Changes

It is well known that acute and chronic prolonged ultraendurance activities can have an effect on the hematologic, biochemical, and immune system, which can be reflected in changes in blood parameters from before to after exercise. ¹⁸ However, due to the injury of the adventurer, the original research protocol had to be altered, and immediate post-expedition blood sampling at the research facility had to be postponed until 10 days after the expedition, therefore likely affecting the result, because it did not show any abnormalities (apart from mildly elevated serum urea and serum alanine aminotransferase levels). However, results indicate rapid recovery following such an extreme endeavor.

Conclusion

This study provides novel medical data of the longest solo unsupported one-way polar ski expedition across Antarctica. For the first time, polar thigh, a cold injury to the calf, is described in the scientific literature. The likely underlying pathophysiologic mechanism is that of a localized nonfreezing cold injury potentially linked to continuous cold exposure, windy conditions, and clothing material. The adventurer also developed a debilitating overuse musculoskeletal neck injury due to environmental and equipment issues as well as general fatigue and reduction in sleep. Important changes in body mass are also reported, with an approximate loss of 20 kg (26.7%). This case study contributes to the body of knowledge and may inform strategies for future expeditions in extreme environments. Further research into the incidence, pathophysiology, treatment, and risk factors of polar thigh is recommended.