Letter to the Editor

Ann Lab Med 2020; 40(1): 92-94

Published online January 1, 2020

Copyright © Korean Society for Laboratory Medicine.

Laboratory Investigation of the 900-km Lapland Extreme Challenge

Elisabetta Stenner, B.Sc.1 , Luca Giovannella, M.D., Ph.D.2 , Giorgia Raffaelli, M.D.3 , Giorgio Delbello, M.D.4 , Maurizio Ruscio, M.D.1 , and Roberto Verna, M.D., Ph.D.5,6

1SC Laboratorio Unico di ASUITs, Burlo, Gorizia e Monfalcone, Dipartimento di Medicina dei Servizi, Azienda Sanitaria Universitaria di Trieste, Trieste, Italy; 2Centro Malattie Tiroidee, Clinica di Medicina Nucleare e Imaging Molecolare, Istituto di Imaging della Svizzera Italiana, Bellinzona, Switzerland; 3U.O.C. Medicina Trasfusionale e Patologia Clinica, Repubblica di San Marino – Istituto per la Sicurezza Sociale, San Marino, Republic of San Marino; 4Dipartimento di Scienze Mediche Chirurgiche e della Salute, Università degli Studi di Trieste, Trieste, Italy; 5World Association of Societies of Pathology and Laboratory Medicine, Milan, Italy; 6Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy

Correspondence to: Roberto Verna, M.D., Ph.D.
Department of Experimental Medicine, Sapienza University of Rome, Viale Regina Elena 324, Rome 00161, Italy
Tel: +393711547775 E-mail:

Received: April 21, 2019; Revised: June 25, 2019; Accepted: August 7, 2019

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Dear Editor,

The Lapland Extreme Challenge (LEC) is a 900 km ultra-event through the Finnish Lapland wilderness. It was created in 2013; the time limit of the event is 30 days, but 2017 was the only year, in which this ultra-event had finishers. The athletes need to transport with them everything necessary to survive. As an outstanding stress model, it includes strenuous exercise, freezing temperatures, sleep restriction, and isolation/solitude, and all of them present simultaneously [1].

This study aimed to monitor biochemical parameters (BP) from the training (October 2016) through the restoring period (June 2017). However, owing to the high skill level required to perform the LEC, only one athlete (age: 51 years, sex: male, height: 177 cm) was monitored. During the race, he travelled 30–40 km in 10–12 hours a day, dragging a sled of about 50 kg, using skis for one half and snow boots for the other. He slept around five hrs a day, mostly in a tent. He ate mostly lyophilized food for a total of 3,800–4,200 kcal/day (about 25% carbohydrate, 65% fat, and 10% protein) and drank about 2.5 L/day of liquefied snow with mineral salt added. The environmental temperatures ranged from −15℃ to −36℃. On the tenth day, after 450 km, he gave up due to frostbite (in his right thumb and part of the left foot, no permanent damage). BP were obtained at the following time points: 7:30 am, before the beginning of the training (T1: October 2016), each month before the LEC (T2: November 2016, T3: December 2016, T4: January 2017), immediately before and after the LEC (T5: February 2017, T6: March 2017), and each month after the LEC (T7: April 2017, T8: May 2017, T9: June 2017). Blood samples were centrifuged within two hours (in a hospital/on field); four aliquots of each blood sample drawn were frozen (two at −80℃ and two at −20℃) for five days, after which all parameters were measured. In this way, all blood samples were analyzed at the same time, thereby reducing pre-analytical variability. Inter-sample differences bigger than the critical reference change value (RCV) were considered significant [2]. RCV was calculated as follows:


where Z=1.96 for 95% significance, CVa is the analytical variation and CVw is the coefficient of variation for intra-individual biological variation.

This study was performed according to the Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans; the athlete provided informed consent.

The results are summarized in Table 1. Cortisol, bone alkaline phosphatase, and osteocalcin trends are shown in Fig. 1. The weight and body fat percentage of the athlete were 84 kg and 14.3% at T1, 70 kg and 11% at T6, and 82 kg and 15% at T9, respectively.

The increased creatine kinase values suggested muscle damage due to the high training workout. This was observed especially during the competition when creatine kinase, lactate dehydrogenase, and myoglobin significantly peaked [3]. However, frostbite to the right thumb and part of the left foot could have contributed to the increased biomarker values. Creatinine shows changes within the RCV for subjects undergoing regular aerobic training [4]. Moreover, cystatin-C and neutrophil gelatinase-associated lipocalin remained basically unchanged, suggesting the absence of any exercise-associated renal impairment [5]. The significant increase in potassium observed after the LEC (T6) was at least in part due to the possible exercise-induced metabolic acidosis, which promotes extracellular accumulation of K+ (controlled by KATP channels) [6]. Sodium, phosphorus, and magnesium values were basically unchanged, suggesting electrolyte homeostasis.

The decrease in bone formation biomarker values (bone alkaline phosphatase and osteocalcin) after the LEC (T6) indicated a temporary suppression of bone formation, partly due to the exercise associated with the severe energy deficit that leads to a notable reduction (−12.5%) in total body weight after LEC [7].

Cortisol values remained within the reference range except after the LEC (T6), when they dropped significantly. This was in part unexpected considering that long duration exercise, sleep deprivation, and extreme conditions seem to increase the pituitary-adrenal cortex response [8]. However, another study regarding cortisol responses to extreme sports highlighted a significant drop during the performance, ending with values below the basal value [9]. A possible explanation could be that for these elite athletes, including the one we monitored, the extreme challenge is essential for their psychological well-being [10]. Consequently, it could be associated with less cortisol secretion, independently of the intense load and risk associated with severe environmental conditions.

In conclusion, apart from frostbite, this athlete seemed to respond physiologically to an extreme exercise load despite the transient decrease in bone formation biomarker values. It suggests that precaution should be taken in constant ultra-endurance training and frequent ultra-endurance competitions.

Conflicts of Interest: None declared.
The authors thank Dr. Nicholas Carter for proofreading this article.
Fig. 1.

Changes in biochemical parameters during the four-month training period (T1–T5), immediately after the Lapland Extreme Challenge (T6), and a few months after the Lapland Extreme Challenge (T7–T9): (A) Cortisol, (B) bone alkaline phosphatase, and (C) osteocalcin.

Biochemical parameters during the four-month training period (T1–T5), immediately after the Lapland Extreme Challenge (T6), and a few months after the Lapland Extreme Challenge (T7–T9)

AnalyteReference rangeRCV (%)T1–T5 mean ± SD (CV%)T6T7–T9 mean ± SD (CV%)
Creatine kinase (µKat/L)*0.42–3.31396.66 ± 5.49 (82)12.395.25 ± 2.23 (42)
Lactate dehydrogenase (µKat/L)*< 4.17233.40 ± 1.12 (33)4.272.95 ± 0.13 (5)
Myoglobin (nmol/L)< 4.00431.66 ± 0.17 (12)2.401.83 ± 0.34 (18)
Sodium (mmol/L)*135–1455140 ± 1 (0.8)140140 ± 1 (0.7)
Potassium (mmol/L)*3.50–5.1084.63 ± 0.49 (11)5.574.5 ± 0.5 (11)
Phosphorus (mmol/L)*0.81–1.45151.16 ± 0.07 (6)1.161.13 ± 0.01 (0.3)
Calcium (mmol/L)*2.12–2.6252.31 ± 0.11 (5)2.212.31 ± 0.13 (6)
Magnesium (mmol/L)*0.73–1.0580.82 ± 0.02 (2)0.900.86 ± 0.03 (4)
Enzymatic creatinine (µmol/L)*44–1151286 ± 2 (3)10391 ± 4 (5)
Cystatin C (mg/L)0.20–0.62NA0.25 ± 0.02 (7)0.250.27 ± 0.03 (10)
Neutrophil gelatinase-associated lipocalin (µg/L)≤ 60NA20 ± 0 (0)2020 ± 10 (34)
Bone alkaline phosphatase (µg/L)3.70–21.00209.92 ± 0.96 (10)7.110.30 ± 0.15 (1.5)
Carboxy-terminal collagen crosslinks (ng/L)§120–75030530 ± 60 (11)390470 ± 30 (6)
25-hydroxy-vitamin D (nmol/L)75–125NA82 ± 5 (6)7867 ± 12 (20)
Osteocalcin (µg/L)4.60–65.403117.20 ± 1.90 (11)9.217.10 ± 1.40 (8)
Parathyroid hormone (ng/L)11–885536 ± 10 (29)3251 ± 22 (42)
Cortisol (nmol/L)185–62431417 ± 77 (18)178452 ± 97 (21)

  1. Lucas SJ, Helge JW, Schütz UHW, Goldman RF, Cotter JD. Moving in extreme environments: extreme loading; carriage versus distance. Extrem Physiol Med 2016;5:6.
  2. Walz B, Fierz W. The concept of reference change values (RCV). Will it supersede reference intervals?. Ther Umsch 2015;72:130-135.
  3. Rawson ES, Clarkson PM, Tarnopolsky MA. Perspectives on exertional rhabdomyolysis. Sports Med 2017;47:S33-S49.
  4. Nunes LA, Brenzikofer R, de Macedo DV. Reference change values of blood analytes from physically active subjects. Eur J Appl Physiol 2010;110:191-198.
  5. Hewing B, Schattke S, Spethmann S, Sanad W, Schroeckh S, Schimke I, et al. Cardiac and renal function in a large cohort of amateur marathon runners. Cardiovasc Ultrasound 2015;13:13.
  6. Sumi D, Kojima C, Kasai N, Goto K. The effects of endurance exercise in hypoxia on acid-base balance and potassium kinetics: a randomized crossover design in male endurance athletes. Sports Med Open 2018;4:45.
  7. Zanker CL, Cooke CB. Energy balance, bone turnover, and skeletal health in physically active individuals. Med Sci Sports Exerc 2004;36:1372-1381.
  8. Vaananen I, Vasankari T, Mäntysaari M, Vihko V. Hormonal responses to 100 km cross-country skiing during 2 days. J Sports Med Phys Fitness 2004;44:309-314.
  9. Stenner E, Gianoli E, Piccinini C, Biasioli B, Bussani A, Delbello G. Hormonal responses to a long duration exploration in a cave of 700 m depth. Eur J Appl Physiol 2007;100:71-78.
  10. Clough P, Houge Mackenzie S, Mallabon L, Brymer E. Adventurous physical activity environments: a mainstream intervention for mental health. Sports Med 2016;46:963-968.