EDITORIAL
Open Access
Born to run. Studying the limits of human
performance
Andrew Murray1* and Ricardo JS Costa2
Abstract
It is recognised that regular physical activity and a high level of fitness are powerful predictors of positive health
outcomes. There is a long and rich history of significant feats of human endurance with some, for example, the
death of the first marathon runner, Pheidippides, associated with negative health outcomes.
Early studies on endurance running used X-ray and interview techniques to evaluate competitors and comment on
performance. Since then, comparatively few studies have looked at runners competing in distances longer than a
marathon. Those that have, tend to show significant musculoskeletal injuries and a remarkable level of adaptation
to this endurance load.
The TransEurope Footrace Project followed ultra-endurance runners aiming to complete 4,500 Km of running in 64
days across Europe. This pioneering study will assess the impact of extreme endurance on human physiology;
analysing musculoskeletal and other tissue/organ injuries, and the body’s potential ability to adapt to extreme
physiological stress. The results will be of interest not only to endurance runners, but to anyone interested in the
limits of human performance.
Please see related article: http://www.biomedcentral.com/1741-7015/10/78
Keywords: Physical inactivity, ultra-marathon, endurance, runners, musculoskeletal, nutrition, hydration, race, Trans-
Continental
Background
Professor Steven Blair describes physical inactivity as “one
of the most important public health challenges of the 21st
Century” [1]. It is recognized that regular physical activity
and a high level of fitness are powerful predictors of posi-
tive health outcomes, with Professor Karim Khan, who is a
prominent sports and exercise medicine researcher, fram-
ing Blair’s data, to show that low fitness may be responsi-
ble for a larger attributable fraction of mortality than
“Smokadiabesity"- that is smoking, diabetes, and obesity
combined [2].
Can there ever be too much of a good thing? Can we
ever do too much physical activity? History suggests the
human body is perfectly adapted to run long distances.
Humans have an unmatched ability in the animal king-
dom to run these distances, capabilities that probably
emerged around 2 million years ago to assist with
persistence hunting - a tactic still used by the San Bush-
men of the Kalahari [3].
History celebrates the run in 490 BC from Marathon to
Athens by Pheidippides as the inspiration for the modern
marathon, whilst remembering that this hero of ancient
Greece died following his exertions. The traditional story
tells that Pheidippides had, in fact, run from Athens to
Sparta, a distance of 240 km in less than 48 hours shortly
before. This would be defined as an ultra-marathon,
which is considered any distance in excess of the stan-
dard marathon distance of 42.195 km. Of interest are the
physiological changes that accompany such extreme chal-
lenges. In a study published in BMC Medicine, Schutz
et al. [4] followed 44 ultra-marathon runners in the
TransEurope Footrace 2009, which is a distance of over
4,487 km from South Italy to North Cape. Here, they
recorded daily sets of data from magnetic resonance ima-
ging, psychometric, body composition and biological
measurements with the aim of uncovering new knowl-
edge on the physiological and pathological changes that
* Correspondence: docandrewmurray@googlemail.com
1SportScotland Institute of Sport, Aithrey Road, Stirling, FK9 5PH, UK
Full list of author information is available at the end of the article
Murray and Costa BMC Medicine 2012, 10:76
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© 2012 Murray and Costa; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
accompany cellular and organ systems under extreme
strain.
Previous studies: What is known about ultra-endurance
running?
Humans have been racing across continents since the
1928 and 1929 U.S. Trans-Continental Races. In his
seminal work “Lore of Running” Tim Noakes notes that
2 separate medical reports were compiled from the
4,960 km, 84 stage 1928 race. J.T. Farrell et al. con-
cludes “the immediate effects of long-distance running
are inconsequential” from his team’s X-ray studies of
the heart, bones and joints; while Gordon and Baker
concluded only 40 of the 199 competitors were capable
of sustaining this physical workload [5]. Musculoskeletal
injuries and financial difficulties were cited as principal
reasons that only 55 of the 199 competitors finished [5].
Since these early studies, little research has been con-
ducted on extreme endurance runners. Numerous studies
have looked at musculoskeletal injuries in marathon run-
ners, but few exist of athletes running further than this.
Fallon studied musculoskeletal injuries in athletes run-
ning 1,005 km from Sydney to Melbourne finding injuries
to the knee, and ankle to be most prevalent [6]; while
Scheer and Murray amongst others also found lower
limb musculoskeletal injuries to be common [7]. Fallon
also described an injury fairly specific to ultra-endurance
runners, tendinopathy of the ankle dorsiflexors, a condi-
tion subsequently called “Ultra-marathoner’s ankle” [6].
Other studies have looked at immune status, nutrition,
and hydration in ultra-endurance runners. Perturbed
immune function is a common feature after endurance
type exercise, with clinical significance associated with
increased risk of illness, infection, suppressed tissue
repair and wound healing abilities, and exertional heat ill-
nesses [8]. Consuming adequate nutrition to meet nutri-
ent demands and maintaining euhydration has shown to
attenuate some of the immune perturbing effects of
extreme endurance running [9,10]; this not only has
immune and health consequences, but will affect running
performance on consecutive days of competition [11].
A perceived common outcome of running exercise in
the heat is dehydration, and thus much focus has pre-
viously been on promoting hyperhydration strategies dur-
ing ultra-endurance events. Evidence from previous
reviews and preliminary data from Coventry University
actually suggests that fluid-overconsumption behaviours
are a common feature of ultra-endurance running, with
large ingestions of plain water and insufficient sodium
replacement frequently observed [12]. This type of drink-
ing behaviour is associated with the manifestation of hypo-
natraemia, which recently has had much interest, with
cases of asymptomatic and symptomatic hyponatraemia
becoming better recognised during ultra-endurance events
[13].
O’Keefe et al. recently found prolonged endurance
exercise may cause pathologic remodelling of the heart
and be pro-arrythmogenic with atrial fibrillation as much
as five times more prevalent in the population studied
[14]. Moreover, interesting case studies exist. In his book
“Survival of the Fittest” Dr Mike Stroud described the
destruction of the human body when studying the effects
of a brutal 95 day Antarctic crossing, at times burning
>10,000 kcal·day-1 [15]. Unpublished blood values from
Andrew Murray’s ultra-endurance run from Scotland to
the Sahara desert showed a drop in haemoglobin to
10.8 g·dl-1, and a serum ferritin of 2 ng·ml-1, from pre-
viously normal values, despite a dietary iron intake 450%
of recommended nutritional intake (RNI), and body
weight being maintained.
What this study adds: assessing the impact of extreme
endurance on human physiology
The TransEurope Footrace Project followed 44 ultra-
endurance runners aiming to complete 4,500 km of run-
ning in 64 days across Europe. Comfortably the largest
and most comprehensive of its kind to date, it aimed at
demonstrating the feasibility of conducting a longitudinal
study over this period collecting a large and wide ranging
amount of data which included: 741 magnetic resonance
imaging (MRI) examinations, 5,720 urine samples, 244
blood samples, 205 electrocardiogram examinations,
1,018 bioelectrical impedance analysis measurements,
539 anthropological measurements, and 150 psychologi-
cal questionnaires. This pioneering study will assess the
impact of extreme endurance on human physiology; ana-
lysing musculoskeletal and other tissue/organ injuries,
and the body’s potential ability to adapt to extreme phy-
siological stress.
Although running is one of the most popular forms of
recreation worldwide, not many will wish to gallop across
continents. But ultra-endurance running is increasing
dramatically in popularity and this study will be of inter-
est to anyone with an interest in the limits of human per-
formance, and the ability of man to adapt to seemingly
impossible challenges. Comparisons with athletes under-
taking feats of endurance including cycling’s Tour de
France will be interesting.
Conclusions
There is a long and rich history of significant feats of
human endurance. Remarkably, studies have been con-
ducted on trans-continental races since 1928. Similarities
between these early studies and the TransEurope Foo-
trace Project include the distance covered, and the use of
imaging. However, advances in technology has meant
Murray and Costa BMC Medicine 2012, 10:76
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that the TransEurope Footrace Project has been able to
acquire longitudinal data from a relatively large volunteer
cohort of ultra-marathon runners including data on mus-
culoskeletal, cardiac, and brain MRI, along with a raft of
other data on immune function, hydration and nutrition.
Data is likely to show that competing in such an event
can lead to significant musculoskeletal and other inju-
ries, but also that the human body is capable of adapting
to incredible endurance loads, and can run well in
excess of a marathon per day despite seemingly signifi-
cant medical issues. Like the runners, research in this
field will continue to move forward.
Author details
1SportScotland Institute of Sport, Aithrey Road, Stirling, FK9 5PH, UK.
2Department of Health Professions, Coventry University, Priory Road,
Coventry, CV1 5FB, UK.
Authors’ information
AM and RC have completed over 100 ultra-marathons between them. AM
completed a run across Europe in 2011 and is a Sports and Exercise
Medicine doctor. He has worked at numerous ultra-marathon events with
Marathon Medical Services. RC is a former professional triathlete and is
currently a Senior Lecturer and Researcher Fellow in Dietetics and Human
Nutrition at Coventry University. AM and RC have both produced original
research from ultra-marathon competition.
Received: 13 July 2012 Accepted: 19 July 2012 Published: 19 July 2012
References
1.
Blair SN: Physical inactivity: The biggest public health problem of the
21st Century. Br J Sports Med 2009, 43:1-2.
2.
Khan KM, Tunaiji HA: As different as Venus from Mars: time to distinguish
efficacy (can it work?) from effectiveness (does it work?). Br J Sports Med
2011, 45:759-760.
3.
Lieberman DE, Bramble DM: The evolution of marathon running:
capabilities in humans. Sports Med 2007, 37:288-90.
4.
Schulz , et al:, (to be added when published).
5.
Noakes T: From Learning from the experts in Lore of Running.Edited by:
Noakes T. Oxford: Oxford University Press; 2001:361-483.
6.
Fallon KE: Musculoskeletal injuries in the ultra-marathon: the 1990
Westfield Sydney to Melbourne run. Br J Sports Med 1996, 30:319-323.
7.
Scheer BV, Murray AD: Al Andalus Ultra Trail: An Observation of Medical
Interventions During a 219-km, 5-Day Ultramarathon stage race. Clin J
Sports Med 2011, 21:444-446.
8.
Walsh NP, Gleeson M, Shephard RJ, Gleeson M, Woods JA, Bishop NC,
Fleshner M, Green C, Pedersen BK, Hoffman-Goetz L, Rogers CJ, Northoff H,
Abbasi A, Simon P: Position statement. Part one: Immune function and
exercise. Exerc Immunol Rev 2011, 17:6-63.
9.
Walsh NP, Gleeson M, Pyne DB, Nieman DC, Dhabhar FS, Shephard RJ,
Oliver SJ, Bermon S, Kajeniene A: Position statement. Part two:
Maintaining immune health. Exerc Immunol Rev 2011, 17:64-103.
10.
Costa RJS, Walters R, Bilzon JLJ, Walsh NP: Effects of immediate
postexercise carbohydrate ingestion with and without protein on
neutrophil degranulation. Int J Sport Nutr Exerc Metab 2011, 21(3):205-213.
11.
American College of Sports Medicine, American Dietetic Association,
Dietitians of Canada: American College of Sports Medicine position stand.
Nutrition and athletic performance. Med Sci Sports Exerc 2009,
41(3):709-731.
12.
Hew-Butler T, Ayus JC, Kipps C, Maughan RJ, Mettler S, Meeuwisse WH,
Page AJ, Reid SA, Rehrer NJ, Roberts WO, Rogers IR, Rosner MH, Siegel AJ,
Speedy DB, Stuempfle KJ, Verbalis JG, Weschler LB, Wharam P: Statement
of the Second International Exercise-Associated Hyponatremia
Consensus Development Conference. Clin J Sport Med 2007, 18(2):111-121.
13.
Noakes TD, Sharwood K, Speedy D, Hew T, Reid S, Dugas J, Almond C,
Wharam P, Weschler L: Three independent biological mechanisms cause
exercise-associated hyponatremia: evidence from 2,135 weighed
competitive athletic performances. Proc Natl Acad Sci USA 2005,
102(51):18550-18555.
14.
O’Keefe JH, Patil HR, Lavie CJ: Potential Adverse Cardiovascular Effects
From Excessive Endurance Exercise. Mayo Clinic Proceedings 2012,
87(6):587-595.
15.
Stroud M: Survival of the Fittest.Edited by: Stroud M. London: Yellow
Jersey Press; 2004:.
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Born to run. Studying the limits of human performance.
Murray, Andrew,Costa, Ricardo J S