Study of Injury and
Illness Rates in Multiday Ultramarathon Runners

BJ, Waite B. & Schiff MA. Medicine and Science in Sports and Exercise. 2011;
43: 2314-2320.

races occur over the course of a couple of days, carrying gear/supplies, are up
to 150 miles, and may include running extreme terrains.  Few studies have evaluated injuries among
multiday ultramarathon runners.  Therefore,
the purpose of this study was to evaluate injury/illness rates in a group of
off-road ultramarthon runners during several similar races.  This particular series of 4 races were over 7
days across extreme terrain (e.g., dessert, wilderness), and participants were primarily
experienced ultraendurance runners. 
Medical checkpoints were staffed by physicians along the course and any
injury/illness was documented if a runner encountered the medical staff.  Encounters were classified as minor or major
in the following 3 categories: medical illness (e.g., hyperthermia, collapse,
hyponatremia, cardiac), musculoskeletal injury, or skin disorder.  Four hundred and seven runners completed the
races, and 396 (97%) participated in the study and were predominately male
(79%).  Over the course of 4 races, 85%
of runners were evaluated by medical staff and 15% required no medical
care.  Almost 95% of all encounters were
minor in nature.  Of these minor injuries
74% were skin related, 18% musculoskeletal, and 8% other medical illnesses.  Only 5% of the injuries were considered
major, and this was mostly medical illnesses (e.g., hyponatremia, asthma,
hematuria; 58% of all major injuries). 
An increase in age was associated with a lower injury/illness rate and
females had higher rates of illnesses than males. 

difficult terrain, significant distances, and extreme weather conditions,
injuries/illnesses that occur during these races are largely minor and
frequently involve skin-related disorders of the foot.  This does not seem surprising.  Musculoskeletal injury rates (0.71 per
runner) within this study were relatively lower than pervious findings on
ultramarathoners.  What is also
interesting is that injury rates in the population were significantly lower
than rates previously found among marathoners. 
Marathoners often include experienced as well as some less experienced
runners.  In contrast, ultramarthoners consist
primarily of experienced runners who have trained for these extreme conditions.  It would appear that conditioning,
acclimatization, and physical strength may have influence on injury at this
level.  Females have a higher incidence
of illnesses, which may be attributed to the larger relative size of the 7 days
worth of supplies that they must carry throughout the race.  What was also interesting is that this study
stated that all participants were offered the same amount of water for any
given day.  It would be interesting to
see how much water was consumed by participants.  Females are susceptible to hyponatremia,
therefore water consumption may influence the incidence of medical
illnesses.  Runner education or
monitoring of sweat rates may be critical to the understanding of these medical
illnesses.  Also, most medical encounters
happened early in the race.  This may
have to do with acclimatization issues as well as travel (e.g., jet lag)
issues.  Clinically, we may not encounter
many athletes that are at this level, but it is very interesting and may have
carryover to marathons and other running populations.  It appears that experienced runners have few
injury or illness issues, and that we may need to target the less experienced
runners.  A research study investigating
marathon runners may help to see if experience level is protective within this
population, as it appears to be in the ultramarathoners.  Does anyone have any experience with events
like this, either as runners themselves or athletes that they have

by: Nicole Cattano
by: Jeffrey Driban


Krabak BJ, Waite B, & Schiff MA (2011). Study of injury and illness rates in multiday ultramarathon runners. Medicine and Science in Sports and Exercise, 43 (12), 2314-20 PMID: 21552155