Prevalence of musculoskeletal disorders among Norwegian female biathlon athletes

Abstract

The purpose was to examine musculoskeletal disorders in Norwegian female biathlon athletes (age ≥ 16), both juniors and seniors. The design was a retrospective cross-sectional study. In all, 148 athletes (79.1%) responded; of these, 118 athletes were 16-21 years (juniors) (77.6%), and 30 athletes were 22 years or older (seniors) (20.3%), and mean age was 19.1. A validated questionnaire was used to collect the data. The prevalence of musculoskeletal disorders was 57.8%. The most affected parts were the knee (23.0% of the total injuries), calf (12.2%), ankle/foot (10.8%), lower back (10.8%), and thigh (10.1%). The disorders resulted in training/competition cessation for 73.5% of athletes, in alternative training for 87.8%. Fifty percent of the athletes had one or several musculoskeletal disorders. Most of the problems occurred preseason, and the duration of symptoms was often prolonged. Few differences between the juniors and seniors were found. This study showed the prevalence of musculoskeletal problems among female biathlon athletes. The results indicate that prevention of lower limb problems must be prioritized, especially during the preseason.

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Open Access Journal of Sports Medicine 2013:4 71–78
Open Access Journal of Sports Medicine
Prevalence of musculoskeletal disorders among
Norwegian female biathlon athletes
Håvard Østerås1
Kirsti Krohn Garnæs2
Liv Berit Augestad3
1Department of Physical Therapy,
Faculty of Health Education and
Social Work, Sør-Trøndelag University
College, Trondheim, Norway;
2Department of Human Movement
Science, Norwegian University of
Science and Technology, Trondheim,
Norway; 3Department of Human
Moveme nt Scie nc e, Norwegian
University of Science and Technology,
Trondheim, Norway
Correspondence: Håvard Østerås
Sør-Trøndelag University College,
Faculty of Health Education and Social
Work, Department of Physical Therapy,
Ranheimsv 10, N-7004 Trondheim,
Norway
Tel +47 73 55 9305
Fax +47 73 55 9351
Email havard.osteras@hist.no
Abstract: The purpose was to examine musculoskeletal disorders in Norwegian female biathlon
athletes (age $ 16), both juniors and seniors. The design was a retrospective cross-sectional
study. In all, 148 athletes (79.1%) responded; of these, 118 athletes were 16–21 years (juniors)
(77.6%), and 30 athletes were 22 years or older (seniors) (20.3%), and mean age was 19.1.
A validated questionnaire was used to collect the data. The prevalence of musculoskeletal
disorders was 57.8%. The most affected parts were the knee (23.0% of the total injuries), calf
(12.2%), ankle/foot (10.8%), lower back (10.8%), and thigh (10.1%). The disorders resulted in
training/competition cessation for 73.5% of athletes, in alternative training for 87.8%. Fifty per-
cent of the athletes had one or several musculoskeletal disorders. Most of the problems occurred
preseason, and the duration of symptoms was often prolonged. Few differences between the
juniors and seniors were found. This study showed the prevalence of musculoskeletal problems
among female biathlon athletes. The results indicate that prevention of lower limb problems
must be prioritized, especially during the preseason.
Keywords: injuries, cross-country skiing, skating
Introduction
Biathlon is an endurance sport which combines cross-country skiing and skating
technique with shooting. This sport requires high training loads and repetitive type of
training through the whole year, and top level performance in biathlon has become
more demanding for both sexes, with significant increases in number of races, and
total and daily amount of training.1 The sport-specific demands may increase the
athlete’s risk for injuries, fatigue, and overuse problems and sets stringent require-
ments for rest and nutrition.
Biathlon has traditionally been a male sport, but in the last 10–15 years, the sport
has experienced a markedly increased number of female athletes, both at the national
and international level. A search for relevant literature revealed a lack of publications
related to health issues in biathlon specifically and a limited number of studies related
to the prevalence of injuries among female endurance athletes generally.2
Several studies among endurance athletes have found a higher prevalence of knee
problems and a higher risk for stress fractures among female athletes compared with
male athletes.3,4 Studies of cross-country skiing in both sexes showed a high prevalence
of problems related to overuse compared with acute injuries,5,6 which is in accordance
with findings in other endurance sports, such as cross-country running, orienteering,
and cycling.3 Studies of both male and female cross-country skiers have also found an
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increased risk for injuries/disorders in the lower extremity
of the body compared with the upper extremity,6 and in the
lower-back region.5,7,8
It is of interest to acquire knowledge regarding injuries and
other musculoskeletal problems related to female biathlon,
to be able to prevent negative health outcomes, to complete
sufficient treatment, and to support high-level performance.
Our hypothesis was that this population of athletes has a high
prevalence of musculoskeletal disorders and that in order
to develop a good preventive intervention program, it was
necessary to know more about this. The aim of this study
was to examine the prevalence of musculoskeletal disorders
among Norwegian female biathlon athletes.
Methods
Design
The design of the study employed a retrospective, cross-
sectional survey that elicited longitudinal data.
Subjects
All Norwegian female biathlon athletes who had paid
the Norwegian Biathlon Federation (NSSF) for license
to compete in the 2007 biathlon season were eligible for
inclusion in this study. Athletes aged 16–21 years comprised
the junior group, and athletes 22 years and older comprised
the senior group; the junior and senior age groups were in
accordance with those employed by the NSSF. Both groups
consisted of athletes at both national and international level
of performance.
Instruments and procedures
A letter was sent to all the athletes who were eligible for
inclusion in this study, a total of 187 athletes; 152 juniors and
35 seniors. The mailing contained a request, a consent letter,
an information letter, a questionnaire, and a stamped envelope
for returning the questionnaire. Reminders were sent by both
email and postal service and contained a new consent letter,
questionnaire, and envelope with postage. The subjects were
identifiable through a number written on the questionnaire,
to enable a follow-up study. A total of 152 athletes (81.3%),
122 juniors (80.3%) and 30 senior (85.7%), athletes agreed
to participate and returned a completed questionnaire. Of
the junior athletes, four were excluded: one because she had
quit biathlon 1 year ago; three because they were incorrectly
registered by the NSSF as junior and were under 16-years-old.
Finally, 148 (79.1%) participated in this study, 118 (77.6%)
junior athletes and 30 (85.7%) senior athletes.
A single questionnaire suitable for the objective of this
project was not found, but parts of a questionnaire devel-
oped for the Norwegian Olympic and Paralympic Com-
mittee and Confederation of Sports Athletes (unpublished
data, 1996) was used. The questionnaire composed for this
study was tested for validity and reliability, in a pilot study
(not shown), with 15 female cross-country skiers aged
16–28 years.
The original questionnaire regarding the athlete’s health
situation consisted of 38 questions. For the present study,
these were selected: Questions 1–4, general information,
such as age, weight, height, attendance at ski high school, and
use of a training diary; Question 5, volume of total training
(skis, roller skis, running, cycling, strength, paddling, etc)
and skating-specific training (skis and roller skis) per month;
Questions 9 and 10, musculoskeletal disorders (yes/no),
training cessation and/or alternative training because of
these problems (yes/no), and total duration of training ces-
sation and alternative training; Question 12, identification
of musculoskeletal disorders relating to the part of the body
affected, duration, and month of occurrence.
Volume of training
0
10
20
30
40
50
60
May
June
July
August
September
October
November
December
January
February
March
April
Mean hours
Senior total training
Junior total training
Senior skating
Junior skating
Figure 1 Mean volume of total training and skating-specic training hours per month, for junior and senior athletes participating in this study.
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The questionnaire was based on self-report; however,
several of the musculoskeletal problems reported by the
athletes had been diagnosed by medical personnel. In this
study and in the questionnaire, musculoskeletal disorder
was defined as an injury in or problem related to muscles,
tendons, ligaments, bursas, or the skeleton. “Preseason” was
defined as the period from May–October, and “ski season”
was defined as the period from November–March. Body
mass index (BMI) was calculated, using the athletes’ height
and weight, as kg/m2. “Volume of training” was defined as
hours per month.
Analysis
All statistical analyses were performed using SPSS/PASW
v. 19.0 (IBM, Armonk, NY, USA). Univariate statistical
methods were used. The subject characteristics, such as
age, weight, height, BMI, the total amount of training, and
the amount of skating (skis and roller-skis), are reported as
means and confidence interval (CI = 95%). The junior and
senior group were compared using independent samples
t-test and the P-value (2-tailed) estimated by the t-test for
equality of means. Factors such as attending ski high school,
participating in other sports, and use of a training diary were
analyzed by descriptive statistics, with the P-value found by
Pearson’s Chi-square test.
The prevalence of musculoskeletal disorders, body parts
affected, number of disorders/injuries per subject, month
of occurrence, and duration of symptoms are presented
as number of participants and percent. These data were
analyzed by descriptive statistics, and the estimation of the
P-value was done using Pearson’s Chi-square test. The most
frequently affected body parts were selected and analyzed for
month of occurrence and duration. The criterion for defining
statistically significant effect was set as P-value # 0.05. The
categories “don’t know,” “no response,” and “not applicable”
were defined as “missing” in the data material before the
analyses were done. Odds ratio (OR), the risk for having
a musculoskeletal problem, was calculated as: (exposed
cases/all cases)/(unexposed cases/all cases).
Ethics
The participation in this study was voluntary, and the athletes
signed a consent letter. This project was approved by the
Regional Medical Committee for Medical Research Ethics,
Mid-Norway, and The Data Inspectorate of Norway.
Results
The mean “volume” (ie, hours/month) of total physical
training (cross-country skiing, roller-skis, running, cycling,
strength training, etc) during the 2007–2008 season was
337.3 hours (confidence interval [CI] = 297.3–377.2) for the
juniors and 478.3 hours (CI = 413.8–542.8) for the seniors.
The mean volume of total skating-specific training (skis
and roller-skis) was 114.1 hours (CI = 98.4–129.9) for the
juniors and 179.2 hours (CI = 144.6–213.9) for the seniors
(Figure 1). The mean age in the total group was 19.1 years,
and the oldest athletes were 41-years-old. The senior athletes
had a significantly higher volume of total training (P , 0.01)
and skating-specific training (P , 0.01) than did the juniors,
during the same season.
August was the month with the highest volume of total
training for the juniors (30.6 hours [CI = 26.2–35.0]); this
was June for the seniors (47.8 hours [CI = 37.7–58.0]).
Both groups had the lowest volume of total training in April
(juniors: 18.8 hours [CI = 15.2–20.8]; seniors: 21.3 hours
[CI = 15.7–26.9]). January was the month of highest vol-
ume of skating-specific training for the juniors (12.0 hours
[CI = 10.0–13.9]), whereas this was November for the seniors
(17.2 hours [CI = 12.7–21.8]).
In the total group of female athletes, 57.4% (N = 85)
reported one or more musculoskeletal disorders; this was
59.3% (N = 70) in the junior group and 50.0% (N = 15) in the
senior group, which were not significantly different (P = 0.33;
OR = 1.48). Among all participants with a musculoskeletal
disorder 57.6% (N = 49) reported one musculoskeletal dis-
order, 27.1% (N = 23) reported two disorders, 9.4% (N = 8)
reported three disorders, and 4.7% (N = 4) reported four
or more disorders. There was no significant difference in
number of disorders between the junior and senior group
(P = 0.70).
The knee (23%, N = 34) was the most frequently affected
body part, followed by the calf (12.2%, N = 18), ankle/foot
(10.8%, N = 16), lower back (10.8%, N = 16), and the thigh
(10.1%, N = 15) (Figure 2). The number of disorders per body
part per subject was not included in these numbers. There
was no significant difference between the junior and senior
group in the body parts that were most frequently affected, but
a higher rate of thigh problems was seen among the juniors
(12.7%) compared with the seniors (3.3%).
The main findings regarding duration of musculoskel-
etal disorders were that: for knee problems, 23.5% lasted
1–2 weeks and 55.9% lasted . 4 weeks; for calf problems,
72.2% lasted . 4 weeks; for ankle/foot problems, 31.2%
lasted 1–2 weeks, 37.5% lasted . 4 weeks; for lower back
problems, 87.5%: lasted . 4 weeks; and for thigh prob-
lems, 75% lasted . 4 weeks. The juniors had significant
longer duration of knee problems compared with the seniors
(P = 0.04). No significant differences in duration of symptoms
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Prevalence of musculoskeletal disorders among Norwegian athletes

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between these two groups were found related to the other
body parts. The most frequent occurrence of musculoskeletal
disorders was in the preseason (78.2%, N = 68) compared
with the ski-season (21.8%, N = 19). May (20.7%, N = 18),
with September (17.2%, N = 15) highlighted as the months
with highest occurrence of disorders during the period
of study. There was no significant difference in month of
occurrence between junior and senior groups (P = 0.63)
(Figure 3).
Most of the athletes with musculoskeletal disorders
reported that training/competition was stopped and/or that
alternative training was done, because of these problems
(Table 1 and Table 2).
Discussion
Approximately 50% of the Norwegian female biathlon
athletes experienced musculoskeletal disorders during
the 2007–2008 season. The current study was based on
self-reports, and answers were dependent on each athlete’s
understanding of the disorder manifestation and their own
symptoms. This may have increased the injury rate compared
with studies based on disorders diagnosed by medical
personnel. Comparison between the junior and the senior
athletes was difficult because of a low number of athletes in
the senior group. Although there were fewer senior athletes
than juniors, the response rate in the senior group was higher.
It is important to be aware that most of the biathlon athletes
in the current study also participated in other sports.2 There-
fore, different injury mechanisms, unrelated to participation
in biathlon, may have affected this group of athletes and led
to musculoskeletal disorders.
Few studies of musculoskeletal problems among
biathlon athletes have been found, but it is reasonable to
make comparisons with studies of cross-country skiing,
which has sport-specific demands closely related to those
of biathlon.2 Blut et al2 found a significantly higher injury
prevalence among female biathlon athletes (54.5%) com-
pared with male athletes (39.7%) during the 2008–2009
Prevalence of disorders related to part of the body
0
5
10
15
20
25
Ankle/foot
Calf
Knee
Thigh
Inguen
Hip/gluteal muscles
Lower back
Thoracal
Shoulder/upper arm
Albow/forearm
Wrist
%
Subjects with disorders
Figure 2 The prevalence of musculoskeletal disorders affecting different parts of the body.
The month of occurence of the disorder
0
10
20
30
40
50
60
70
80
90
100
May
June
July
August
September
October
November
December
January
February
March
April
Percent
Lower back
Thigh
Knee
Calf
Ankle/foot
Figure 3 The month of occurrence of the most frequent musculoskeletal disorders.
Note: The results are given in percent of athletes with the respective disorder.
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Table 1 Age, height, weight, BMI, use of training diary, education at ski high school (current or previous seasons), and participation in
other sports during the 2007–2008 season
Junior
N = 118
Senior
N = 30
All subjects
N = 148
Differences
junior/senior
Mean (SD) Mean (SD) Mean (SD) P-valuea
Age 17.4 (±1.26) 25.8 (±4.71) 19.1 (±4.15) 0.000
Height 168.0 (±0.05) 170.0 (±0.05) 168.4 (±0.05) 0.056
Weight 60.1 (±6.21) 62.0 (±5.93) 60.5 (±6.18) 0.132
BMI 21.3 (±1.96) 21.4 (±1.68) 21.3 (±1.90) 0.728
N (%) N (%) N (%) P-valueb
Ski high school 53 (45.3) 21 (70.0) 74 (50.3) 0.016
Other sports 71 (60.7) 9 (30.0) 80 (54.4) 0.003
Training diary 97 (82.9) 23 (76.7) 120 (81.6) 0.431
Notes: aSignicance based on t-test for equality of means; bsignicance based on Pearson Chi-square test.
Abbreviations: BMI, body mass index; SD, standard deviation.
Table 2 Prevalence and duration of training/competition cessation and alternative training caused by musculoskeletal disorders
Junior
(N = 70)
Senior
(N = 15)
All subjects
(N = 85)
Differences
junior/senior
N (%) N (%) N (%) P-valuea
Training/competition cessation 53 (77.9) 8 (53.3) 61 (73.5) 0.051
Missing 2 0 2
Duration of training cessation 0.484
1–3 days 3 (5.7) 2 (25.0) 5 (8.2)
4–7 days 11 (20.8) 2 (25.0) 13 (21.3)
1–2 weeks 9 (17.0) 2 (25.0) 11 (18.0)
2–3 weeks 6 (11.3) 0 (0.0) 6 (9.8)
3–4 weeks 6 (11.3) 0 (0.0) 6 (9.8)
1–3 months 8 (15.1) 1 (12.5) 9 (14.8)
.3 months 10 (18.9) 1 (12.5) 11 (18.0)
Missing 0 0 0
Alternative training 59 (88.1) 13 (86.7) 72 (87.8) 0.882
Missing 3 0 3
Duration of alternative training 0.134
1–3 days 3 (6.2) 2 (15.4) 5 (8.2)
4–7 days 6 (12.5) 5 (38.5) 11 (18.0)
1–2 weeks 7 (14.6) 1 (7.7) 8 (13.1)
2–3 weeks 2 (4.2) 1 (7.7) 3 (4.9)
3–4 weeks 8 (16.7) 3 (23.1) 11 (18.0)
1–3 months 7 (14.6) 0 (0.0) 7 (11.5)
.3 months 15 (31.2) 1 (7.7) 16 (26.2)
Missing 11 0 11
Note: aSignicance based on Pearson Chi-square test.
season. However, this was only found among senior
athletes. Difficulties may be seen in directly comparing
musculoskeletal problems among biathlon athletes and
cross-country athletes, because cross-country athletes
compete mainly in “classic” technique and to a lesser
extent, in “skating technique,” whereas biathlon athletes
compete only in “skating” technique. The prevalence of
musculoskeletal problems found in the current study is
in accordance with that found in a study by Alricsson and
Werner7 of male and female Swedish cross-country skiers
attending a ski high school, where 55% of 117 reported
of symptoms/injuries in one or several parts of the body
during the preceding 3 months. However, this is a lower
prevalence than was claimed among 690 German cross-
country skiers (69.3%).9 Bergstrøm et al5 even found that
96% of 45 Swedish ski high school athletes reported pain
in one or several parts of the body during a season.
In this study of female biathlon athletes, the lower
limbs seem to have been more affected by musculoskeletal
disorders compared with the upper limbs. This result is in
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Prevalence of musculoskeletal disorders among Norwegian athletes

Open Access Journal of Sports Medicine 2013:4
accordance with findings among cross-country skiers.6,10
The lower limbs are major contributors to power generated
in skating,11,12 and are also exposed to higher training loads
through other training, such as classic skiing, running and
bicycling, compared with the upper limbs.
Especially knee disorders, but also ankle/foot and calf
disorders, appear to be a problem for many female biathlon
athletes. These problems often occur during preseason when
athletes stop skiing and start to use running and cycling as the
major part of their training. The majority of injuries may be
caused from training activities such as running. Furthermore,
the skating technique requires knee and ankle/foot stability
in the push-off phase, and knee pain may be produced if this
stability is insufficient. Biathlon is an endurance sport and
requires a high amount of relatively repetitive training and
may be at risk for the same type of injuries found among other
endurance athletes. In the present study, a high proportion
of junior biathlon athletes reported thigh problems during
the season under study, and muscular soreness and reduced
muscle function in the thigh may be a symptom of an over-
training syndrome or unexplained underperformance.9 Bud-
gett et al13 claim that unexplained underperformance occurs
in around 10%–20% of elite endurance athletes, which is in
accordance with the findings in the current study.
Lower-back problems are often thought to be a problem
among athletes who perform cross-country skiing. This prob-
lem was present among the female biathlon athletes studied,
but the prevalence was lower compared with that found in
studies of cross-country skiers. Among both male and female
Norwegian and Swedish cross-country skiers, 44.2%, 63%,
and 67.0% of the athletes have reported low-back pain.5 In
one study, low-back pain seemed to occur more often in con-
nection with classic technique rather than in connection with
skating technique.7 Biathlon athletes have a smaller volume of
classic technique compared with cross-country skiers because
in biathlon, only skating technique is used in competition, and
classic technique is used only for low-intensity and alternative
training. The results of the current study of female biathlon
athletes showed a higher prevalence of low-back pain among
the junior athletes, which is in accordance with the findings
of Bergstrøm et al,5 who claimed that lower-back problems
were more frequent among the youngest athletes.
Most of the musculoskeletal problems reported among the
female biathlon athletes occurred during preseason, except
for the thigh and lower-back problems, which seemed to be
present during the competition season. This may be due to the
changeover period from skiing on snow to increased running,
skating on roller skies, and cycling, between April and May,
when moving patterns may be unused, the training loads may
increase to fast. However, Bahr et al8 found, in their study of
cross-country skiers, a higher rate of low-back pain during
periods with high-training and/or competition load, which
also support the findings in the current study, of low-back
problems occurring during the winter. However, a study by
Reinking and Hayes9 of cross-country runners didn’t find
any significant relationship between training distance and
exercise-induced musculoskeletal problems. Many of the
calf and the knee problems in the current study occurred in
May, when the mean volume of training was relatively low.
These findings indicate different injury mechanisms affecting
the different type of disorders. In September, many athletes
increase their training intensity and volume of roller-ski
training. These changes in training may lead to a higher risk
of musculoskeletal problems.
A prolonged duration of symptoms, duration of alterna-
tive training, and training/competition cessation because
of musculoskeletal disorders was found among the female
biathlon athletes and may indicate severe or chronic musculo-
skeletal problems. Most of the athletes with musculoskeletal
injuries reported either a stopping of training/competition
and/or alternative training because of musculoskeletal prob-
lems, but the rate was higher for alternative training. The
prevalence of training/competition cessation was high com-
pared with that in the study by Bahr et al8 on cross-country
skiers, where they reported 19.1% missed training because
of low-back pain. This may indicate more severe disorders
among juniors, but it may also indicate that the seniors, to
a larger extent, choose alternative training and try to avoid
training/competition cessation, which may have a major effect
on biathlon top-level performance.
An important strength of the current study is that all the
female biathlon athletes registered in the NSSF license list
were eligible for inclusion in the study. Further, the response
rate was relatively high, and the total number of participants
was high compared with other studies of endurance athletes.
Therefore, the results were less sensitive to individual varia-
tions and gave more precise information. Like several of the
studies of cross-country skiing, this study included both
athletes attending and not attending ski high school, and well
represents the total group of competing biathlon athletes in
Norway, including athletes with differences in training and
social environment. The majority of the participants kept a
training diary, which improved their memory of musculosk-
eletal problems during the season.
A limitation of the study is that the information was
based on the athletes’ self-reports, not diagnosis, and this
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may influence the value of the information. The numbers of
participants in the senior group was low compared with the
junior group, and this may have affected the P-value estima-
tion and reduced the validity of the data. The age difference
(16–40 years) in the group of participants may cause a risk
for participants’ semantic understanding of the questions
and the definitions. Further, a natural selection of the fittest
athletes may be present in biathlon, as in other sports; thus,
the athletes who are still participating in biathlon at senior
age may be the athletes with good health and less severe mus-
culoskeletal problems. In studying the athletes for only one
season, this scenario may have reduced the actual prevalence
of musculoskeletal disorders in this group.
Future studies should try to examine specific types of
musculoskeletal disorders and their severity in the female
biathlon sport and cross-country skiing, to better initiate
prevention. The relationship between musculoskeletal prob-
lems and the volume and type of training, and its variation
through the year, should also be investigated. Comparison
of injury mechanisms in males and females should also be
investigated, in order to better plan a type of training that
is adjusted for sex and age. Musculoskeletal disorders may
lead to dropout from the sport and to reduced physical fit-
ness and mental well-being. Optimal health is important for
athletes, for optimal performance in sport and for optimal
daily living in the future.
Conclusion
In summary, approximately half of the athletes included in
this study had one or more musculoskeletal disorders. The
knee was the part of the body most frequently affected, and
most of the musculoskeletal problems occurred in preseason,
mainly in May and September. Many of the musculoskeletal
problems were of prolonged duration, which may indicate
more severe disorders. Many of the female biathlon athletes
reported either cessation of training/competition or doing
alternative training because of their problems, which may
affect many athletes’ ability to perform. Due to requirements
of high- and repetitive training loads, often at an early age,
the risk of disorders related to overload are present. The lower
limbs seem to be more often affected by problems, and this
may indicate that the different exercises used in training
stress the same structures. The month of occurrence of symp-
toms differed somewhat between the body parts, indicating
different mechanisms provoking these problems. The results
of the study indicate that prevention of lower-limb prob-
lems must be prioritized, especially in the preseason. These
clinical findings should be translated into training plans and
injury prevention, starting at an early age.
Disclosure
The authors report no conflicts of interest in this work.
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