Prevalence of non-functional overreaching and the overtraining syndrome in Swiss elite athletes

Abstract

Objectives: Fatigue and unaccountable underperformance are common for athletes, but there is a lack of empirical data regarding the prevalence of non-functional overreaching (NFOR) and the overtraining syndrome (OTS). Using the overtraining definition of the European College of Sport Science (ECSS), the present study aimed to explore the prevalence, symptoms and associated factors of NFOR/OTS across Swiss elite athletes in various sports. Method: 139 Swiss elite athletes (63 males and 76 females, Mage = 23.6, SD age = 5.6 y) from 26 different sports completed al 7-item online survey about underperformance and symptoms of NFOR/OTS. 95% of the sample represented Switzerland in their sport. Athletes were classified as NFOR/OTS by according to the overtraining definition of the ECSS. Data were analysed using Mann-Whitney U nonparametric tests and ANOVAs. Results: 9% of the athletes were classified as OTS and 21% as NFOR at least once in their career. The prevalence was significantly higher in medium-physical demand sports than in low-physical demand sports (p -.02). There were no significant differences in the NFOR/OTS prevalence between individual and team sports and female and male athletes. Competition level and training load had also no significant influence on the NFOR/OTS prevalence, although low-physical demand sports trained significantly less than medium- and high-physical demand sports. Injury/illness, loss of weight and sleep disturbance rates were significantly higher in the NFOR/OTS group. More than 70% of the NFOR/OTS athletes reported loss of motivation and emotional disturbances. Conclusions: The NFOR/OTS career prevalence rate of Swiss elite athletes can be estimated at approximately 30%. NFOR/OTS is accompanied by biopsychosocial signs of maladjustment, e.g., emotional disturbances, loss of motivation, sleep disturbances, injury/illness and weight loss, but training load is not a predictor of NFOR/OTS.

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ReviewOriginal article
Zusammenfassung
Absicht: Müdigkeit und unerklärbare Leistungsschwächen
treten bei Sportlern häug auf. Dennoch fehlen empirische
Daten bezüglich der Prävalenz von non-functional over-
reaching (NFOR) und des Übertrainingssyndroms (OTS).
Ziel der vorliegenden Studie war es, unter Verwendung der
European College of Sport Science (ECSS) Übertrainingsde-
nition die NFOR/OTS Prävalenz, Symptomatik und beglei-
tenden Faktoren bei Schweizer Spitzensportlern unterschied-
licher Sportarten zu bestimmen.
Methode: 139 Schweizer Spitzenathleten (63 Männer, 76
Frauen; Mage = 23.6, SDage = 5.6) aus 26 Sportarten füllten
einen 17-item Onlinefragebogen zu Leistungsschwäche und
NFOR/OTS Symptomen aus. 95% der Sportler hatten die
Schweiz in ihrer jeweiligen Sportart schon vertreten. Unter
der strikten Verwendung der ECSS Übertrainingsdenition
wurden die Sportler als NFOR/OTS klassiziert. Zur Daten-
analyse wurden Mann-Whitney U Tests und Faktorenanaly-
sen verwendet.
Resultate: 9% der Sportler wurden als OTS und 21% als
NFOR klassiziert. Die Prävalenz war in moderat-körperlich
beanspruchenden Sportarten höher als in gering-körperlich
beanspruchenden Sportarten (p = .02). Keine signikanten
Unterschiede in der NFOR/OTS Prävalenz bestand zwischen
Individual- und Teamsportarten sowie zwischen männlichen
und weiblichen Sportlern. Wettkampfniveau und Trainings-
belastung hatte keinen signikanten Einuss auf die NFOR/
OTS Prävalenz, obwohl gering-körperlich beanspruchende
Sportarten signikant weniger trainierten als moderat-kör-
perlich beanspruchende Sportarten. Verletzungen/Krankhei-
ten, Gewichtsverlust und Schlafstörungen sind in der NFOR/
OTS Gruppe signikant höher vertreten. Mehr als 70% der
als NFOR/OTS klassizierten Sportler berichteten über Mo-
tivationsverlust und emotionale Beeinträchtigungen.
Konklusion: Die NFOR/OTS Karriereprävalenz von Schwei-
zer Spitzensportlern kann in etwa auf 30% geschätzt werden.
NFOR/OTS ist von bio-psycho-sozialen Fehlanpassungssym-
ptomen wie emotionaler Beeinträchtigung, Motivationsver-
lust, Verletzungen/Krankheiten, Schlafstörungen und Ge-
wichtsverlust begleitet. Die Trainingsbelastung ist kein
Prädiktor von NFOR/OTS.
Daniel Birrer1, Daniel Lienhard1, Craig A. Williams2, Philipp Röthlin1 & Gareth Morgan1
1 Swiss Federal Institute of Sports Magglingen, Switzerland
2 Children’s Health and Exercise Research Centre, Sport and Health Sciences, University of Exeter, United Kingdom
Prevalence of non-functional overreaching
and the overtraining syndrome in Swiss elite
athletes
Schweizerische Zeitschrift für Sportmedizin und Sporttraumatologie 61 (4), 23–29, 2013
Abstract
Objectives: Fatigue and unaccountable underperformance are
common for athletes, but there is a lack of empirical data
regarding the prevalence of non-functional overreaching
(NFOR) and the overtraining syndrome (OTS). Using the
overtraining denition of the European College of Sport Sci-
ence (ECSS), the present study aimed to explore the preva
-
lence, symptoms and associated factors of NFOR/OTS across
Swiss elite athletes in various sports.
Method: 139 Swiss elite athletes (63 males and 76 females,
Mage = 23.6, SDage = 5.6 y) from 26 different sports complet-
ed a1 7-item online survey about underperformance and
symptoms of NFOR/OTS. 95% of the sample represented
Switzerland in their sport. Athletes were classied as NFOR/
OTS by according to the overtraining denition of the ECSS.
Data were analysed using Mann-Whitney U nonparametric
tests and ANOVAs.
Results: 9% of the athletes were classied as OTS and 21% as
NFOR at least once in their career. The prevalence was sig-
nicantly higher in medium-physical demand sports than in
low-physical demand sports (p = .02). There were no signi-
cant differences in the NFOR/OTS prevalence between indi-
vidual and team sports and female and male athletes. Compe-
tition level and training load had also no signicant inuence
on the NFOR/OTS prevalence, although low-physical demand
sports trained signicantly less than medium- and high-phys-
ical demand sports. Injury/illness, loss of weight and sleep
disturbance rates were signicantly higher in the NFOR/OTS
group. More than 70% of the NFOR/OTS athletes reported
loss of motivation and emotional disturbances.
Conclusions: The NFOR/OTS career prevalence rate of Swiss
elite athletes can be estimated at approximately 30%. NFOR/
OTS is accompanied by biopsychosocial signs of maladjust-
ment, e.g., emotional disturbances, loss of motivation, sleep
disturbances, injury/illness and weight loss, but training load
is not a predictor of NFOR/OTS.
Keywords:
staleness, performance maladaptation, training load, adjust-
ment disorder, sleep disturbance

24 Birrer D. et al.
Introduction
Overtraining is a widely used term in sport sciences. A liter-
ature search on SportDiscus with the term overtraining re-
vealed 813 articles published between 1960 and 2013. If the
search is extended by the terms of staleness and overreaching,
terms that are sometimes interchangeably used by sport sci-
entists, the result list increases to 935. Conversely, in spite of
wide spread interest in overtraining it seems to be one of the
most misunderstood and misconceived phenomenon in sport
sciences. One reason for the lack of understanding is the lack
of common or consistent terminology used in the eld of
overtraining research (Halson and Jeukendrup, 2004). For
example, to label the phenomenon with the term “overtrain-
ing” may be a confounding factor itself. As a verb it charac-
terises an action, a process. In the case of “overtrain” it con-
veys a process of too much training. Too much that is, in the
sense of, too much for a positive adaptation to the training
load. Yet, overtraining as a phenomenon is a state, an out-
come of the process of too much training in combination with
not enough regeneration. It is generally caused through expo-
sure to physiological stress, but developed in combination
with psychological and/or social stressors (Kellmann, 2002;
Meyers and Whelan, 1998). Essentially, athletes train to en-
hance and optimize performance. Performance increases are
achieved when the intensity, duration and total workload of
exercise are appropriate for the actual performance level and
the workloads are followed by adequate periods of rest, which
will lead to recovery. A positive training adaptation over time
requires gradually higher training loads. However, a rigorous
training schedule with insufcient recovery caused through
other sources of non-training stress may lead to maladaptive
responses in form of performance decrements along with oth-
er symptoms.
Following the denition of the European College of Sport
Science position statement on the overtraining syndrome
(Meeusen et al., 2006), such an accumulation of training and
or non-training stress resulting in short-term performance
decrement is labelled overreaching (OR). This form of short-
term OR is often planned and necessary (e.g., when going to
a training camp and intensied training results in a decline
in performance). When these periods of short-term OR are
followed by appropriate periods of rest and recovery, super-
compensation follows, i.e., the athlete exhibits an enhanced
performance compared to the baseline level. The needed rest
time to recover and achieve such a benecial effect may re-
quire days or weeks. Therefore, it is possible to recover from
a state of short-term OR within a 2-week period (Halson et
al., 2002; Kreider et al., 1998; Lehmann et al., 1999; Stein-
acker et al., 2000). Such short-term OR periods are general-
ly not accompanied by other severe psychological or physi-
ological symptoms albeit short-term performance decreases.
Accordingly to the denition of the European College of
Sport Science position statement on the overtraining syn-
drome (Meeusen et al., 2006) these necessary short-term
periods of maladaptations are labelled functional overreach-
ing (FOR).
However, when athletes do not sufciently recover from
the short-term performance decreases, because the appropri-
ate balance between stress and recovery or other stress factors
limited the recovery, then non-functional overreaching
(NFOR) emerges (Meeusen et al., 2006). In a state of NFOR
an athlete needs weeks or months to recover and a two week
rest period or less will not result in a performance restoration.
The key clinical symptom, prolonged performance decrement
and fatigue, is often accompanied by psychological and hor-
monal disturbances, such as mood disturbances, (Hooper et
al., 1997; Raglin, 1993), loss of motivation (Meeusen et al.,
2006), loss of appetite, unexplained weight loss, and sleep
disturbances (Armstrong and VanHeest, 2002; Kenttä et al.,
2001; Lehmann et al., 1999; Meeusen et al., 2006).
The distinction between NFOR and the overtraining syn-
drome (OTS) is ambiguous. Recovery from an OTS will take
months to years. Therefore in the denition of the European
College of Sport Science position statement on the overtrain-
ing syndrome, Meeusen and colleagues (2006) emphasize the
use of the expression “syndrome” to express the multifacto-
rial etiology of OTS and that exercise is not the sole causative
factor but several other factors such as inadequate nutrition,
illness, psychosocial stressors (work-, team-, education-, fam-
ily-related) are leading to the prolonged maladaptation, sim-
ilar to the one that can be observed in an adjustment disorder
(Jones and Tenenbaum, 2009).
Despite extensive literature on overtraining the prevalence
of FOR, NFOR and OTS has not yet been clearly established
(Kreher and Schwartz, 2012). Many of the studies lack a
clear denition and classication of FOR, NFOR or OTS and
are often based on small numbers of athletes. The prevalence
ranges between around 60% in elite male and female dis-
tance runner (W. P. Morgan et al., 1987) and 10% in one
single season (Hooper et al., 1997). The prevalence rate
seems to be different in age groups, types of sport and com-
petitive level. Among adolescent athletes the prevalence rate
seems to be approximately 30%. Raglin and colleagues
(2000) found in a cross-cultural study (Japan, United States,
Sweden, and Greece) an incident rate of 35% in young swim-
mers (Mage = 14.8; SD = 1.4 yr). In slightly older Swedish
athletes (Mage = 17.9 yr) Kenttä and colleagues (2001) report-
ed an incidence rate of 37%. With a more restrictive deni-
tion of overtraining Matos et al. (2011) found most recently
a prevalence rate of 29% in young English athletes (Mage =
15.1; SD = 2.0 yr). Prevalence rate in older elite athletes does
however appear to be lower. Gould and colleagues (Gould
and Dieffenbach, 2002; 2002) reported that 28% of Ameri-
can athletes at the Atlanta Olympic games and 10% of the
Nagano Olympic Games stated they were overtrained in the
90-days period before the Games, resulting in signicant
underperformance at the Games. However, overtraining di-
agnostic criteria were very supercial. Koutedakis and Sharp
(1998) reported lower incidence rates of 15% for members of
the British National Teams and/or Olympic squads over a
12-month training season. In younger athletes, the preva-
lence of overtraining is signicantly increased in individual
sports, females, and low physical demanding sports (Kenttä
et al., 2001; Matos et al., 2011). The ndings that overtraining
is more common in adolescent elite sport than in adult elite
sport is somewhat contradictory (Kenttä et al., 2001; Matos
et al., 2011). Whether overtraining is more common in elite
individual sport, elite females and elite physical low demand-
ing sport is not clear (Gould and Dieffenbach, 2002; Gould
et al., 2002).
To date there is a lack of clear prevalence rates of FOR,
NFOR and OTS in elite sports. More specically, no data

Prevalence of NFOR and OTS in Swiss elite athletes 25
exists regarding prevalence rates in Swiss elite athletes. The
knowledge about the incidence of such performance malad-
aptations would help coaches, sport scientists and sports phy-
sicians to prevent, detect and treat NFOR and OTS. There-
fore, the present study aimed to assess the prevalence,
symptoms and associated factors of NFOR/OTS across a va-
riety of sports in Swiss elite athletes.
Methods
Participants and procedures
One hundred thirty-nine Swiss elite athletes (63 males and
76 females) from 26 different sports and 31 different disci-
plines volunteered to complete an online survey, which was
part of a bigger research project. Athletes received the link
of the online survey from their national sport associations.
The survey was conducted using the Unipark online research
platform (see http://www.unipark.info). One hundred and
thirty-two (95% of the sample) had represented Switzerland
in their respective sport. A total of 28% of the athletes ranged
their current competition level as international top, 16.5 % as
European top and 52.5% as National top. A total of 3% of the
athletes ranked themselves as competing on the second high-
est national level. Numbers of competition per year ranged
between 6 and 60 with a mean of 25 (SD = 24.2) with curling
and cycling reporting the most competitions per year. Mean
training hours per week were 14.3 hours (SD = 6.2) and
ranged between 6 hours and 30 hours per week. Mean age
was 23.6 years (SDage = 5.6, age range: 17–53). The research
was conducted in accordance with APA ethical guidelines.
All athletes provided informed consent.
Measures
To diagnose overtraining an adapted version of the Matos
and colleagues’ survey was used (2011). The survey consisted
of typical diagnostic questions regarding unexplained pe-
riods of underperformance, periods of training reduction or
periods of complete rest, both caused by underperformance,
as well as clinically identied symptoms of overtraining such
as loss of weight, loss of motivation, sleep problems, injury
history and mood disturbances (Meeusen et al., 2006). If the
item “Have you ever had a time when you felt very fatigued
every day and your performance signicantly decreased for
long periods of time (e.g., weeks to months) even though you
were training, beforehand you have not been sick or no
illness was diagnosed?” was answered with yes, it was cate-
gorized as overreaching or overtraining. To classify an epi-
sode as FOR, NFOR or OTR we asked for the duration of
the episode and if the athlete reduced training or even
stopped training to cope with the unexpected underper-
formance. If the unexplained performance decrease lasted
longer than two months we categorized it as OTS, except
when rest or training reduction of less than two weeks in-
duced an immediate performance restoration. In that case,
we categorized the episode as FOR. If the performance de-
crease and the prolonged fatigue lasted less than one month
and a rest period or training reduction led into performance
restoration, it was also categorized as FOR. Additionally,
episodes lasting less than one month with at least two out of
four additional overtraining symptoms (mood disturbances,
loss of motivation, sleep disturbances and unexplained loss
of weight) were categorized as NFOR. But cases without
these additional symptoms were categorized as FOR. By
choosing this procedure a very conservative strategy to de-
cide whether an athlete should be categorized as FOR,
NFOR or OTS was adopted.
Statistical analysis
Descriptive statistics are reported as mean, standard devia-
tion and percentages. Differences between the forms of over-
training states were determined using nonparametric tests
(Mann-Whitney U) or analysis of variance (ANOVA). As a
measure of the energy expenditure the MET rates of the
Compendium of Physical Activities (Ainsworth et al., 2011)
were used to classify the various sports in physical low, mid-
dle and high demanding sports (low physical demand = MET
< 6; middle physical demand = MET between 6 and 12; high
physical demand = MET > 12). If the Compendium did not
provide a MET for a certain sport we relied on another refer-
ence source (Jette et al., 1990).
Results
Prevalence
Fifty-four athletes (39%) reported that they had experienced
at least one period when they felt very fatigued every day and
their performance signicantly decreased for long periods of
time (e.g., weeks to months). On average the athletes had ex-
perienced these episodes 1.8 times in their career (SD = 1.1,
range 1–5). The majority of the athletes (a total of 32), report-
ed a duration of these periods less than one month. Eleven
athletes had a duration between one and two months, ve
between two and three months, four between three and six
months and two over six months. Forty-three athletes (repre-
senting 31% of the sample) reported that they had faced pe-
riods in their training when they could not cope with the re-
quired training intensity/load. However, not all of the athletes
experiencing longer periods of fatigue and performance dec-
rements or reporting longer periods where they were not able
to cope with the required training loads were categorized as
NFOR/OTS. If athletes did have a training break or reduced
their training for less than 14 days resulting in the restoration
of the previous performance level, athletes were categorized
as FOR. A total of 29 athletes did reduce their training vol-
ume and/or intensity and/or did have a training break as a
consequence of the performance decrement. Twenty had a
performance improvement after this break, but 14 needed a
break longer than 14 days for performance restoration. Fur-
thermore, nine athletes reported a training break not restoring
their performance level, even though ve out of this group
had a training break for longer than 14 days.
In summary, 12 athletes stating they had a performance
decrease and felt very fatigued for a long period have been
categorized as having had at least one OTS in their past ath-
letic career (9 % of the total sample). Therefore, 29 athletes
(21 % of the total sample) have been classied as NFOR and
twelve athletes (9% of the total sample) as being FOR. In
total 61% have not been classied as overreached or over-
trained so far in their career.

26 Birrer D. et al.
Sports categories
Table 1 gives an overview of the prevalence of NOR/FOR
and NFOR/OTS across different sports, for low, medium and
high MET and individual and team sports. The NFOR/OTS
prevalence differences between the low MET (MET < 6), the
middle MET (MET between 6 and 12) and the high MET
(MET > 12) are marginally signicant (p = .056). The NFOR/
OS prevalence in low MET sports is signicantly smaller
than in middle MET Sports (p = .02). However, there are no
signicant differences regarding the NFOR/OTS prevalence
between middle MET Sports and high MET sports (p = .25)
as well as low MET sports and high MET Sports (p = .18).
There are also no differences between individual (29%) and
team sports (30%) athletes. Because of the small sample num-
bers we did not test for differences between various sports.
Table 1: Prevalence of NOR/FOR and NFOR/OTS across individual and team sports according to low, medium and high
MET [absolute numbers and percentage presented].
Category and sports (MET)  NOR + FOR NFOR + OTS
nAbsolute % Absolute %
Low MET (< 6) 29 25 86.2 4 13.8
Curling (4) 16 15 93.8 1 6.3
Shooting (3) 9 7 77.8 2 22.2
Table tennis (4) 3 3 100.0 0 0.0
Athletics, throw disciplines (4) 1 0 0.0 1 100.0
Medium MET (6–12) 66 41 62.7 25 37.3
Floorball (10.3) 12 8 66.7 4 33.3
Judo (10.5) 8 3 37.5 5 62.5
Athletics, mixed (6–10) 8 4 50.0 4 50.0
Handball (12) 7 4 57.1 3 42.9
Trick cycling (8.5) 5 2 40.0 3 60.0
Horse riding (7) 5 4 80.0 1 20.0
Artistic gymnastics (7) 3 3 100.0 0 0.0
Badminton (7) 3 2 66.7 1 33.3
Ski jumping (7) 3 2 66.7 1 33.3
Fencing (6) 3 3 100.0 0 0.0
Volleyball (6) 3 3 100.0 0 0.0
Nordic combined (11) 1 0 0.0 1 100.0
Downhill/4Cross (8.5) 1 0 0.0 1 100.0
Beach Volleyball (8) 1 1 100.0 0 0.0
Climbing (8) 1 1 100.0 0 0.0
Tennis (7.3) 1 0 0.0 1 100.0
Wrestling (6) 1 1 100.0 0 0.0
High MET (>12) 44 32 70.6 12 29.4
Orienteering (19) 18 14 77.8 4 22.2
Cycling (16) 8 6 75.0 2 25.0
Athletics, middle-distance (18) 5 3 60.0 2 40.0
Rowing (12.5) 5 2 40.0 3 60.0
Athletics, marathon (14.5) 4 4 100.0 0 0.0
Canoe (12.5) 2 2 100.0 0 0.0
Figure skating (14) 1 0 0.0 1 100.0
Triathlon (13.8) 1 1 100.0 0 0.0
Individual Sports 116 82 70.7 34 29.3
Team Sports 23 16 69.6 7 30.4
Male 63 48 76.2 15 23.8
Female 76 50 65.8 26 34.2
Total 139 98 70.5 41 29.5
Note: NOR = No overreaching, FOR = Functional overreaching, NFOR = Non functional overreaching, OTS = Overtraining syndrome, Mixed = Sprint,
hurdles, jump disciplines, decathlon, heptathlon. Sports are ranked according to sample size.

Prevalence of NFOR and OTS in Swiss elite athletes 27
Training volume, number of competitions
There were no statistically signicant differences regarding
the training hours (NOR/FOR = 14.0 hrs per week; NFOR/
OTS = 14.5 hrs per week; F(1/137) = .18, p = .67), trainings
per week (NOR/FOR = 7.8 trainings per week; NFOR/OTS
= 7.5 trainings per week; F(1/137) = .09, p = .77) and numbers
of competitions per year (NOR/FOR = 26 competitions per
year; NFOR/OTS = 22 competitions per year; F(1/137) = 2.87,
p = .09) between the NOR/FOR and the NFOR/OTS groups.
Gender, competitive level
The prevalence of NFOR/OTS was higher in females (34.2%)
than in males (24.8%), but the difference was not statistically
signicant (p = .18). Analysis of variance also revealed no
signicant difference between NOR/FOR and NFOR/OTS
regarding the competition level (p = .63). However, the high-
est NFOR/OTS prevalence was present in the international
top level group with 35% and the lowest in the European top
group with 22%. The national top group revealed a NFOR/
OTS prevalence rate of 27%.
Accompanying NFOR/OTS symptoms
The frequency of the most often reported accompanying
NFOR/OTS symptoms are presented in Figure 1. Addition-
ally it is also presented if the athletes maintained a training
diary.
Seventy-one percent of the NFOR/OTS categorized ath-
letes reported that they suffered a signicant loss of motiva-
tion during the NFOR/OTS episode. Seventy-three percent
of the NFOR/OTS group reported that they felt negative emo-
tions, e.g. dejection, sadness, depression, moodiness, anger,
frustration, anxiety, existential fear, helplessness, lack of
self-condence, lack of self-worth, self-doubt, fear of failure,
weariness, loneliness, aggression, stress, fatigue, dissatisfac-
tion and desperation.
Discussion
The aim of the present study was to explore the prevalence
rate, symptoms and associated factors of overreaching/over-
training in Swiss elite athletes. Following the overtraining
denition of the European College of Sport Science position
statement on the overtraining syndrome (Meeusen et al.,
2006), a more conservative strategy was adopted to catego-
rize athletes into NOR, FOR, NFOR and OTS groups. The
overall prevalence rate of NFOR/OTS in the investigated
sample was 29%. The results are in line with ndings in ad-
olescent athletes (Kenttä et al., 2001; Matos et al., 2011) and
elite athletes (Gould and Dieffenbach, 2002; Gould et al.,
2002). Nonetheless, athletes in the above cited studies are
much younger, and it can be expected that the prevalence rate
should increase during an athletic career. For elite athletes
Gould and colleagues (Gould and Dieffenbach, 2002; 2002)
reported a three month incidence rate between 10 and 28%
and Koutedakis and Sharp (1998) 15% in a twelve month
cycle. In the present study, a life time prevalence rate was
measured, therefore the presented incidence rates can be re-
garded as lower than in previous studies. This may be because
of the use of a more restricted denition and categorization
of FOR/NFOR/OTS. Thirteen athletes that have been cate-
gorized as functional overreached might have been catego-
rized as NFOR in other studies. A less conservative NFOR/
OTS categorisation would have increased the prevalence rate
to 39%. Nevertheless, the OTS rate in our sample was close
to 10%. The present research shows that almost one third of
Swiss elite athletes experience NFOR/OTS issues sometimes
during their career, which can have a serious effect on their
health and well being.
The duration of the NFOR/OTS episodes ranged between
several weeks and more than six months. However, the majo-
rity of the athletes with the symptoms of prolonged fatigue and
performance decrement reported a performance impairment
of several weeks but less than one month. Twenty-nine athletes
reported that they reduced their training regime or even inter-
vened with a training break. Some of them regained their per-
formance level after this intervention, but only six were suc-
cessful with a reduction of less than 14 days. It can be assumed
that a reduction of the training regime of 14 days, as recom-
mended by sport scientists (Halson et al., 2002; Kreider et al.,
1998; Lehmann et al., 1999; Steinacker et al., 2000) for regai-
ning an adequate performance level after functional overre-
aching, would help a signicant number of athletes experien-
cing FOR to prevent them from developing a NFOR or OTS.
In contrast to other ndings (Kenttä et al., 2001; Matos et
al., 2011; Raglin et al., 2000), the rate of NFOR/OTS did not
differ between individual and team sports in the present sam-
ple. However, we found that the prevalence rate of middle
MET sports was signicantly higher than in low MET sports.
Although, the low MET sports trained signicantly less (M
= 11.8 hrs; SD = 5.1) than the middle MET sports (M = 15.3
hrs; SD = 6.9) (F(2/136) = 3.45, p = .04), no inuence of the
training volume per week, the number of trainings per week
and the numbers of competitions per year on the NFOR/OTS
incidence was observed. The reason for the observed preva-
lence difference between these types of sports seems not to
stem from the higher amount of training volume or energy
expenditure, but may lie in other factors inherent to medium
MET sports, such as demands of the sports culture or pres-
sure for nancial rewards.
As expected, a greater percentage of females (34%) were
categorized as NFOR/OTS compared with males (24%). Al-
though, the results are not statistically signicant, they are in
line with ndings of studies on young athletes (Kenttä et al.,
2001; Matos et al., 2011). Currently, it is not clear if these
ndings reect the conicts female athletes face when they
strive for excellence, which may lead to identity confusion
0
10
20
30
40
50
60
More than 5
injuries or illness
per year
Loss of weight
without obvious
reason
Often sleep
disturbances
Training diary
Athletes in %
NOR/FOR
NFOR/OTS
** *
*
Figure 1: Accompanying symptoms of overreaching/overtraining for the
NOR/FOR and NFOR/OTS groups. *Signicant difference between groups
(p < .05). **Signicant difference between groups (p < .01).

28 Birrer D. et al.
(Matos, et al., 2011) or if it is caused by differences between
the various sports types. For instance, Kenttä et al. (2001)
reported that 75% of gure skaters (a typical female sport) in
their sample have been stale. In fact, the prevalence of NFOR/
OTS differs considerably in different sports. In our sample
judo players reported a NFOR/OTS prevalence of 63%,
whereas curling players reported a prevalence of 6%. This
mirrors ndings from other researchers. Matos et al. (2011)
reported incidence rates between 50% (swimming) and 7%
(eld hockey), Kenttä and colleagues (2001) between 94%
(badminton) and 17% (golf), and Gould and Dieffenbach
(2002) between 80% (synchronized swimming, another typi-
cal female sport) and 6% (shooting). The presented ndings
imply that the reason for the prevalence differences lies not
primarily in the physical demand of a certain sport, expressed
in energy expenditures, but in other psychological or psycho-
social factors (Richardson et al., 2008). For example, orien-
teering as an extremely physically demanding sport with a
MET of 19 has a moderate NFOR/OTS prevalence rate of
22%, whereas trick cycling with a moderate MET of 8.5
showed an incidence rate of 60%. Furthermore, Morgan and
colleagues (W. P. Morgan et al., 1987) reported an incidence
rate for elite female and male long distance runners of over
60%. The prevalence rate in the presented runner subsample
was much lower. None of the four elite marathon runners
reported signs of overreaching or overtraining syndrome. The
prevalence in the middle distance runner was 40%. It can be
assumed that these differences may be due to cultural diffe-
rences, differences in the sports organisation, but also caused
by the small sample size, where a specic coach motivational
climate can inuence signicantly the group.
In accord with previous authors, we concur that NFOR/
OTS is not the result of too much training, but an imbalance
between training as well as non-training stress and recovery.
If this imbalance exists for a longer period and the athlete is
not able to cope with this disequilibrium a maladaptation
with a wide range of clinically signicant symptoms of poor
adjustment such as fatigue, depression, bradycardia, immu-
nological suppression (especially upper respiratory tract in-
fection), loss of motivation, insomnia, irritability, agitation,
hypertension, tachycardia, restlessness, anorexia, weight loss,
lack of mental concentration, anxiety, heavy, and/or sore stiff
muscles (Armstrong and VanHeest, 2002; Jones and Tenen-
baum, 2009; Kreher and Schwartz, 2012). In fact, the NFOR/
OTS athletes reported most of the above symptoms. Almost
30% of the NFOR/OTS athletes had more than ve injuries
or illness per year; more than 30% reported weight loss with
no obvious reason and more than 35% described suffering
often from sleep disturbances. This multifaceted nature of the
athlete’s maladjusted state has to be considered when treating
NFOR athletes or athletes with an OTS.
The fact that more than 70% of the NFOR/OTS athletes
reported emotional disturbances suggests that athletes may
detect early signs of overreaching by themselves if they ac-
cept mood disturbances as a valuable warning sign. This
would give them the chance to discuss a reduction of training
intensity/load with their coach and/or increase their recovery
actions to avoid performance maladaptation (Kenttä et al.,
2001). The emotional aspect underlines the importance not
only of an increased self-awareness, but more precisely the
ability to read and interpret signs of physical and psycholog-
ical stress. In this context, Birrer and colleagues (2012) un-
derlined the possible value of mindfulness for elite athletes.
Fortunately sport scientists have realized that athletes en-
counter stress from sources that are not only physiological in
nature, but also psychological and social in origin (Smith,
2003). To identify sports with a higher risk of developing
states of NFOR/OTS factors inherent in the sport, the fol-
lowing points should be considered: sports culture within that
sport, social economic factors, like professionalization, sport-
school solutions, training demands (endurance, mixed de-
mands, strength, metabolic system) (Birrer and Morgan,
2010), training times in the day, environmental factors (Hen-
riksen et al., 2010), coach autonomy support, contextual mo-
tivation, situational motivation (Lemyre et al., 2008). For ex-
ample, team sports on the highest level, which demand very
high training loads, but cannot provide professional struc-
tures so that players do not need to have another occupation,
e.g., Swiss handball or oorball players, may be more in dan-
ger to develop NFOR/OTS than fully professionalized team
sports, e.g., football or ice hockey. To identify individuals
with a higher risk to develop NFOR/OTS psychological fac-
tors like self-determined motivation, unidimensional identity,
sports-life domain conicts (G. Morgan et al., 2013) or mind-
fulness (Birrer et al., 2012) could be valuable constructs.
A number of limitations should be recognised. Although
these participants provide excellent ecological validity for ta-
lented sports men and women in Switzerland, ndings are li-
mited by the sample size, the homogeneous competition level
of the sample and the limited number of sports, (e.g. football
and ice hockey are two of the most popular sports in Switzer-
land, which have not been studied). Another potential limita-
tion of the study could be that overreaching was assessed
through a self report measure, which may have inuenced the
results through participant’s bias and poor memory recall.
However, the words overreaching or overtraining were not
mentioned in the questionnaire so as to reduce a possible bias.
Summary and conclusions
Adopting the denition of the European College of Sport Sci-
ence position statement on the overtraining syndrome the
NFOR/OTS career prevalence rates of Swiss elite athletes
may be estimated at approximately 30%, with various sports
differing signicantly in their incidence rate. This may be due
to specic demands of the different sports cultures. Coaches
are well advised when suspecting NFOR/OTS to plan a train
-
ing break or training reduction of 14 days in order to give
their athletes enough time to recover from a possible FOR.
Too much training is generally not the sole reason for NFOR/
OTS. Usually it is a combination of biopsychosocial stressors,
which lead to maladaptation or maladjustement, and if the
athlete (and/or the coach) does not respect the appropriate
balance between stress and recovery thus ignoring early signs
such as prolonged fatigue, mood disturbances or loss of mo-
tivation, then overreaching will ensue. Therefore, athletes
should enhance their self-awareness to detect such early signs
of overreaching. When treating NFOR/OTS athletes, it has
to be considered that the key clinical symptom, prolonged
performance decrement and fatigue, will be accompanied by
a multitude of biopsychosocial symptoms, which require as-
sistance by relevant specialists, e.g., psychologists.
Future research should try to identify sports (culture),
sports environments and individuals at risk for developing
NFOR/OTS. Therefore, the present study should be replica-
ted with a representative cross-cultural sample of different
sports, age groups and competitive level.

Prevalence of NFOR and OTS in Swiss elite athletes 29
Address corresponding author:
Daniel Birrer, Swiss Federal Institute of Sports Magglingen,
Switzerland, daniel.birrer@baspo.admin.ch, EHSM Ressort
Leistungs sport, 2532 Magglingen, phone: +41 32 327 62 63
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