preferentially observed in endurance athletes
(Lehmannet al. 1993). The characteristics of the
parasympathetic form of the overtraining syn-
drome are misleading to the athletes and the
coach, because the symptoms are suggestive of
excellent health. Although the pathophysiologi-
cal mechanism of both forms of overtraining is
not clear yet, it is hypothesized that both forms
reflect different stages of the overtraining syn-
drome. The sympathetic form is supposed to be
the early stage of the overtraining syndrome,
during which the sympathetic system is continu-
ously activated. During advanced overtraining,
the activity of the sympathetic system is inhib-
ited, resulting in a dominance of the parasym-
pathetic system. This would also explain the
increased proneness for hypoglycaemia during
exercise in the parasympathetic form, because
glucose counter-regulation is mediated via the
sympathetic system.
Because overtraining is difficult to diagnose, it
is most important to prevent overtraining. The
following rules and advice can be helpful to
prevent overtraining.
1 Develop a well-balanced, flexible and attrac-
tive training programme, with individual adjust-
ment when necessary.
2 Have field or laboratory performance tests at
regular intervals—for instance, during the easy
week during periodization.
3 Emphasize proper diet, which supplies suffi-
cient carbohydrate to meet the metabolic require-
ments (4–8 g · kg–1body weight during normal
training and up to 10 g · kg–1body weight during
heavy training) and also provides sufficient
amounts of other nutrients.
4 Have the athletes keep a training log in which
resting heart rate and body weight are registered.
Because behavioural signs seem to be the first
consistent signs of overtraining, it can be helpful
to use the profile of mood states scale (POMS
scale) as described by Morgan and coworkers
(1987). The POMS scale yields information about
the global measure of mood, tension, depression,
anger, vigour, fatigue and confusion. By monitor-
ing the mood state on the POMS scale, overtrain-
ing can be detected at an early stage.
In addition, or alternatively, the athletes can fill
in a self-designed visual analogue scale question-
naire, containing questions about fatiguability,
recovery, motivation, irritability and sleep.
Recent research has shown that a balanced
training programme results in an increase in
plasma glutamine concentrations, whereas a
mismatch between training and recovery is asso-
ciated with a decline in plasma glutamine con-
centrations (Rowbottom et al. 1996). Therefore,
monitoring plasma glutamine concentrations
during the training process may be helpful to
detect overtraining in its earliest stage. However,
more studies are needed to provide clear and
practical guidelines about this possibility.Treatment of overtraining
When symptoms of increased fatiguability occur,
and no other symptoms are observed, overreach-
ing or metabolic overtraining is most likely. In
that case, the training should be adjusted, mainly
by decreasing the volume.
A decrease in volume is the most important
measure to be taken. Most emphasis should be
laid on sufficient rest, recovery, and a diet that is
rich in carbohydrates and contains sufficient
amounts of trace elements, vitamins, and other
nutrients (Kuipers & Keizer 1988). Usually meta-
bolic overtraining is reversible within some days.
Systemic overtraining or overtraining syn-
drome usually requires one to several weeks for
recovery. The contributing factors should be
identified and sometimes counselling is neces-
sary. There are no specific drugs or treatments
known. Although proper nutrition is important,
there is no evidence that specific nutritional sup-
plements may be of any help to treat overtraining
or to enhance recovery.References
Barron, G.L., Noakes, T.D., Levy, W., Smith, C. & Millar,
R.P. (1985) Hypothalamic dysfunction in overtrained
athletes.Journal of Clinical Endocrinology and Metabo-
lism 60 , 803–806.
Fry, R.W., Morton, A.W., Garcia-Webb, P., Crawford,
G.P.M. & Keast, D. (1992) Biological responses to