The use of psychological interventions in
sports has become increasingly popular' and
has been described in several publications.`
The efficacy of such interventions has been
poorly documented. Recent reviews, however,
suggest that more than 85% of studies addressing
the issue have reported significant improvement
of performance after mental training.'`'
On the other hand, the validity of these studies
has been questioned. Causality between the
psychological intervention and performance
could be inferred in fewer of the studies. The
lack of manipulation checks, appropriate controls,
and clearly described interventions has
been pointed out as other major research problems.'
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