Previous transcranial magnetic stimulation (TMS) studies showed exercise-induced depression
of motor evoked potentials (MEP). The purpose of the present study was to evaluate
changes in MEP size and central motor conduction time (CMCT) after various kinds of
exercise of daily life and sports. Changes of both central and peripheral motor conduction
were recorded immediately after predominantly aerobic (climbing stairs and jogging)
and anaerobic (press-ups, dumb-bell holding, and 400 m-run) exercise. Strength exercise
resulted in a significant decrease of MEP amplitudes. Exhausting press-ups reduced
the mean MEP amplitude by 33 % as compared to pre-exercise value, exhausting dumb-bell
holding reduced the mean MEP amplitude by 66 %. Aerobic exercises (climbing 600 steps
and jogging 50 minutes) did not significantly change MEP amplitudes. The compound
motor action potentials (registered after supramaximal peripheral electrical stimulation)
remained unchanged after each paradigm. CMCT was not significantly altered by any
of the exercises under investigation. Peripheral motor conduction time (PMCT) was
slightly lengthened by 4 % after isometric dumb-bell holding. PMCT and total motor
conduction time were decreased after aerobic exercises, probably due to an increase
of temperature of the lower extremities. In conclusion, TMS is a suitable technique
for objective evaluation of central fatigue. The present study is the first to show
its possible use in sports medicine, indicating that only exhaustive or strength exercises
result in reduced MEPs.
Key words
Transcranial magnetic stimulation - motor evoked potentials - exercise - fatigue -
sports