EEG-changes in humans during regeneration after heavy physical strain with the influence of I-theanine, an amino acid in green tea

Problem: The influence of l-theanine on relaxing effects of central nervous system in human beings was studied using electroencephalographical methods (EEG). Methods: 14 male healthy sport-students individually stressed by an bicycle-ergometer test until exhaustion once a week. After the test they recovered lying in a separate shaded room. Three test-drinks with different l-thanine content (D1 = Placebo, D2 = 50 mg, D3 = 200 mg) were given in a randomised cross-over and double-blind order after measurement (M1). All test-conditions were strictly standardized. EEG-recordings (closed eyes) were carried out at M1 = 3-, M2 = 45-, M3 = 60-, M4 = 75-, M5 = 135 minutes after physical stress with 17 electrodes of the CATEEM registered System. Absolute and relative delta , Theta , alpha 1, alpha 2, beta 1, beta 2 spectral power were examined. Results: Significant reductions in all frequencies (exception Theta -power) were found in early recovery, being not significantly influenced by test drinks. Qualitative different behaviour trends were found in frontal-, central-, occipital- regions with increased alpha 1, Theta (frontal) and decreasing beta 1 relative-power earlier in recovery with D3. These findings were related to relaxing effects. After ingestion of 1-theanine alpha 2-, beta 1-power at occipital regions decreased faster (M2) to placebo recovery levels (M3/M4). Thus it may be concluded that 1-theanine has no pharmaceutical effect on the down regulation system but supports the physiological mechanisms during recovery after physical stress in human brain.