Contralateral Comparison Of Beta-band Oscillations In The Motor Cortex Following Blood Flow Restriction Training

Beta-band (13-30 Hz) oscillations within the human motor cortex occur with the movement of limbs during voluntary muscular activation. Analysis of beta-band frequencies in the motor cortex compares the right and left hemispheres during contralateral isometric muscle contractions of the tibialis anterior (TA). PURPOSE: The purpose of this study was to compare the responses of beta-band mean power frequency (MPF) in the motor cortex during varying isometric contraction intensities after blood flow restriction training. METHODS: 13 untrained males (age: 21.7 ± 1.7 yrs; height: 176.6 ± 5.2 cm; weight: 83.4 ± 12.4 kg) were randomly assigned to a BFR (n = 8) and non-BFR (n = 5) group. Both groups completed 8 isokinetic dorsiflexion training sessions separated by 48 hours at 30% of their session peak torque at a velocity of 60°/s. Pre and post isometric dorsiflexion trapezoidal ramp tracings were recorded at 25%, 50%, 75%, and 100% of their maximal voluntary contraction (MVC). A 64-channel electroencephalography (EEG) cap recorded neural activity during the isometric tracings. Signals were filtered to reject artifact and compute Fast Fourier Transforms. Separate 3-way mixed factorial ANOVAs (group [BFR v non-BFR] x time [pre v post] x location [C5 v C3 v C1 v C2 v C4 v C6]) were used to compare MPF values of the beta-band at all intensities. Additional ANOVAs (group [BFR v non-BFR] x time [pre v post] x leg [right v left]) were used to compare the CZ location MPF values of the beta-band at all intensities. RESULTS: There were no significant group x time x location interactions or main effects for MPF at 25%, 50%, or 100% intensities, however there was a main effect for location at 75% (p = .045)(C5 [944.383 ± 150.647], C3 [834.815 ± 150.647], C1 [745.956 ± 150.647], C2 [1057.821 ± 150.647], C4 [1082.626 ± 150.647], C6 [1246.386 ± 150.647]; mean ± SE). When comparing group x time x leg, there was a significant interaction at 25% (p = .049) and main effect on time at 75% (p = .030)(pre [755.646 ± 126.276], post [1052.475 ± 126.276]; mean ± SE). CONCLUSION: Beta-band oscillations are often linked with various cognitive and motor functions. These results support a presence of contra-lateralization of the motor cortex with the TA during isometric contractions. President's Excellence in Research Scholars, Tarleton State University