We measured Cz electroencephalogram (EEG) and tibialis anterior (TA) electromyogram (EMG) during a 60-second isometric contraction with dorsiflexion of the right ankle joint. Then we examined the motor control of TA by analyzing the changes in β- and γ-band integrated coherence (β-COH, γ-COH), EEG power (β-EEG, γ-EEG), EMG power (β-EMG, γ-EMG), EMG mean frequency (MNF), and EMG root mean square (RMS) with increasing contractile force. As a result of investigating the large and small β-COH groups (COH+ and COH− groups, respectively), there were significant differences in γ-COH, β-EMG, γ-EMG, MNF, and RMS among contractile forces in both COH+ and COH− groups. These results suggest that γ-COH is more strongly involved in maintaining movement associated with increasing contraction force than β-COH. On the other hand, γ-COH showed a significant increase with increasing contractile force in both COH+ and COH− groups. However, the rate of increase was different between each group. These results suggest that the COH− group exerts the same motor control as the COH+ group accompanying with compensation control of the COH− group own.