To determine if the different EEG patterns noted in previous studies were due to between-task differences in muscular exertion, the present study examined the electroencephalographic (EEG) activity in the seconds prior to either holding the weight (without lifting) or executing an arm lift at either 25% or 95% of the subject's one-repetition maximum value. Temporal EEG and tempomandibular and trapezius electromyography (EMG) measures were obtained from subjects (N=20) in the half-second period during the holding of the weight or immediately before lifting the weight. The degree of attentional focus on the task was quantified through self-report measures after each set of trials. EMG activity was not significantly different between the hold and lift phases. The self-report degree of attentional focus was higher in the lift phase, compared to the hold phase, for both 25% and 95% conditions (p<.01). Increases in EEG activity for the 25% condition were observed between the hold and lift phases at 4 Hz (p<.003). This extended to 10 additional frequencies in the 95% condition (p<.004), with beta (13 to 30 Hz) activity greater in the right hemisphere (p<.004). Because there were no EMG differences between phases or conditions» it was concluded that the EEG changes were reflective of cognitive differences associated with attending to tasks that differed in level of muscular exertion.