A key component of motor rehabilitation is the improvement of anticipatory postural adjustments (APAs) using tools such as the exercise ball. Concurrent cognitive tasks are often added during this rehabilitation, but their impact on APAs is unknown. This study examined the effect of concurrent cognitive tasks on anticipatory postural adjustments to voluntary movements performed while sitting on an exercise ball. Bilateral EMG activity was recorded from the external oblique, internal oblique, rectus abdominis and erector spinae muscles, as well as the right rectus femoris muscle of 20 healthy subjects (mean (SD) age of 22 (0.8) years), during rapid hip flexion movement performed in response to an auditory cue under 3 conditions: no concurrent task (QF), counting out loud up from one serially (S1s) and counting down in sevens; serial sevens task (S7s). The onset of the rise and magnitude of EMG activity in the prime mover and postural trunk muscles were measured and compared across the three conditions. The cognitive task conditions (S1s and S7s) showed a delayed response in the prime mover (40ms) after the cue to move and a reduced EMG activity (p =0.019) compared to condition with no concurrent activity, which occurred 20ms after the cue. Only the ES muscle, on the opposite side to prime mover, showed a tendency for earlier onset and higher EMG activity in the S7s task than in the S1s in the APA time window. The EO muscle on the opposite side to RF was less active in the S7s than either the S1s or the no concurrent conditions in the CPA time windows. The ES and EO muscles on the side of RF were more active during S7s than the QF condition during the CPA time windows. The RA and IO muscles showed no differences between the conditions in any APA or CPA window. The result of this study indicates that the effect of dual tasking is related to the attention demands of the cognitive task. A more demanding cognitive task results to a delayed and reduced magnitude of voluntary motor response and earlier anticipatory postural adjustments. It may be possible that dual tasking facilitates earlier postural adjustments in patients with deficient postural control, but this would need to be tested in older individuals and patients with deficient postural control.