Current evidence suggests that acute bouts of lower limb exercise elicits a number of adverse effects on both sensory and motor components of postural control. The effects of acute exercise on quiet standing balance while concurrently performing an attentional task remains equivocal. This study aimed to compare the alterations in postural control and attentional demands elicited by upper and lower limb exercise. Twelve healthy young males (mean ± SD age, 22.2 ± 3.2 years) were examined on six separate occasions. The first two visits determined maximal aerobic fitness on an arm crank ergometer (ACE) and cycle ergometer (CYC). Subsequently, participant's postural sway was assessed during single- (ST) and dual-task (DT) conditions before and immediately after moderate- and high-intensity exercise engaging the upper or lower body musculature. The order of the four exercise tests was counterbalanced. The centre of pressure displacement in the anteroposterior (COPAP) and mediolateral (COPML) directions and the COP path length (COPL) were computed using a force platform. A time × mode interaction was observed for COPAP (ST; p = 0.011, DT; p = 0.018) and COPML (ST; p = 0.001). CYC elicited large (ES; 1.6-2.0) increases in COPAP and COPML, but there were no differences between aerobic and anaerobic tests (p > 0.05). The effect of cognitive load appeared to increase sway in the frontal plane following anaerobic CYC (p = 0.001) but not ACE (p < 0.05). Exercise has different effects on frontal and sagittal plane sway following different cognitive loads. In particular, COPML was increased at the cost of maintaining attentional performance following exercise.