Eccentric, compared to concentric exercise, is proposed to involve different neuro‐motor processing strategies and a higher level of mental demand. This study compared eccentric and concentric cycling at matched perceived effort and torque for the mental demand and related‐cortical activation patterns. Nineteen men (30 ± 6 years) performed four different 5‐min cycling conditions at 30 RPM on a semi‐recumbent isokinetic cycle ergometer: (1) concentric at a moderate perceived effort (23 on the CR100® scale) without torque feedback; (2) concentric and (3) eccentric at the same average torque produced in the first condition; and (4) eccentric at the same moderate perceived effort than the first concentric condition. The conditions two to four were randomized. After each condition, mental demand was monitored using the NASA Task Load Index scale. Changes in oxy‐(O 2 Hb) and deoxy‐(HHb) hemoglobin during exercise were measured over both prefrontal cortices and the right parietal lobe from a 15‐probe layout using a continuous‐wave NIRS system. Mental demand was significantly higher during eccentric compared to concentric cycling (+52%, p = 0.012) and when the exercise intensity was fixed by the torque rather than the perceived effort (+70%, p < 0.001). For both torque‐ or perceived effort‐matched exercises, O 2 Hb increased significantly ( p < 0.001) in the left and right prefrontal cortices, and right parietal lobe, and HHb decreased in the left, and right, prefrontal cortices during eccentric compared to concentric cycling. This study supports that acute eccentric cycling, compared to concentric cycling, involves a higher mental demand, and frontoparietal network activation.