The aim of this observational study was to compare head motion and prefrontalhaemodynamics during exercise using three commercial cycling ergometers. Participants (n=12) completed an incremental exercise test to exhaustion duringupright, recumbent and semi-recumbent cycling. Head motion (using accelerometry), physiological data (oxygen uptake, end-tidal carbon dioxide [PETCO2] andheart rate) and changes in prefrontal haemodynamics (oxygenation, deoxygenation and blood volume using near infrared spectroscopy [NIRS]) were recorded.Despite no difference in oxygen uptake and heart rate, head motion was higherand PETCO2was lower during upright cycling at maximal exercise (P<005). Analyses of covariance (covariates: head motionP>005; PETCO2,P<001) revealed that prefrontal oxygenation was higher during semi-recumbent than recumbentcycling and deoxygenation and blood volume were higher during upright than recumbent and semi-recumbent cycling (respectively;P<005). This work highlights the robustness of the utility of NIRS to head motion and describes the potential postural effects upon the prefrontal haemodynamic response duringupright and recumbent cycling exercise.