CELENTANO, F., G. CORTILI, P. E. DI PRAMPERO, AND P. CERRETELLI. Mechanical aspects of rowing. J. Appl. Physiol. 36(6): 642-647. 1974.-A simplified theoretical analysis of the oar movement as a consequence of the applied external forces has been made. This allows the interpretation of the measurements of axial and transverse forces acting on the oarlock pin. Resistance to progression increases with the square of the mean speed. The ratio between transverse and axial force, the latter being the component actually useful for progression, is 0.22, instead of the maximal theoretical value of 0.11, indicating that the rowing performance can, theoretically, be improved. At a given mean speed the work required to cover a given distance decreases slightly with decreasing the speed oscillation at each stroke. It is therefore convenient to increase the rowing frequency, within the limits set by the efficiency of muscular contraction.