Continuum of cardiovascular performance across a broad range of fitness levels in healthy older men. - Schulman,S.P.; Fleg,J.L.; Goldberg,A.P.; Busby-Whitehead,J.; Hagberg,J.M.; O'Connor,F.C.; Gerstenblith,G.; Becker,L.C.; Katzel,L.I.; Lakatta,L.E.; Lakatta,E.G. (Circulation, 1996)