ACSM position stand on the recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in adults. - Pollock,M.; Gaesser,G.A.; Butcher,J.D.; Depres,J.P.; Dishman,J.K.; Franklin,B.A.; Garber,C.E. (Med Sci Sports Exerc, 1998)