Daily energy expenditure in free-living children: comparison of heart-rate monitoring with the doubly labeled water (2H2(18)O) method. - Livingstone,MB.; Coward,WA.; Prentice,AM.; Davies,PS.; Strain,JJ.; McKenna,PG.; Mahoney,CA.; White,JA.; Stewart,CM.; Kerr,MJ. (Am J Clin Nutr, 1992)