title: A 30-year follow-up of the Dallas Bedrest and Training Study: II. Effect of age on cardiovascular adaptation to exercise training.
abstract: BACKGROUND
  Aerobic power declines with age. The degree to which this decline is reversible remains unclear. In a 30-year longitudinal follow-up study, the cardiovascular adaptations to exercise training in 5 middle-aged men previously trained in 1966 were evaluated to assess the degree to which the age-associated decline in aerobic power is attributable to deconditioning and to gain insight into the specific mechanisms involved. Methods and Results-- The cardiovascular response to acute submaximal and maximal exercise were assessed before and after a 6-month endurance training program. On average, VO(2max) increased 14% (2.9 versus 3.3 L/min), achieving the level observed at the baseline evaluations 30 years before. Likewise, VO(2max) increased 16% when indexed to total body mass (31 versus 36 mL/kg per minute) or fat-free mass (44 versus 51 mL/kg fat-free mass per minute). Maximal heart rate declined (181 versus 171 beats/min) and maximal stroke volume increased (121 versus 129 mL) after training, with no change in maximal cardiac output (21.4 versus 21.7 L/min); submaximal heart rates also declined to a similar degree. Maximal AVDO(2) increased by 10% (13.8 versus 15.2 vol%) and accounted for the entire improvement of aerobic power associated with training.
  
  
  CONCLUSIONS
  One hundred percent of the age-related decline in aerobic power among these 5 middle-aged men occurring over 30 years was reversed by a 6-month endurance training program. However, no subject achieved the same maximal VO(2) attained after training 30 years earlier, despite a similar relative training load. The improved aerobic power after training was primarily the result of peripheral adaptation, with no effective improvement in maximal oxygen delivery.
authors.affiliation: Pauline and Adolph Weinberger Laboratory for Cardiopulmonary Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-9047, USA. darren.mcguire@utsouthwestern.edu
authors.forename: D K
authors.initials: DK
authors.lastname: McGuire
authors.forename: B D
authors.initials: BD
authors.lastname: Levine
authors.forename: J W
authors.initials: JW
authors.lastname: Williamson
authors.forename: P G
authors.initials: PG
authors.lastname: Snell
authors.forename: C G
authors.initials: CG
authors.lastname: Blomqvist
authors.forename: B
authors.initials: B
authors.lastname: Saltin
authors.forename: J H
authors.initials: JH
authors.lastname: Mitchell
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000273:Adipose Tissue / Q000502:physiology; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D001510:Bed Rest; D001835:Body Weight / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D018493:Cardiovascular Deconditioning / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology; D013995:Time; D014655:Vascular Resistance / Q000502:physiology