Attenuated exercise induced hyperaemia with age: mechanistic insight from passive limb movement.
The influence of age on the central and peripheral contributors to exercise-induced hyperaemia is unclear. Utilizing a reductionist approach, we compared the peripheral and central haemodynamic responses to passive limb movement (exercise without an increase in metabolism) in 11 old (71 ± 9 years of age S.D.) and 11 young (24 ± 2 years of age) healthy subjects. Cardiac output (CO), heart rate (HR), stroke volume (SV), mean arterial pressure (MAP), and femoral blood flow of the passively moved and control legs were evaluated second-by-second during 2 min of passive knee extension at a rate of 1 Hz. Compared to the young, the old group exhibited a significantly attenuated increase in HR (7 ± 4% vs. 13 ± 7% S.D.), CO (10 ± 6% vs. 18 ± 8%) and femoral blood flow in the passively moved (123 ± 55% vs. 194 ± 57%) and control legs (47 ± 43% vs. 77 ± 96%). In addition, the change in vascular conductance in the passively moving limb was also significantly attenuated in the old (2.4 ± 1.2 ml min(-1) mmHg(-1)) compared to the young (4.3 ± 1.7 ml min(-1) mmHg(-1)). In both groups all main central and peripheral changes that occurred at the onset of passive knee extension were transient, lasting only 45 s. In a paradigm where metabolism does not play a role, these data reveal that both central and peripheral haemodynamic mechanisms are likely to be responsible for the 30% reduction in exercise-induced hyperaemia with age.
McDaniel
John
J
George E. Whalen VA Medical Center, Salt Lake City, Utah 84148, USA. John.McDaniel@utah.edu
Hayman
Melissa A
MA
Ives
Steve
S
Fjeldstad
Anette S
AS
Trinity
Joel D
JD
Wray
D Walter
DW
Richardson
Russell S
RS
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005121:Extremities / Q000098:blood supply / Q000502:physiology; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology*; D007866:Leg / Q000098:blood supply / Q000502:physiology*; D008297:Male; D015915:Motion Therapy, Continuous Passive / Q000379:methods; D009068:Movement / Q000502:physiology*; D055815:Young Adult