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Augmented leg vasoconstriction in dynamically exercising older men during acute sympathetic stimulation
Dennis W Koch1, Urs A Leuenberger, David N Proctor
1Noll Physiological Research Center, The Pennsylvania State University, University Park, PA 16801-6900, USA.
The Journal of Physiology
|June 26, 2003
Summary
Older adults show increased vasoconstrictor responsiveness during exercise, unlike at rest. This suggests age-related changes in blood vessel regulation during physical activity may differ significantly.
Area of Science:
- Physiology
- Aging Research
- Exercise Science
Background:
- Sympathetic nervous system control of blood flow is crucial for exercise.
- Age-related decline in vasoconstrictor responsiveness is observed in resting skeletal muscle.
- It remains unclear if this age-related decline extends to exercising skeletal muscle.
Purpose of the Study:
- To investigate age-related differences in sympathetic vasoconstrictor responsiveness in exercising skeletal muscle.
- To compare responses between younger and older healthy men during exercise.
Main Methods:
- Thirteen younger and seven older men performed cycle ergometer exercise.
- Leg blood flow, mean arterial blood pressure, and plasma catecholamines were measured.
- Acute sympathetic stimulation was induced using the cold pressor test (CPT).
Main Results:
- Older men exhibited a greater reduction in exercising leg vascular conductance during CPT compared to younger men.
- Increases in mean arterial blood pressure during CPT were larger in older men.
- Plasma noradrenaline responses to CPT were similar between age groups, but leg blood flow did not increase in older men.
Conclusions:
- Contrary to resting muscle, vasoconstrictor responsiveness to sympathetic stimulation appears augmented, not reduced, in exercising skeletal muscle of older adults.
- This augmented response may be due to impaired local vasodilation mechanisms, such as nitric oxide, during exercise in older individuals.