Related Experiment Videos
Age alters the cardiovascular response to direct passive heating
C T Minson1, S L Wladkowski, A F Cardell
1Noll Physiological Research Center, Pennsylvania State University, University Park, Pennsylvania 16802-6900, USA.
Summary
Older men exhibit reduced skin blood flow during heat stress due to lower cardiac output and less blood redistribution from internal organs. This age-related decline impacts the body's ability to cool effectively.
Area of Science:
- Physiology
- Thermoregulation
- Aging Research
Background:
- Direct passive heating increases skin blood flow via cardiac output and splanchnic/renal redistribution in young men.
- Age-related differences in cardiovascular and vascular responses to heat stress are not fully understood.
Purpose of the Study:
- To investigate the impact of age on cardiovascular and vascular adaptations during passive heating.
- To compare the responses of young and older men to thermal limit tolerance.
Main Methods:
- Seven young (23 yrs) and seven older (70 yrs) men underwent passive heating using water-perfused suits.
- Measurements included cardiac output, heart rate, blood pressures, skin blood flow, splanchnic blood flow, renal blood flow, and temperatures.
Main Results:
- Older men had significantly lower cardiac output (7.4 L/min vs 11.1 L/min) at thermal limit.
- Lower stroke volume in older men was the primary cause of reduced cardiac output.
- Older men showed less blood flow redistribution from splanchnic and renal circulations (720 ml/min vs 960 ml/min).
Conclusions:
- Age attenuates the increase in cardiac output and vascular redistribution necessary for adequate skin blood flow during passive heating.
- Older adults have a diminished capacity to increase skin blood flow, potentially impairing heat dissipation.