Abstract
The hemodynamic effects of exercise during short-term exposure to a cold, hot and comfortable environment were studied in normal subjects. Seven untrained males (19 to 34 years) exercised on a bicycle while exposed to temperatures of 7 °C, 22 °C and 41 °C inside an environmental chamber. Values for oxygen consumption (VO2), pulmonary capillary blood flow (Qc), pulmonary capillary and tissue volume (V(t+c)) and pulmonary diffusing capacity for CO (DL) were obtained using a non-invasive rebreathing technique. These parameters and heart rate (HR) were measured after 15 min of sitting exposure and during three episodes of exercise (50, 75 and 100 W) for 5 min each. Resting VO2 at 7 °C was 31% higher than at 22 °C (p < 0.01) and 43% higher than at 41 °C (p < 0.05). During exercise, VO2 increased independently of temperature. While all measured hemodynamic parameters were similar during exercise at 7 °C and 22 °C, HR was consistently higher and stroke index lower during exercise at 41 °C. At 95% of maximum heart rate (HRmax.) at 41 °C, Qc was 13% lower than at 22 °C (p < 0.01) and 14% lower than at 7 °C (p < 0.05). V(t+c) and DL increased during exercise and were not affected by temperature. In normal man: 1) central hemodynamic changes at rest are more pronounced during short-term cold than during similar heat exposure; 2) VO2 during moderate and severe exercise is independent of ambient temperature; 3) Qc near HRmax. is decreased in hot environment; and 4) exercise induced increases in DL and V(t+c)/kg appear to be independent of ambient temperature.
| Original language | English |
|---|---|
| Pages (from-to) | 429-441 |
| Number of pages | 13 |
| Journal | Clinical Respiratory Physiology |
| Volume | 16 |
| Issue number | 4 |
| State | Published - Dec 1 1980 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
Cite this
Hemodynamics at rest and during exercise in comfortable, hot and cold environments.Measurement with a rebreathing technique. / Küng, M.; Tachmes, L.; Birch, S. J.; Fernandez, R. J.; Abraham, W. M.; Sackner, M. A.
In: Clinical Respiratory Physiology, Vol. 16, No. 4, 01.12.1980, p. 429-441.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Hemodynamics at rest and during exercise in comfortable, hot and cold environments.Measurement with a rebreathing technique
AU - Küng, M.
AU - Tachmes, L.
AU - Birch, S. J.
AU - Fernandez, R. J.
AU - Abraham, W. M.
AU - Sackner, M. A.
PY - 1980/12/1
Y1 - 1980/12/1
N2 - The hemodynamic effects of exercise during short-term exposure to a cold, hot and comfortable environment were studied in normal subjects. Seven untrained males (19 to 34 years) exercised on a bicycle while exposed to temperatures of 7 °C, 22 °C and 41 °C inside an environmental chamber. Values for oxygen consumption (VO2), pulmonary capillary blood flow (Qc), pulmonary capillary and tissue volume (V(t+c)) and pulmonary diffusing capacity for CO (DL) were obtained using a non-invasive rebreathing technique. These parameters and heart rate (HR) were measured after 15 min of sitting exposure and during three episodes of exercise (50, 75 and 100 W) for 5 min each. Resting VO2 at 7 °C was 31% higher than at 22 °C (p < 0.01) and 43% higher than at 41 °C (p < 0.05). During exercise, VO2 increased independently of temperature. While all measured hemodynamic parameters were similar during exercise at 7 °C and 22 °C, HR was consistently higher and stroke index lower during exercise at 41 °C. At 95% of maximum heart rate (HRmax.) at 41 °C, Qc was 13% lower than at 22 °C (p < 0.01) and 14% lower than at 7 °C (p < 0.05). V(t+c) and DL increased during exercise and were not affected by temperature. In normal man: 1) central hemodynamic changes at rest are more pronounced during short-term cold than during similar heat exposure; 2) VO2 during moderate and severe exercise is independent of ambient temperature; 3) Qc near HRmax. is decreased in hot environment; and 4) exercise induced increases in DL and V(t+c)/kg appear to be independent of ambient temperature.
AB - The hemodynamic effects of exercise during short-term exposure to a cold, hot and comfortable environment were studied in normal subjects. Seven untrained males (19 to 34 years) exercised on a bicycle while exposed to temperatures of 7 °C, 22 °C and 41 °C inside an environmental chamber. Values for oxygen consumption (VO2), pulmonary capillary blood flow (Qc), pulmonary capillary and tissue volume (V(t+c)) and pulmonary diffusing capacity for CO (DL) were obtained using a non-invasive rebreathing technique. These parameters and heart rate (HR) were measured after 15 min of sitting exposure and during three episodes of exercise (50, 75 and 100 W) for 5 min each. Resting VO2 at 7 °C was 31% higher than at 22 °C (p < 0.01) and 43% higher than at 41 °C (p < 0.05). During exercise, VO2 increased independently of temperature. While all measured hemodynamic parameters were similar during exercise at 7 °C and 22 °C, HR was consistently higher and stroke index lower during exercise at 41 °C. At 95% of maximum heart rate (HRmax.) at 41 °C, Qc was 13% lower than at 22 °C (p < 0.01) and 14% lower than at 7 °C (p < 0.05). V(t+c) and DL increased during exercise and were not affected by temperature. In normal man: 1) central hemodynamic changes at rest are more pronounced during short-term cold than during similar heat exposure; 2) VO2 during moderate and severe exercise is independent of ambient temperature; 3) Qc near HRmax. is decreased in hot environment; and 4) exercise induced increases in DL and V(t+c)/kg appear to be independent of ambient temperature.
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M3 - Article
VL - 16
SP - 429
EP - 441
JO - Clinical Respiratory Physiology
JF - Clinical Respiratory Physiology
SN - 0272-7587
IS - 4
ER -