Why the study?
Does physical training influence the adjustment of myocardial blood flow, oxygen consumption, and substrate uptake to acute arterial hypoxia in healthy individuals?
Does physical training influence the adjustment of myocardial blood flow, oxygen consumption, and substrate uptake to acute arterial hypoxia in healthy individuals?
Physical training lowers baseline myocardial oxygen consumption but does not alter the regulatory response of myocardial blood flow and metabolism to acute hypoxia.
Training lowers baseline myocardial metabolism without altering hypoxic regulation; leaves open clinical relevance in disease or ischemia.
To determine whether adjustment of myocardial blood flow (MBF), myocardial oxygen consumption (MVO 2 ) and myocardial substrate uptake (MSU) to acute arterial hypoxia is influenced by training effects on the heart, 7 trained and 7 untrained healthy individuals were investigated. MBF (argon method), MVO 2 and MSU of glucose, lactate and free fatty acids were measured at rest during normoxia and two different stages of acute arterial hypoxia: a) 12.82 vol% O 2 ; b) 8.74 vol% O 2 . Measurements were carried out during hemodynamic and respiratory steady state conditions. Myocardial flow and metabolism of athletes were significantly (p<0.01) lower compared to untrained subjects. In the trained cohort, MBF increased from 65 ± 19 to 73 ± 16 (a) and 98 ± 23 (b) ml/min·100 g. MVO 2 remained at normoxic control level of 8.00 ± 2.27 ml/min·100g. In the untrained group, MBF increased from 77 ± 15 to 84 ± 20 (a) and 108 ± 18 (b) ml/min · 100g. Again, there was no significant deviation in MVO 2 from the normoxic level of 10.11 ± 1.90 ml/min·100g. Decrease in arterial oxygen content was overcompensated by an increase in coronary conductance resulting in a significantly improved efficiency of myocardial perfusion during severe hypoxia. MSU of glucose, lactate and free fatty acids as well as calculated ATP production did not change significantly during hypoxia. It is concluded that training effects on the heart do not influence regulation of MBF, MVO 2 and MSU during moderate or severe acute arterial hypoxia. Reaction of coronary smooth muscle tone to a decrease in oxygen partial pressure is independent from training effects. However, both acute arterial hypoxia and physical training exert synergetic effects on the heart by reducing myocardial oxygen consumption per heart beat. Thus, it is assumed that adaptive properties of myocardial blood flow and metaboüsm to severe hypoxia are more pronounced in trained than in untrained individuals.
No takes yet. Share an insight, caveat, or question.
Heiss et al. (1978) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: