Cardiac adrenergic preponderance due to lack of physical exercise and its pathogenic implications∗

The results reveal a linear increase of cardiac sympathetic tone and decline of cardiac neurovegetative counterregulatory effectiveness in proportion to decreasing degrees of habitual exercise.

Abstract

The influence of habitual vigorous exercise and of the lack of it, respectively, on the basic cardiac neurovegetative status at rest was studied in 360 healthy American and Austrian men (seventeen to fifty years of age), ranging from competitive athletes, mountaineers and Alpine soldiers to completely sedentary persons. Heart rate and the dynamic cardiac cycle (chronodynogram) at rest with special consideration of the isometric period of the left ventricle (total systole minus ejection period) were used as criteria of cholinergic, sympatho-inhibitory and adrenergic chronotropic and inotropic influences, respectively. In 216 subjects, the effects of vagal elimination (atropinization), in seventy-five the effects of infused epinephrine, and in sixty-four of norepinephrine, before and after atropinization, were recorded. The results, especially the basic resting values, reveal a linear increase of cardiac sympathetic tone and decline of cardiac neurovegetative counterregulatory effectiveness in proportion to decreasing degrees of habitual exercise. Physical training periods reversed the situation. Smoking habits (ranging from non-smoking to heavy smoking) seemed to leave the basic cardiac neurovegetative status unaltered despite the immediate adrenergic cardiac effects of tobacco smoking. The cardiovascular metabolic and functional hazards of physical inactivity-induced potentially oxygen-wasting, cardiac efficiency-impairing, myocardium-damaging and possibly atherogenesis-promoting adrenergic overactivity are discussed. Expanded epidemiological studies of primary neurovegetative factors together with other correlated pathogenic conditions (dietary, social, emotional), and the development of medically supervised, prophylactic mass reconditioning programs for degenerating sedentary populations are being urged.