Reduced aldosterone and sodium excretion in endurance-trained athletes before and during immersion

Abstract

Aldosterone excretion (AE) and plasma renin activity (PRA) were measured in eight untrained (UT) and eight endurance-trained (TR) male subjects before and during 4 h head-out immersion to study the mechanism of reduced renal sodium excretion in athletes. AE was significantly lower before immersion, and decreased less during immersion, in TR than in UT. Fractional sodium excretion, too, was lower and increased less during immersion in TR than in UT. PRA decreased in the water bath in all subjects (p less than 0.001) with no significant difference between the groups. During immersion, plasma sodium concentration oscillated whereas potassium concentration showed a temporary rise in TR (p less than 0.001). The attenuated response of AE in TR may be due partly to this increase of plasma potassium concentration. The generally reduced aldosterone release in TR might be caused by a training induced adaptation of the adrenals to corticotropin. The lowered renal sodium excretion of TR in spite of the decreased AE suggests an intensified aldosterone effect in these subjects, diminishing the salt loss during exercise.

Arterial Stress Hormones during Scuba Diving with Different Breathing Gases

“…The significantly increased [noradrenaline] in sample 6 (postdiving control period) only after deep submersion but not after oxygen breathing might be explained by the following mechanism. Immersion and submersion cause a blood shift to the atria; the atrial distension results in a downregulation of the renin-angiotensinaldosterone system and increased orthostatic lability (e.g., Skipka et al [24]). After leaving the water, this lability might be counteracted by an increase of noradrenaline.…”

Habitual Physical Activity, Training, and Blood Pressure in Normo- and Hypertension

“…M'Buyamba-Kabangu et al (76) found an inverse relationship between peak oxygen uptake and plasma renin activity at rest in 40 young normal subjects, and Fagard et al (32) observed a lower plasma renin in runners as compared to sedentary control subjects. Others reported a slightly but not significantly lower resting plasma renin in well-trained compared to nontrained subjects (79,116). Five months of training of normal subjects reduced plasma renin significantly (41), but 8 days did not (44).…”

Differences in Sympathoadrenal, Hormonal, and Metabolic Adaptation to Submaximal and Maximal Arm and Leg Work Compared with Whole Stroke in Breast-Style Swimming*

“…Their increase depends on duration, intensity, and training state (8,9). On the other hand, water immersion reduces PRA and PA (16,19,34). In our experiments, especially those with arm stroke, the water immersion effect was strong enough to suppress both PRA and PA acting against the stimulus of CA on PRA as well as the stimulus of ACTH and electrolyte disturbances on PA.…”