Hormonal, electrolyte, and renal responses to exercise are intensity dependent

Abstract

Previous work indicates that the magnitude and direction of renal responses to exercise depend on the exercise intensity. To examine mechanisms responsible for these findings, renal and hormonal responses were studied in eight healthy male subjects (29.6 +/- 1.9 yr) before and immediately after four 20-min bouts of submaximal exercise (cycle ergometry) at work loads representing 25, 40, 60, and 80% of maximal oxygen consumption. Urine flow, osmotic clearance, glomerular filtration rate, and sodium excretion (UNa+V) all tended to rise at the 25% work load but were markedly reduced at the higher work intensities. Changes in urine flow paralleled changes in glomerular filtration rate (r = 0.91). Plasma vasopressin (ADH), aldosterone, and plasma renin activity tended to increase progressively with increases in work load, with the increases for all hormones reaching statistical significance when the level of exercise reached greater than or equal to 60% of maximal oxygen consumption. However, atrial natriuretic peptide was elevated (P less than 0.05) at all work loads from greater than 1.6-fold of control levels at the 25% work load to greater than 7-fold at the 80% work load. The increase in urine flow (6 of 8 subjects) and UNa+V (7 of 8 subjects) may be due to the increase in atrial natriuretic peptide and/or a 10% suppression (P less than 0.05) of ADH at the 25% work load.(ABSTRACT TRUNCATED AT 250 WORDS)

Glomerular Filtration Rate and Albumin Excretion After Maximal Exercise in Aging Sedentary and Active Men

“…They also reported that renal blood flow decreased by about 47% during exercise under these conditions. Declines in renal function during exercise are intensity-dependent (3,5,23,24) and generally in the range of 30%-60%. Our results collected on senior participants up to 80 years old extend these previous investigations obtained in young adults.…”

“…In young adults, exercise depresses renal plasma flow and glomerular filtration rates [GFRs (3)(4)(5)], and induces excretion of plasma proteins in the urine (6). Postexercise proteinuria is more specifically related to the intensity than to the duration of the exercise (7).…”

Exercise-Associated Hyponatremia

“…There are several potential pathways for stimulation of AVP release in exercising athletes. Controlled laboratory studies have demonstrated that as exercise intensity increases above 60% of maximal oxygen consumption, there are concomitant increases in AVP levels (61). Nonspecific stresses that are experienced by athletes and caused by factors such as pain, emotion, or physical exercise have been thought to cause nonosmotic release of AVP (62).…”

Estrogen effects on osmotic regulation of AVP and fluid balance

“…All blood samples were analyzed for hematocrit (Hct), hemoglobin (Hb), total protein (TP), osmolality (P Osm), plasma concentrations of creatinine (P [AVP] was determined after extraction from plasma by the methods described by Freund and colleagues (13,14) on octadecylsilane cartridges (SEP-PAK C 18; Waters Associates). Extracted samples were assayed using a disequilibrium assay with the extracts incubated with the antiserum at 4°C for 72 h, followed by the addition of 125 I-labeled AVP (New England Nuclear, Boston, MA).…”