Journal of Applied Physiology, Vol 69, Issue 5 1607-1614, Copyright © 1990 by American Physiological Society
Exaggerated ANF response to exercise in middle-aged vs. young runners
B. J. Freund, J. R. Claybaugh, G. M. Hashiro, M. Buono and S. Chrisney
Department of Clinical Investigation, Tripler Army Medical Center, Honolulu, Hawaii 96859-5000.
Hormonal, electrolyte, and renal responses were measured before, during,
and after a marathon (42.2 km) in 14 runners: 8 young (Y) (mean age 27.8
yr) and 6 middle aged (MA) (mean aged 46.7 yr). No differences between
groups in prerun values for heart rate (HR), plasma osmolality (OSM),
antidiuretic hormone (ADH), aldosterone (ALDO), atrial natriuretic factor
(ANF), or plasma renin activity (PRA) were found. Renal and urinary
measurements were also similar between groups before the marathon. After 10
km of running, both groups had significant increases in HR, ALDO, ANF, and
PRA, while OSM, Na+, and ADH remained unchanged from prerun values. The
increase in plasma ANF concentrations at this point was significantly
greater in the MA subjects compared with the Y (mean increase 104.1 vs.
42.8 pg/ml, respectively; P less than 0.01). Immediate postmarathon values
for OSM, ADH, and Na+ were significantly higher than initial values in both
groups, while HR, PRA, and ALDO continued to increase above the elevated
levels found at 10 km. ANF values immediately postmarathon remained higher
than prerun concentrations but were significantly reduced from those
obtained at 10 km. In contrast, HR continued to rise until the completion
of the run. These data are consistent with recent reports of an exaggerated
ANF response in older subjects in response to central blood volume
expansion.
