Hypothalamic-pituitary-adrenal (HPAA) and -gonadal (HPGA) axis modification and cognitive
impairments have been reported in elderly subjects and related to physical training
status. The aim of this study was to investigate if HPAA and HPGA regulation are altered
in elderly distance runners (RUNI; n = 8; age: 68.9 ± 4.2 yrs; training: 65±20km/wk
over the last 20yrs; means ± SD) or are affected in elderly sedentary indiividuals
(SED; n = 11; age: 69.1 ± 2.6yrs) by an aerobic training over 20 weeks (3 times/week,
30-60 min walking), respectively. The protocol included assessment of the hormone
profile iin basal non-suppressed state as well as evaluation of hormonal [responses
to dexamethasone (DEX, 1.5 mg) induced adrenal suppression, to post-DEX combined corticotrophin
releasing hormone (CRH; 0.7μg/kg) and luteinizing hormone releasing hormone (LHRH,
0.7μg/kg) stimulation and to exercise challenge (30 min cycle ergometry at 65 % V02max).
Mental functions influenced by HPAA and HPGA activity were also assessed in RUN aind
SED before (SED-PRE) and after (SED-POST) the training program. Basal and post-DEX
plasma concentrations of adrenocorticotropic hormone (ACTH), Cortisol (CSL), luteinizing
hormome (LH), follicle stimulating hormone (FSH) and testosterone (T) did not differ
between RUN and SED-PRE. Basal plasma free T concentration was significantly lower
in RUN (RUN: 10.23 ± 2.41 pg · ml-1 vs. SED-PRE: 16.6 ± 5.59 pg · ml-1). During releasing hormone challenge test after DEX administration (DEX/RH), no differences.
were found between RUN and SED-PRE in plasma ACTH, LH, FSH and T response. During
this stimulation test, plasima CSL was significantly higher in RUN than in SED-PRE
after 90min (RUN: 5.86 ± 3.65 μg · dl-1 vs. SED-PRE: 2.74 ± 2.09 μg · dl-1). Differences in plasma CSL concentrations between groups w/ere not induced by 30-min
exercise challenge. Basal hormone profile was not altered by training in SED. During
DEX/RH only plasma
ACTH concentration was significantly higher in SED-POST compared to SED-PRE. Long
and short-term memory function did not differ between RUN, SED-PRE and SED-POST. Our
data suggest that following post-DEX CRH/LHRH challenge elderly endurance athletes
reveal-in the absence of altered peak values-a pattern of prolonged secretion of glucocorticoids.
However, the high interindividual variability of plasma ACTH and CSL concentrations
shows that reduced corticotropic sensitivity to negative feedback is not always induced
by chronic exercise stress. Lower plasma free T concentrations in RUN compared to
SED are not caused by modified LH synthesis-secretion capacity.
Key words
Aging - dexamethasone - releasing hormones - reproductive system - training
