Influence of fitness on the integrated neuroendocrine response to aerobic exercise until exhaustion

Abstract

A group of trained and sedentary men performed an incremental graded exercise-test to exhaustion in order to assess the organic response of the two main stress-activated systems: the sympathetic nervous system with its endocrine component (the adrenal medulla), and the hypothalamic-pituitary-adrenal (HPA) axis. Maximal plasma concentrations of ACTH, cortisol and endogenous opioids (beta-endorphins) were obtained at the end of the exercise-test in the trained group. Thus ACTH increased from basal value of 21.25 +/- 2.5 pg/ml to 88.78 +/- 11.8 pg/ml at the end of the exercise (p<0.01); cortisol, from 16.56 microg/dl +/- 4.94 microg/dl to 23.80 +/- 4.57 microg/dl in min 15 of the recovery period (p<0.001); and beta-endorphin from 21.80 +/- 8.33 pmol/ml to 64.36 +/- 9.8 pmol/ml in min 3 of the recovery period (p<0.05). Catecholamine levels were increased from initial values at the end of the effort test in both control and trained groups. Control subjects exhibited a higher responsiveness compared to trained and showed superior intrinsic stimulation of the sympathetic nervous system. These results reveal a different response according to fitness in a physical stress situation.

Fitness Level Moderates Executive Control Disruption During Exercise Regardless of Age

“…Potential methodological confounds such as the type of cognitive task (executive vs. nonexecutive), fitness level (lower vs. higher fit), and age (younger vs. older adults) were taken into account. Our hypotheses were that executive components of the task that relies on the integrity of the frontal lobes would show greater impairment than nonexecutive conditions (Dietrich, 2006;Dietrich & Audiffren, 2011;Labelle et al, 2013), that this phenomenon would be more pronounced at heavier workloads (Dietrich, 2006;Labelle et al, 2013;McMorris, 2009), and that this would be true especially for lower-fit individuals (Brisswalter, Arcelin, Audiffren, & Delignieres, 1997;de Diego Acosta et al, 2001;Labelle et al, 2013;McMorris, 2009). Although very few studies have assessed the influence of acute exercise on cognition of older adults, it was suggested that older adults could show poorer cognitive results than younger adults, especially in tasks relying heavily on the frontal lobes (i.e., executive control conditions), considering age-related deficit in frontal lobe function and executive control as well as age-related VO 2 max decline.…”

“…These results are also in line with the cardiovascular fitness hypothesis as the deleterious effect of increasing intensity from 60 to 80% PPO in this condition was only shown in lower-fit individuals. A steeper decrease in blood O 2 saturation and/or metabolites in the frontal lobe regions (Rooks et al, 2010) or an important increase in catecholamine concentrations (de Diego Acosta et al, 2001) could be potential etiologies of this phenomenon. As mentioned previously, it is possible that the greater task complexity of the inhibition nonswitch trials compared with inhibition trials alone might explain why effects were only seen in these trials and not the other ones.…”

Effects of Exhaustion and Calcium Supplementation on Adrenocorticotropic Hormone and Cortisol Levels in Athletes

“…It was stated that this increase was due to activation of hypophysis and adreno-cortical axes by stress derived from intense physical activity [19]. Other studies deal with cases of altered and dysfunctional hypothalamic-pituitary axis [20,21] and with hormonal changes due to training under different conditions [22][23][24][25][26].…”

Effect of Plasmapheresis on Serum Beta-Endorphin Levels

“…Presumably, treatment releases the ligands from opioid receptors and thereby increases BE level. Stress itself is a known inducer of BE release like hot stress [9] or exercise stress [10] which, in turn, may have an inhibitory effect on immune functions [11] . A large quantity of BE is stored in memory T cells.…”