SAT-389 Evaluation of the Hypothalamic-Pituitary-Adrenal Axis and Physical Performance in Older Adults

Abstract

INTRODUCTION: Blunting of the circadian rhythm of the hypothalamic–pituitary– adrenal (HPA) axis is known to occur with aging, although a pathological overall increase in glucocorticoid secretion is rare in elderly. Persistently high levels of cortisol are associated with increased catabolism of skeletal muscle, so that a link between chronically elevated cortisol and frailty is biologically plausible in this population. OBJECTIVE: We aimed to investigate the relationships between the activity of the HPA axis, determined the diurnal cortisol release pattern and DHEA secretion, and physical performance in older adults. METHODS: A total of 69 elderly (65.2% female), aged 60-84 years, with normal cognition and functionally healthy, with a median BMI of 27.3 kg/m2 (ranging from 19.1 to 38.6), were enrolled. Physical performance was tested by: a) number of steps per day measured by a pedometer during 3 consecutive working days; b) Sitting-Rising Test (SRT); c) Single-Leg Stance (SLS); d) Timed Up and Go (TUG); e) One-Repetition Maximum Test (1RM); f) Six Minute Walk Test (6MWT). Individuals were considered active when mean daily steps was ≥7,000 steps, and insufficiently active when <7,000 steps. Salivary cortisol (sC) was collected 30min after awakening, at 11 a.m., 5 p.m. and 9 p.m. and before bedtime in the third day of the pedometer use, and blood samples for serum DHEA concentration were collected on a subsequent day. Non-parametric Mann-Whitney test and Spearman correlation test, when applicable, were used for statistical analysis. Area under curve (AUC) was calculated for determination of the diurnal cortisol release pattern. RESULTS: A total of 41 individuals (59.4%) were classified as insufficiently active, and 28 as active (40.6%), according to pedometer-assessed steps per day. Active elderly exhibited a better balance and performance in the 1RM Test (p=0,05) than inactive. A worse performance in the 1RM Test was observed in individuals with higher sC at 11 a.m and in those with a larger AUC of sC (p<0,05). In addition, individuals with lower serum DHEA concentration exhibited a worse performance at the 6MWT (p=0.03). CONCLUSION: Our findings support the association between spontaneous physical activity levels, assessed by the pedometer daily steps measurement, and functional performance in elderly. In addition, higher diurnal cortisol secretion and lower DHEA plasmatic levels were associated with a lower physical performance in older individuals.