Stress Reactivity to Repeated Low-Level Challenges: A Pilot Study

Abstract

The purpose of this study was to examine the effects of a mental challenge on cardiovascular and endocrine [epinephrine (EPI), norepinephrine (NE), and cortisol (CORT)] responses to subsequent low-intensity physical exertion. Twelve males (23.25±0.45 years) completed three sessions, including a graded exercise test on a cycle ergometer and two counter-balanced mental stress trials. In the mental challenge-control condition (MC), participants sat quietly for 20 min following a 20 min mental challenge whereas in the mental challenge-exercise condition (MEC) subjects cycled at 35% of maximal oxygen consumption (VO2max) following the mental challenge. Repeated-measures ANOVAs were used to assess state anxiety (SAI), cardiovascular variables, EPI, NE, and CORT levels across time between conditions. Participants reported significantly greater increases in SAI scores immediately after the mental challenge, which then decreased post-challenge in both conditions. Neither EPI or NE demonstrated an alteration in levels in either condition, but CORT significantly increased after the mental challenge in both conditions and then maintained a significantly greater level during the MEC compared to the MC condition from midexercise through 15 min of recovery. Area-under-the-curve calculations for CORT was significantly greater in the MEC compared to the MC. Results suggest that the initial mental challenge may have acted to enhance the overall adrenal response to the subsequent anticipation of and actual participation in the low-level physical challenge.

Effect of Exercise with Mental Stress on Cortisol and Alpha-Amylase Changes in Young Men

“…The alpha-amylase assay in the saliva is a noninvasive method of measuring SAA axis activity (21). SAA and HPA axis activity generally influences cardiovascular and metabolic functions in response to different stressors (22). In the present study, the results showed no significant difference in cortisol changes between exercise train- ing and exercise training with mental stress groups as an indicator of HPA axis activity although there was an increase in the parameters of both groups in the posttest compared to the pretest.…”

Aerobic Fitness Affects Cortisol Responses to Concurrent Challenges

“…Furthermore, it has been suggested that the HPA axis is not particularly sensitive to the effects of MA or SCW (7) and that tasks that are perceived as uncontrollable with a social-evaluative threat such as public speaking (13) are more effective in stimulating the HPA axis. However, previous studies have demonstrated that the Stressor used in this study is effective in stimulating an HPA axis response (22,37,39).…”

Exogenous Carbohydrate Reduces Cortisol Response from Combined Mental and Physical Stress

“…Physical stress (i.e., exercise at or above 80 % VO 2 peak) is known to induce a significant response from the HPA axis [17]. The combination of mental and physical stress may result in potentially dangerous cardiovascular responses (e.g., exacerbated CORT production) even when physical stress is less than 80 % VO 2 peak [39,40,42]. In addition, prolonged low-intensity physical exercise stimulates the HPA axis and induces adrenocorticotropic hormone (ACTH) and CORT secretion [35][36][37].…”

“…While the acute secretion of CORT during exercise and in response to stress is highly beneficial for metabolic function, excessive and chronic hypercortisolemia that is seen with combined mental and physical stress can be problematic for indivdiuals chronically exposed to such occupational conditions. Chronic elevations in CORT is associated with via oxidative stress, hyperlipidemia [21], in addition to impaired vascular functioning and increased platelet aggregation [39] which may facilitate atherogenesis [10,22]. These findings may serve as a potential mechanism for the increased prevalence of CVD among high stress occupations such as firefighters [20,21,25,32].…”

“…[ [39][40][41]. One study reported that beverages containing CHO and caffeine may be effective at reducing anxiety and perceived stress during fire-fighter activities [36,4].…”