Human Competition and Stress

Hormonal Responses to Stress

Stress can be defined as a physical and/or psychological response to life experiences that may challenge or threaten us. Furthermore, stress can be experienced both subjectively through anxiety, fear, anger, and depression as well as physiologically. Stress can be brought on by several negative life events, such as a death in the family, divorce, or relocation, or even positive events such as a big job promotion or winning the lottery. When faced with a stressful situation, the body activates the sympathetic nervous system, which through the hypothalamus-pituitary-adrenal (HPA) axis mediates a wide range of adaptive functions. The stress response first begins in a deep structure within the brain known as the hypothalamus. The hypothalamus releases a protein known as the corticotopin-releasing factor (CRF), which then stimulates the pituitary gland. The pituitary gland then releases adrenocorticotropin hormone (ACTH), which, in turn, stimulates the release of cortisol from the adrenal gland. One way to measure HPA axis activation is by assessing cortisol levels. Cortisol has been found to be the most accepted marker of HPA axis activation. Furthermore, increased cortisol has been known to be an adaptive mechanism of the organism when stressed. Moderate increases in cortisol are known to prepare individuals for immediate or forthcoming action. This moderate increase enables one's blood to move from the extremities to the large muscles that are used in physical activity, and it has also been shown to play a positive role in cognition and emotions. In contrast, larger increases in cortisol have been shown to decrease performance by interfering with cognitive processes and also by lowering testosterone levels. Furthermore, chronic stress has been shown to have a significant negative effect on one's immune system.

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