The Physiology of Stress

Our knowledge about stress and adrenal function began in the 1920s, when famous stress-research pioneer Hans Selye began to piece together the common problems resulting from excess adrenal stress. They include poor immunity and intestinal dysfunction, which in turn can trigger hundreds of other problems—like a domino effect. Selye eventually showed how the adrenals react when confronted with excess stress. This General Adaptation Syndrome has three distinct stages:

 

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  • Stage 1: The first stage begins with the alarm reaction, when we’re initially hit with a stress. This increases adrenal hormone production to help the body cope with the stress. This is what commonly occurs during anaerobic training and the competitive season, but much less during aerobic training. The purpose of this first stage by the adrenal glands is an attempt to battle and adapt to the increased stress. If it is successful, and the stress is reduced, we recover; adrenal function returns to normal, especially with sufficient rest. If this stage is of sufficient length, a variety of mild symptoms may occur: noticeable tiredness during the day, mild allergies, or even some nagging back, knee, or foot pain. If, over time—a few weeks or months—the adrenals fail to meet the needs of the body to combat the stress, they enter the second stage.
  • Stage 2: During this period, also called the resistance stage, the adrenal glands themselves get larger through a process called hypertrophy. Since the increased hormone production of the first stage couldn’t counter the stress, the glands enlarge in an attempt make even more cortisol to do the same. During this stage, more advanced symptoms may occur, including fatigue, insomnia, and more serious back, knee, or foot pain, or poor recovery. Most athletes with stress problems are stuck in this stage, often for months or years. They usually no longer see their best performances, and injuries or ill health are common. If athletes in this stage continue to push themselves, thereby maintaining high levels of stress, the adrenals eventually can enter the third stage, called exhaustion.
  • Stage 3: An athlete who enters this stage is exhausted, often with chronic injuries and most likely is not able to compete near the same level of effectiveness. The adrenal glands are unable to adapt to stress and are unable to produce adequate levels of hormones, including cortisol. The person is usually more seriously ill—physically, chemically, or mentally.

But this discussion is not just about adrenal disease; rather, it concerns the gray area between normal adrenal function and disease. Addison’s disease occurs when the adrenal glands are unable to produce sufficient cortisol to sustain life. It can occur in men and women of all age-groups; symptoms include severe weight loss, muscle weakness, fatigue, low blood pressure, and sometimes darkening of the skin. The disease is also called adrenal insufficiency or hypocortisolism.