How Exercise Impacts Stress Hormones and Blood Sugar Levels
My Twitter friend @LolaMcIntyre brought to my attention her blood sugar goes up when she's stressed. I tweeted her, it's "because cortisol (stress hormone) increases when stressed". She wanted to know more, the answers were too long to fit in 140 characters, so here's the post.
Stress Impacts You Physically
Physical and emotional stress set off a cascade of events mediated through nerve impulses as well as secretion of hormones in the blood and brain.
When you encounter stress, your nerves send a signal to your brain, "stress"; these impulses are transferred within the brain to the pituitary gland, part of the brain that controls your endocrine (hormone) glands. Through nerve signals and secretion of hormones your pituitary gland sparks the adrenal gland ("Hey, adrenals, we've got some 'stress' here!").
The adrenals make cortisol which affects your blood vessels, blood sugar, and other facets of metabolism.
In addition to "turning on" the adrenals via the pituitary gland, the brain also sends nerve signals via the sympathetic nervous system to increase your heart rate, breathing, and blood pressure.
Stress affects you physically: if you're diabetic, it increases your blood sugar by increasing cortisol; if you have heart disease, stress can induce chest pain by triggering blood vessel spasm.
So how do we effectively relieve/prevent stress?
Exercise.
Exercise is as or more effective than blood pressure medicines, diabetes medications, and anxiety medications, at relieving and modulating the physical effects of stress.
What Kind of Exercise?
Morning yoga affects not only blood sugar throughout the day, but perception of stress, heart rate and other factors impacting cardiovascular health.
Actually any exercise does this but I choose yoga because it's easy on the body first thing in the morning (compared to running or lifting weights) and it can be done in any weather (i.e. indoors). Yoga does not require any special equipment.
Yoga is flexible (pun intended): it can be as meditative or as aerobic as you want to make it (e.g. Shiva Rae's DVD's on flow yoga; I recommend "Flow Yoga for Beginners" also available on Amazon).
The following facts apply to exercise done at any time of the day, but I focus on yoga because it has all the benefits of more "vigorous" exercise but has a low barrier to initiating activity, and is easy on the joints, especially in the morning. Yoga and walking are my two favorite exercises for stress relief and conditioning.
Blood Sugar Levels
Morning exercise favorably increases all markers of insulin resistance, also known as glucose intolerance, diabetes, and pre-diabetes. Depending on consistency and duration (from 6 wks to 12 months), yoga has been shown to:
Decrease fasting blood sugar by 5.4 to 33.4%
Decrease post-prandial (after meal) blood sugar by 24-27%
Decrease glycosylated hemoglobin (HgbA1c) by 13-27%
Blood Lipid Levels (cholesterol, etc.)
Yoga:
Decreases Total cholesterol by 5-25%
Decreases LDL ('bad") cholesterol by 12-26%
Increases HDL ("good") cholesterol
Decreases Triglycerides ("bad"--diabetogenic) by 22-25%
Body Signs of Stress
Yoga:
Decreases heart rate 4-38%
Decreases respiratory rate 4-60%
Decreases diastolic blood pressure by 5-24%
Decreases systolic blood pressure by 2.6-21%
Stress Hormones in the Bloodstream
Yoga:
Decreases epinephrine and norepinephrine levels (adrenaline and noradrenaline, the major stress hormones produced by the adrenal glands)
Decreases cortisol (produced by the adrenals; regulates blood sugar in response to stress)
Decreases cardiovascular reactivity to stress (i.e. you get less elevation in heart rate and blood pressure in response to stress if you do yoga 3x/wk).
Increases heart rate variability (a measure of how well the heart responds to stress).
Decreases 6 AM cortisol levels, thereby decreasing cortisol throughout the day, and decreasing blood sugar throughout the day.
Impact on Cardiovascular Disease and Need for Interventions
Yoga:
Decreases the need for medications for diabetes and hypertension (high blood pressure)
Decreases carotid artery media intimal thickness (atherosclerosis of the arteries supplying the brain)--a predictor of stroke)
Decreases angina
Decreases serious coronary events
Decreases the need for hospitalization for cardiac problems
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