A raft of research has proven it, and if you've been running regularly you have discovered it: running combats stress in a powerful way.
No matter how good or bad you feel at any given moment, running, most times will make you feel better. And it goes beyond just the "runner's high"—that rush of feel-good hormones known as endocannabinoids.A 2012 study in the Journal of Adolescent Health proved that just 30 minutes of running during the week for three weeks boosted sleep quality, mood, and concentration during the day.
But chronic stress—exhaustion and tension that lasts for weeks and months—can hurt your immunity, muscle function, appetite and endurance, and increase your risk for injury. Bottom line: stress can keep you from achieving your weight-loss and racing goals. Some of that impact is driven by behavior; some of it boils down to biochemistry. Here's what you need to know to keep stress from impacting your running life.
When we're stressed, our bodies perceive an imminent threat. In response, our glands release adrenalin and cortisol so we can fight or flee (hence the so-called "flight or fight response.") Cortisol tells the body to stockpile calories to contend with that threat, and to store those calories in a form that they're most likely to stick—deep within the belly.
That's why stress can rev up your appetite for sugary, fatty comfort foods—which deliver the biggest calorie punch per ounce—and why the pounds are so problematic. Visceral belly fat—which is underneath the chest and abdominal walls—and has been linked to a higher risk of diabetes and heart disease.
What's more, psychological and emotional stress will increase your risk for injury. Research has proven that stress causes distraction, increased self consciousness, and narrowing of attention that can interfere with an athlete's performance. Plus it's been shown to increased muscle tension and coordination difficulties. 
Get some sleep.
Your body needs sleep to recover from the hard work of training and bounce back quickly from tough workouts. But your body also needs sleep to keep stress levels under control. Chronic sleep deprivation has been proven to boost levels of cortisol, ghrelin (the hunger hormone), and inflammatory markers in the body.  Plus it increases your risk for chronic diseases. In addition to this hormonal disruption, "people who stay awake for long periods of time may indulge in unhealthy behaviors and eating habits," according to a 2011 study in the journal The Open Respiratory Medicine Journal. Aim for at least eight hours of sleep per day.
Given how primal the instinct is, it's only natural to want to reach for chips or chocolate when you're stressed, but resisting the temptation will pay off. Recent research suggests that stress seems to amplify the effects of junk food.In a study published in the April 2014 issue of Psychyoneuroendocrinology,researchers found that highly-stressed people who eat a lot of fatty, sugary foods,are more prone to health risks than unstressed people who eat the same food.
Research is now proving that mindfulness-based interventions for stress eating reduces both cortisol and visceral fat. A study published in the October 2011 issue of Journal of Obesity, found that simple mindful eating and stress-reduction techniques helped people prevent weight gain even without dieting. In the study, those who had the greatest reduction in stress, lost the most amount of belly fat.Mindfulness training can be used to teach people to become more aware of cues about hunger and satiety. It can also be used to develop healthier ways of responding to stress and difficult emotions.
Brightly-colored fruits and vegetables are not only good for you, but there's emerging evidence that they can help shield your body from being damaged from stress. A study published in the October 2011 issue ofHuman Psychopharmacology showed that a 90-day dosage of B-vitamins helped reduce the psychological strain that goes along with work stress. Reach for foods that are rich in B-vitamins, like dark leafy greens, avocados, eggs, and artichokes.
Immersing yourself in natural surroundings can offer more stress relief than running into the city. A study in the April 2013. issue of International Journal of Environmental Research showed that levels of cortisol (the stress hormone) were lower, while mood, and vitality were higher, in people who ran in a wooded environment, compared to those who ran in an urban setting.
 Kalak N, Gerber M, Kirov R, Mikoteit T, Yordanova J, Pühse U, Holsboer-Trachsler E. "Daily morning running for 3 weeks improved sleep and psychological functioning in healthy adolescents compared with controls." Journal of Adolescent Health. 2012 Dec;51(6):615-22.
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