Experts know that exercise reduces anxiety and symptoms of depression, elevates mood, and enhances stress resiliency. As such, they are exploring its potential for both the prevention and treatment of post-traumatic stress disorder (PTSD).
A recent study published in Medicine & Science in Sports & Exercise looked specifically at the effect of exercising before a traumatic experience on the prevalence of symptoms associated with PTSD.
In the study, rats were divided into an exercise group, a sedentary group, and a control group. The exercisers ran on a treadmill five days a week for six weeks, gradually working up to 20 minutes per session.
After six weeks, both the exercise and sedentary rats were exposed to a predator scent to mimic a traumatic event—they were placed for 10 minutes on used (but sifted for stool) cat litter. The control animals were placed on clean, scent-free litter.
After seven days, the animals were tested to determine if they exhibited any lasting behavioral changes from the cat-scent exposure. Investigators measured their performance in a maze—how long the animals spent in open-air areas versus how long they stayed in the tunnel-like stretches, the idea being if you’re a highly anxious rat, you’re going to avoid any areas where, say, a hawk or a cat could spot you.
They then exposed the animals to a series of loud sounds. They measured the average degree to which each rat was startled and how habituated it became to those sounds over time. Again, if you’re in a highly anxious state, loud sounds are pretty much always scary, and it’s hard to recognize that the sound is not actually a threat. Loud and annoying, yes; harbinger of doom, no.
The investigators found that, compared to the animals that exercised and to the controls, sedentary rats performed worse in the maze and the startle tests—they hid more and explored less while in the maze, and they startled more severely at the loud sounds. In short, the sedentary group showed a significantly higher incidence of extreme behaviors consistent with PTSD.
So why were the active rats so resilient?
It may be due to the presence of three markers in the brain associated with the hippocampus, the area of the brain that is particularly sensitive to stress.
These markers—brain derived neurotrophic factor (BDNF), neuropeptide Y (NPY), and delta opioid receptor (DOR)—are responsible for neuron health, our emotional response to stress, and our sense of well-being, respectively. Having more of all of these markers is better in terms of how well you bounce back from stress. Studies have shown that some of these markers, like BDNF, are low in people with depression, anxiety, and PTSD.
Research has also shown that exercise makes BDNF go up, but prior to this particular study, it was unclear if exercise had a similar effect on NPY and DOR.
When researchers examined the animals’ brains, they found that the sedentary animals exhibited significantly lower expressions of all three markers compared to the exercisers. Conversely, and unique to this study, the exercisers had healthy levels of all three markers; in other words, the presence of all those acronyms in their brain cells helped fortify them against the debilitating effects of stress.
“I think the takeaway is that exercise provides a potential for the improvement of mental health that may increase resiliency to stress,” said Jay R. Hoffman, Ph.D., FACSM, FNSCA, director of the Institute of Exercise Physiology and Wellness at the University of Central Florida and lead author of the study.
“It’s not a panacea. But if you exercise, you have a better chance [of not developing PTSD]. Can exercise help somebody already suffering from PTSD? We don’t have the data for that. We can ascertain that if you exercise, it reduces your risk.”
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