Our upright gait is not just a defining feature of what it means to be human. It also makes our bodies and brains work better.

Why does walking make us feel good? We all know that a satisfying stroll changes our outlook. Perhaps we realize it all the more today, when so many of us are hunkered down and this simple activity is a challenge. But walking is especially important now, with gyms and team sports shut down. It�??s one of our few accessible forms of exercise but also one that is directly affected by stay-at-home orders. What we usually do automatically now takes serious intention.

Even how we walk has temporarily changed, especially for city-dwellers. It�??s now more social in a peculiar way. We used to obliviously bump shoulders and perhaps mutter apologies while scrolling on smartphones; now we watch each other�??s movements, slightly sashay away and smile at one another�??at a safe distance. Our brains are quickly calculating where the other person is, getting ready for a passing encounter. Walking is somehow more �??mindful�?� now.
What we probably don�??t realize is that walking can be a kind of a behavioral preventive against depression. It benefits us on many levels, physical and psychological. Walking helps to produce protein molecules in muscle and brain that help repair wear and tear. These muscle and brain molecules�??myokines and neurotrophic factors, respectively�??have been intensively studied in recent years for their health effects. We are discovering that they act almost as a kind of fertilizer that assists in the growth of cells and regulation of metabolism. They also reduce certain types of inflammation.

These essential molecules are produced by movement and the increased brain and body activity created by movement. If you�??re not moving about, placing heart and muscle under a bit of positive stress and strain, these molecules aren�??t produced in sufficient quantities to perform their roles. 
Movement through the world changes the dynamics of the brain itself.
Walking is essential to our nature. Walking upright is one thing that sets humans apart; no other animal does it, but we can�??t do without it. At around a year or so of age, we make a unique transition from crawling, from being stable on all fours. We struggle upright, falling a bit, stumbling a bit and eventually walking fluidly and fluently under our own steam.
In our evolutionary history, walking upright set our hands free, allowing us to carry food and tools and children and also to point and gesture. Because we could point to predators and prey in the distance, we could look in the same direction, paying shared attention to what someone is pointing at�??a capacity that demands an elaborate brain system.
Walking is also how we find our way around the world. It is how we created our own internal GPS maps before there was GPS. This gives the lie to how we might think we navigate�??that is, by sight. People who are completely visually-impaired, even from birth, can and do navigate with purpose and direction. They can do this without sight because the experience of bodily movement itself in complicated three-dimensional space is key to creating our cognitive maps.
Those of us with normal sight are fooled by our sense of the three-dimensional world as visual, but to our brains, vision is just one sense contributing to our understanding of space. After all, we can find our way around in a suddenly darkened room. Close your eyes and point to where the door is: That�??s your cognitive map at work. Moving is the thing. It silently updates your position in your GPS without your even realizing it.
Movement through the world changes the dynamics of the brain itself. Recent experiments show that walking increases the strength of the signals in parts of the brain concerned with seeing and other senses, such as touch. This is the biological reality of the phrase �??on the prowl.�?� Walking about helps you discover things more quickly compared to merely sitting in one place.

Experiments by the psychologists Marily Opezzo and Daniel Schwartz of Stanford University have shown that walking boosts creativity. They asked people to quickly come up with alternative uses for common objects, such as a pen. They found that people whom they got to walk before coming up with alternative uses came up with almost twice as many novel ideas as those who remained seated.

We have designed movement out of our world and put more sitting around into it.

Before you start a creatively demanding piece of work, prime yourself by writing down a few questions about what you need to do. Then head off for a 20-minute stroll and bring a voice recorder or a notebook. You�??re likely to find that you generate more ideas than you would have while sitting at your desk. A walking brain is a more active brain, and more activity in the brain can bring colliding ideas and associations at the edge of consciousness to mind�??resulting in the �??a-ha�?� moment of insight.
Granted, going for a walk acts against our in-built tendency to conserve energy. Remember, for most of our history, food was hard to come by. After a long day walking and foraging and hunting, our forebears would sit and maybe tell stories or sing songs. But we�??ve largely solved the food gathering problem now; shops and restaurants and home deliveries make cheap calories easily available. We no longer walk mile after mile to gather food. Instead we can sit and eat, easily. Perhaps too easily. We have designed movement out of our world and put more sitting around into it.
Recent experiments show that as few as three or four days of inactivity reduces muscle mass in the legs, starting to replace muscle with deposits of fat. This isn�??t much of a problem when you�??re 30, but it is when you are 60, needing assistance to stand up from your chair. The cure? Get up, walk about and fight the frailty that can come with aging.

Walking is the movement that we all profit from and have evolved for. Walk we must, and walk we should, to keep our mental and physical worlds open and to stop the walls from closing in.

By  Shane O�??Mara for the Wall Street Journal�??Dr. O�??Mara is professor of experimental brain research at Trinity College, Dublin. This essay is adapted from his new book, �??In Praise of Walking: A New Scientific Exploration,�?� to be published on May 12 by W.W. Norton.

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