Humans Adapt Their Gait to Walk in the Laziest Way Possible

Humans are hard-wired to move in ways that require a minimal amount of energy. A new study in Current Biology from Simon Fraser University in Canada finds that while walking, people automatically adjust their gait to be energy efficient, adjusting their step width and frequency to do the least amount of work possible. 

The researchers, from Simon Fraser’s department of biomedical physiology and kinesiology, outfitted volunteers with robotic exoskeletons that forced them to adjust their gait by making them step more or less often than they would naturally as they walked on a treadmill. The participants adapted their step frequency to the optimum energy efficiency after just a few minutes of walking with their new gait, and did so even when the payoff was relatively small (less than 5 percent energy savings).

The robotic exoskeleton used in the study

As study co-author Max Donelan explains in a press release, “the nervous system subconsciously monitors energy use and continuously re-optimizes movement patterns in a constant quest to move as cheaply as possible."

So while you may go on a walk around the neighborhood hoping to get as much exercise as possible, your nervous system is actively making sure you do the least work you can. This makes a lot of sense when you consider that in the world of early humans, using less energy walking around normally might have left you a little extra energy in reserve to run away from a predator or catch up to your dinner. And, as the study points out, being able to constantly adjust your stride for efficiency might help people adapt to new tasks and different terrain, and avoid stride-inhibiting injuries. 

[h/t: Science News]

All images by Greg Ehlers

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Yoga and Meditation May Lead to an Inflated Ego

If you’ve been exasperated for years by that one self-righteous, yoga-obsessed friend, take note: Regular yoga practitioners experience inflated egos after a session of yoga or meditation, according to a forthcoming study in the journal Psychological Science.

Researchers found that yoga and meditation both increase "self-enhancement," or the tendency for people to attach importance to their own actions. In the first phase of the two-part study, researchers in Germany and England measured self-enhancement by recruiting 93 yoga students and having them respond to questionnaires over the course of 15 weeks, Quartz reports. Each assessment was designed to measure three outcomes: superiority, communal narcissism, and self-esteem. In the second phase, the researchers asked 162 meditation students to answer the same questionnaires over four weeks.

Participants showed significantly higher self-enhancement in the hour just after their practices. After yoga or meditation, participants were more likely to say that statements like "I am the most helpful person I know" and "I have a very positive influence on others" describe them.

At its Hindu and Buddhist roots, yoga is focused on quieting the ego and conquering the self. The findings seem to support what some critics of Western-style yoga suspect—that the practice is no longer true to its South Asian heritage.

It might not be all bad, though. Self-enhancement tends to correlate with higher levels of subjective well-being, at least in the short term. People prone to self-enhancement report feeling happier than the average person. However, they’re also more likely to exhibit social behaviors (like bragging or condescending) that are detrimental in the long term.

So if you think your yoga-loving friends are a little holier than thou, you may be right. But it might be because their yoga class isn’t deflating their egos like yogis say it should.

[h/t Quartz]

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Feeling Down? Lifting Weights Can Lift Your Mood, Too
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There’s plenty of research that suggests that exercise can be an effective treatment for depression. In some cases of depression, in fact—particularly less-severe ones—scientists have found that exercise can be as effective as antidepressants, which don’t work for everyone and can come with some annoying side effects. Previous studies have largely concentrated on aerobic exercise, like running, but new research shows that weight lifting can be a useful depression treatment, too.

The study in JAMA Psychiatry, led by sports scientists at the University of Limerick in Ireland, examined the results of 33 previous clinical trials that analyzed a total of 1877 participants. It found that resistance training—lifting weights, using resistance bands, doing push ups, and any other exercises targeted at strengthening muscles rather than increasing heart rate—significantly reduced symptoms of depression.

This held true regardless of how healthy people were overall, how much of the exercises they were assigned to do, or how much stronger they got as a result. While the effect wasn’t as strong in blinded trials—where the assessors don’t know who is in the control group and who isn’t, as is the case in higher-quality studies—it was still notable. According to first author Brett Gordon, these trials showed a medium effect, while others showed a large effect, but both were statistically significant.

The studies in the paper all looked at the effects of these training regimes on people with mild to moderate depression, and the results might not translate to people with severe depression. Unfortunately, many of the studies analyzed didn’t include information on whether or not the patients were taking antidepressants, so the researchers weren’t able to determine what role medications might play in this. However, Gordon tells Mental Floss in an email that “the available evidence supports that [resistance training] may be an effective alternative and/or adjuvant therapy for depressive symptoms that could be prescribed on its own and/or in conjunction with other depression treatments,” like therapy or medication.

There haven’t been a lot of studies yet comparing whether aerobic exercise or resistance training might be better at alleviating depressive symptoms, and future research might tackle that question. Even if one does turn out to be better than the other, though, it seems that just getting to the gym can make a big difference.

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