Active Grandparents, Sliding Cats and Snapping Hips
And other things I read about recently
The active grandparent hypothesis
Humans are unusual animals in that they live a long time after they stop reproducing. This is a bit weird from an evolutionary perspective, because genes don't really care much about keeping the body healthy and alive after they have been replicated and passed safely to the next generation.
But humans tend to live at least a few decades after their child-bearing years are over. The probable reason is that during this time they can usefully contribute to the well-being of their grandkids and the genes living inside of them. This requires them to be physically active. Studies of the physical activity levels of old hunter-gatherers show that they only drop off a little bit as they age. That’s a big difference from modern environments, where humans tend to spend their later decades with their feet up on the couch or riding around in a golf cart. This is not a natural way to spend the golden years, and there is a heavy price to pay in terms of lifespan and “healthspan.”
Of course, a sedentary lifestyle is unhealthy at any age, but this is especially true after the reproductive years are past. Remember that natural selection doesn't care much about your health after you reproduce, unless you’re’ doing something useful to help your progeny. And the primary signal of usefulness that your body understands is physical activity.
The evolutionary biologist Daniel Lieberman put some of these ideas together in a recent paper describing the “Active Grandparent Hypothesis.” I wasn't able to get full text, but the hypothesis is also discussed in his excellent event book Exercised. And I found an interview were Lieberman talks about some of the main points in the paper. Here are some good quotes from the paper and the interview:
Contrary to the widespread belief that human life-spans until recently were short, hunter-gatherers who survive infancy and childhood tend to live on average seven decades, approximately 20 years past the age at which they cease reproducing.
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Studies by Ralph Paffenbarger shows that as we get older, physical activity actually becomes more, not less, important as we age.
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Physical activity prevents us from spending extra energy on things that may be good for reproductive success but aren’t good for our health. And that’s fat and hormones. When you’re physically inactive, you increase your reproductive output by increasing hormones like estrogen, for example, and progesterone, which increases your risk of cancer. Testosterone as well.
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Physical activity is also important for health because it’s stressful … our bodies mount a whole series of responses to those stresses that are beneficial … The analogy I sometimes like to use is, imagine you spill a cup of coffee on the floor. And then you clean up the floor, but you actually end up cleaning the floor a little bit more than it was before. It’s like an overshoot.
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One of the most important things about physical activity is that it lowers systemic inflammation. It turns out that the major organ that regulates inflammation in your body is muscle.
Early MRI and disability in acute low back pain
A new systematic review finds that early MRI for acute LBP without red flags is associated with increased length of disability. Some key quotes from the paper:
MRI findings of age-related degenerative changes are prevalent in people without LBP.
A recent study found no relationship between MRI changes in the lumbar spine and pain intensity.
[Recent research showed that] lumbar imaging does not improve clinical outcomes in acute LBP cases without suspected serious underlying conditions.
Despite recommendations of clinical practice guidelines against early MRI scanning for acute LBP without red flags, significant proportions of patient with LBP receive early MRI.
Why do animals like sliding?
How should we explain this?
Or this?
Or this?
Why do animals like sliding? An obvious answer is: “because it’s fun.”
But this raises the question: “why is it fun?”
My speculative answer is that all animals have evolved a motivation to engage in efficient locomotion. So they are inherently attracted to activities that get them moving with speed, power and safety, with a minimum of effort. More at the post below:
Comment from Alan Gordon on PRT
A few weeks ago I wrote an article about an interesting new study finding that Pain Reprocessing Therapy (PRT), a psychological treatment for chronic low back pain, worked very well. One of the questions I wanted to answer was:
how did PRT achieve large effect sizes using treatments that appear similar to methods that typically produce small effect sizes? Are there any important differences between the methods?
My article proposed a few possible answers but I found them unsatisfying. Last week Alan Gordon, the therapist who developed PRT and oversaw the study, provided this helpful comment on the article:
Great article, Todd! In my experience, the main difference between PRT and some of the other treatments you listed is the form of exposure. Combining mindfulness, safety reappraisal and positive affect induction maximizes the chance of giving the patient a corrective experience. Once the patient experiences the position or activity with no pain, it often eradicated the illusion that the pain is an accurate reflection of tissue damage. And allows the patient to over the fear of the pain.
He also provided this link to an example of his therapy.
Snapping hip
Ever wonder why your hip joint “snaps” when you slowly lower the foot from a supine leg lift? Apparently it’s the psoas tendon rolling/snapping over the anterior femoral head when the hip is moved from a position of combined hip flexion, abduction and external rotation back to neutral. For more detail and cool videos, check out this Twiter thread from Jimmy Reynolds.
