I just learned a new term: “affective forecast error.” It means failure to accurately predict how much you will enjoy an activity. When I was a young boy, I made some forecast errors about how much I would like soccer and tennis. I told Mom do NOT get me involved in these activities, because I KNOW I will hate them. She made me do them anyway, and four decades of followup data says she was right. As it turns out, these are actually my favorite things to do. Here are some papers I recently looked at that discuss affective forecast errors in relation to exercise. It turns out that (big surprise) people don’t exercise as much if they think it will suck, and their predictions about how much exercise will suck are not always accurate. One potential practical takeaway: exercise (much like dancing or swimming) tends to suck more at the beginning before you are warmed up and feeling the flow. So if you are feeling hesitant to exercise, start slow with something that seems enjoyable, and remind yourself that your attitude might change after you get moving.
Here’s a video of the coolest slide in baseball history:
Was Kurt Cobain right when he sang that it was “OK to eat fish because they don’t have any feelings?” Probably. Even though fish can detect and avoid noxious stimuli, they lack the neural structures that are thought to be required for the production of conscious experiences of pain. But octopuses are smarter than fish. (Side note: yes, octopuses not octopi. The word comes from Greek not Latin.) A recent study argues that they must feel affective pain because their nervous system has the required stuff, they avoid places where they previously experienced injury, gravitate to places associated with relief from pain, and selectively protect injured parts of the body with high levels of discrimination.
Jane Goodall estimated that an adult male chimp is about six times stronger than a comparable human. Chimpanzee strength has been the stuff of legend for many years. Old time carnivals and county fairs often featured wrestling matches between humans and chimps, with the common result being the human getting his butt kicked. In the 1920s, a biologist named John Bauman tried to measure chimp strength at the Bronx zoo by getting them to pull on a rope attached to a dynamometer. A female named Suzette pulled an astonishing 1200 pounds, and this was followed by an 860 pound one-handed pull by a large male named Boma. More recent studies with improved methodology throw some cold water on the chimp super strength story. It seems that chimps are about 1.5 times as strong as a humans pound for pound. What accounts for the difference? Chimps have longer muscle fibers, which makes them more powerful but less efficient, and less precise in their force production. Human ancestors may have been as strong as chimps but about 5 million years ago their muscles adapted to have better endurance and coordination.
Here’s a cool graphic illustrating the complexity of pain. It’s a figure from this paper by Cholewicki and colleagues.
Note that tissue damage (the yellow circles), is just part of the picture. Click here for a web page where you can zoom in on the details.
Losing muscle as you age affects more than just physical function and appearance. Muscle is increasingly being recognized as having the character of an endocrine organ. When muscles contract they release signaling molecules called myokines, which have various regulatory effects throughout the body and brain, affecting visceral fat, inflammation levels, and cognition. For example, here’s a quote from a recent paper on the link between sarcopenia and immune senescence: “Skeletal muscle has emerged as a potent regulator of immune system function [and] might be the central integrator between sarcopenia and immune senescence in an aging biological system. Therapeutic approaches targeting skeletal muscle might be able to restore both muscle and immune system function.”
Here’s a great article (one of many) from Howard Luks, an orthopedic surgeon on whether running can make a meniscus tear worse. Some relevant quotes:
Virtually no one over 40 has a “normal” knee MRI. Upwards of 30-35% of runners over 50 have meniscus tears.
Runners rush into a docs office, they get an MRI, and surgery is scheduled before they give the pain a chance to improve on its own. A meniscus does not have nerves in it. The tear itself doesn’t hurt. The inflammation is because of the tear, and the nearby tissues the torn piece irritates. It may take 6-12 weeks or more for that inflammation from the meniscus tear to settle down
There is very little risk that running will worsen the tear.
Surgery will not prevent arthritis from occurring. On the contrary, osteoarthritis may actually worsen faster if a runner has meniscus surgery.
Have a great week and let me know what you subjects you would like to hear more about.