Newsletter #272

Everyone knows, at least on a theoretical level, that exercise is good for you. Yet the majority of Americans do not meet established physical activity guidelines — and the proportion of people who do engage in enough activity decreases with age.

There are all kinds of reasons why this might be the case. One factor, which I have observed, is that some people just aren’t into conventional gym-based regimens. That’s why I was encouraged to come across two new studies which examined the effects of Polish folk dancing and martial arts training on various parameters of cardiometabolic health, as well as cognition, in older adults.

Aside from being more engaging, these types of activities may also confer unique benefits, especially for the brain. We have gleaned from animal research that exercising in an “enriched” environment, where they have to deal with unpredictable situations and solve problems, results in greater improvements in cognitive function, compared to either exercise or cognitively demanding stimuli alone. This was eventually replicated in humans through a cleverly designed trial, in which researchers had participants engage in conventional aerobic exercise, memory training, or a “designed sport” intervention that combined both physical and cognitive demands. After eight weeks, those in the designed sport group showed the greatest cognitive gains, as well as improvements in cardiovascular measures.

Polish researchers recruited 41 healthy older adults (around 70 years old) and randomized them to three groups: dance training, balance training, and control. The dance and balance groups trained three times per week for 12 weeks, with each session lasting 50 minutes.

After 12 weeks, the dance group saw a significant improvement in insulin sensitivity, measured via HOMA-IR, going from 3.1 ± 2.3 to 2.0 ± 1.2. To put this into perspective, HOMA-IR above ~1.8 indicates early insulin resistance and above 2.9 is significant insulin resistance, meaning that your body needs to churn out more insulin to rein in the same amount of blood sugar. So these folks went from pretty serious insulin resistance down to a milder level, approaching normal insulin sensitivity.

The training also resulted in shifts in levels of exerkines, or factors that are secreted in response to physical exercise. Most notably, concentrations of irisin rose after 12 weeks of training (from 15.6 ± 4.3 to 17.6 ± 4.5 ng/ml in the dance group). Irisin is thought to cross the blood-brain barrier and stimulate expression of BDNF in the central nervous system, and thus it is considered a crucial mediator of the beneficial effects of exercise on brainpower. Furthermore, irisin plays a role in regulating blood sugar, and indeed improvements in insulin sensitivity in these participants were associated with levels of circulating irisin.

Finally, both training programs (but not controls) led to decreases in blood pressure. The dance group saw average reductions in systolic and diastolic blood pressure of –13 mmHg and –6 mmHg respectively, with similar improvements in the balance group (isometric exercise is surprisingly effective at lowering blood pressure). This is a level of reduction comparable to what is achieved by some anti-hypertensive medications, and corresponds to a 40% lower risk of death by heart attack, and a 30% reduced risk of coronary artery disease.

Researchers in Gdańsk recruited 40 older adults and split them into two groups: judo and control. Subjects in the judo group participated in judo training sessions three times per week for three months, with each training session lasting 45 minutes.

After 12 weeks, the judo group showed a significant improvement in cognitive performance, which was measured through the Stroop test. The Stroop test assesses executive function, by testing a person's ability to suppress habitual responses. Notably, response inhibition in the Stroop test has been shown to be related to driving performance, so these measures of cognitive control can translate to real life more than you might suspect. And it makes sense that judo would be particularly advantageous for boosting this ability. A prior study that compared martial arts training to aerobic activity found that only martial arts resulted in improved executive function. This was attributed to the increased cortical recruitment needed to meet the complex motor demands of martial arts, compared to the more repetitive actions of walking, which in turn led to greater blood flow to areas of the brain involved with executive function.

Participants also experienced an increase in peripheral brain-derived neurotrophic factor (BDNF) levels in response to the judo training, while controls saw a slight decrease. BDNF is a growth factor that is involved in learning and memory (sometimes referred to as "fertilizer for your brain"). Previous research has found that open skill activity (like playing a sport) can elicit a bigger boost in serum BDNF, compared to a closed skill activity of equal intensity (like running). This boost in growth factors could have contributed to the observed improvement in executive function.

Finally, practicing judo resulted in increased muscular strength and balance in these subjects. This is especially key for older adults, who are more vulnerable to falling and who really need the stimulus of intense exercise to experience beneficial adaptations and to maintain muscle mass as they age.

🤖 Fear of new technology goes back literally thousands of years.

One of my favorite Twitter (or is it X?) accounts is the Pessimists Archive, which documents examples of people expressing moral panic regarding emerging technologies that have since become commonplace and widely accepted, like airplanes, television, headphones, even bicycles. Most of these gloomy takes, needless to say, have not aged well.

These examples usually come from newspaper clippings from the past century or so. However, this brand of apprehension actually goes back much further than that. Indeed, Socrates was wary of the impact of books on education and society. Yes, books.

If you know a little bit about Socrates and his process, this kind of makes sense. He felt that face-to-face communication was the only effective way to convey and develop knowledge. Books, on the other hand, are necessarily one-sided, lacking a back-and-forth dialogue between reader and author. (Socrates actually might have enjoyed Twitter and other social media platforms, now that I think about it)

In the Phaedrus, Socrates says this, of the god who purportedly gave humans the gift of writing:

“And in this instance, you who are the father of letters, from a paternal love of your own children have been led to attribute to them a quality which they cannot have; for this discovery of yours will create forgetfulness in the learners' souls, because they will not use their memories; they will trust to the external written characters and not remember of themselves. The specific which you have discovered is an aid not to memory, but to reminiscence, and you give your disciples not truth, but only the semblance of truth; they will be hearers of many things and will have learned nothing; they will appear to be omniscient and will generally know nothing; they will be tiresome company, having the show of wisdom without the reality.”

(And yes, this is pretty ironic, because the only reason that we know about Socrates’ concerns about writing in the first place is because Plato wrote them down for posterity, and those words were subsequently reproduced in books)

LMNT Electrolyte Powder Packets

Given that it has been extremely hot in the US this past week, we’ve been paying a lot more attention to our electrolyte intake recently, especially while exercising and playing sports.

To that end, we recommend this product because it's significantly higher in sodium than most sports drinks that you see at grocery stores, and sodium is the electrolyte that you need to be most acutely concerned about when you're sweating a ton.

It's also a very "clean" product, free of additives that could bother some individuals, and it comes in an array of interesting flavors that help balance out the saltiness of the supplement.

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Physical Activity and Mortality — from How Much Physical Activity Do We Need?

The benefits of moving more and sitting less aren’t really up for serious debate, and research suggests that most of us are failing to get enough.

But this raises some key questions: how much physical activity do we actually need? What is the proper dose for maximizing your lifespan and healthspan? And does too much exercise lead to diminishing returns — or even overt harm?

In this lesson, we break down what the research says, based upon data pooled from hundreds of thousands of people who were followed for more than a decade.

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