Category Archives: science

Interleaving versus spaced practice

One thing I’ve been ruminating about lately is if the benefits of interleaving are due to it being a form of spaced practice, or if it does offer its own unique benefits. The benefits of spaced practice are already well-known, and has been recommended by many education experts for decades. According to some experts interleaving is just a form of spaced practice, according to others it isn’t.

However, a key difference between spaced practice and interleaving is that spaced practice usually involves learning the same thing, but spaced apart by a significant length of time. Sometimes the gap between practice sessions is 30 minutes, sometimes several hours. This article got me thinking: Interleaving: are we getting it all wrong?

Interleaving, on the other hand, usually involves learning variations of the same skill, at least according to some practitioners(there’s a lot of debate if interleaving works best only for similar skills rather than totally unrelated material). In my case with the unicycle, or tin whistle, I practice the same exact skill on 2 or more different sized unicycles, sometimes at 10 minute intervals(ABABABA). In other words, is the learning deeper if I learn to juggle or play tin whistle on a 20″ unicycle, or both a 20″ and 24″ unicycle?

My anecdotal experience suggests that yes it does, and in an earlier post on interleaving I did post some evidence supporting this. If you learn the same skill with different equipment, that gives your brain more data points to work with, deepening the learning, and potentially helping you learn faster. I rarely use a true spaced practice approach.

Obviously more research is needed, but until then I’ll continue to use an interleaving approach since I’m obviously doing well using it.

Related article:

Spaced and interleaved practice

Review of “The Age of Genius: The 17th Century and the Birth of the Modern Mind”

Screenshot from 2018-02-15 07-58-17

19th-century painting depicting Galileo Galilei displaying his telescope to Leonardo Donato in 1609



I just finished reading A.C Grayling’s “The Age of Genius: The 17th Century and the Birth of the Modern Mind”.

This book covers a lot of territory in 324 pages. In summary, it’s about how the scientific revolution of the 17th century amidst the tumult of religious war resulted in humans coming to see the world very differently at the end of that century compared to the beginning.

At the beginning of the 17th century, the educated elite of Europe still believed in geo-centrism; by the year 1700, most of the educated elite believed the earth revolved around the sun, among other things.

One of Grayling’s most controversial assertions is that the 30 years war(1618 – 1648) acted as a midwife of the birth of the modern mind. This war was the most destructive in European history until World War I. Millions of people were killed as a result of the 30 Years War, mostly in Germany(which was then called the “Holy Roman Empire”, a loose confederation of German-speaking states primarily divided by religion) where it is estimated that 1 in 3 Germans perished. Many other historians and philosophers disagree with Grayling, believing this war greatly hindered scientific and social progress.

Grayling argues that however devastating this war was, it greatly weakened the Catholic church which had long suppressed free-inquiry, which is essential for science. Wars can also have a direct effect on material science, as rivals figure out how to better engineer weapons(he makes an analogy with the vast improvement of rocketry during World War II by the Germans).

Grayling also argues that the scientific advances of that era were essential for or at least concomitant with social and philosophical advances that led to modern secular democratic states. It just makes sense that if humans are no longer assumed to be at the center of the universe, lots of other erroneous assumptions can also be questioned and pushed aside, including the divine right of kings. This kind of thinking played a huge role in the political revolutions of the 18th and 19th centuries. This paradigm shift also paved the way for Darwin’s theory of evolution in the mid 19th century which put an end to the idea that humans are God’s special creation(as I said before, this book is like a prequel of Dennett’s “Darwin’s Dangerous Idea”).

One little thing that surprised me was the author’s contention that the scientific revolution influenced language, particularly English, French and German. The clarity and precision required for scientific thinking and writing also influenced language in general, according to the author. He even contrasts the long-winded, opaque writing of English authors of the early 17th century with the more clear, economical writings of late 17th century authors to make his point(also remarking that one of the things classicists of the era most admired about ancient Greek and Latin writers was their directness and clarity).

One thing that surprises many people is how practically all the early scientists who launched the scientific revolution were not only very religious but were also alchemists or occult enthusiasts forever searching for the elusive Philosopher’s Stone. Doing real science was more like a side project for some of them. I was already aware of this(in particular when it comes to Newton), but he goes into great detail about how much science had to disentangle itself from alchemy and pseudoscience to become science as we practice it today.

Toward the end of the book, while Grayling celebrates the triumph of scientific rationalism, he warns about attempts at reversing the progress we’ve made since the scientific revolution and Enlightenment. Reason and free speech are under assault, and not just by the religious but by political extremists. I’d also add that the “new age” and various pseudoscience movements are also a threat.

All in all, a good book if you’re into the history of ideas and understanding how the world came to be the way it currently is.

Does practice really make perfect?

2014-05-11 15.49.51Many people I know have trouble learning how to juggle or joggle. I always tell them to practice more, or that “practice makes perfect”. Some of them improve, some of them don’t. After all, I attribute my “success” at joggling to practicing a lot. I do not believe my joggling ability is due to being genetically gifted. On the contrary, as I’ve said many times before on this blog I never excelled at sports and I don’t think I am uniquely well-coordinated. I joggle 5 to 6 times a week, and juggle every day.

Still, as important as practice is, hand-eye coordination is in part genetically determined. The same is true for dance or musical ability. The question is just how big is this genetic component? Or how important is practice? According to this recent study, Deliberate Practice and Performance in Music, Games, Sports, Education, and Professions: A Meta-Analysis:

More than 20 years ago, researchers proposed that individual differences in performance in such domains as music, sports, and games largely reflect individual differences in amount of deliberate practice, which was defined as engagement in structured activities created specifically to improve performance in a domain. This view is a frequent topic of popular-science writing-but is it supported by empirical evidence? To answer this question, we conducted a meta-analysis covering all major domains in which deliberate practice has been investigated. We found that deliberate practice explained 26% of the variance in performance for games, 21% for music, 18% for sports, 4% for education, and less than 1% for professions. We conclude that deliberate practice is important, but not as important as has been argued.

© The Author(s) 2014.

Interesting study. It concludes that while practice is important, it isn’t as important as previously thought. This doesn’t mean you should stop practicing whatever it is you are trying to master, if it often proves challenging for you. It would be ridiculous for someone to give up playing cello just because they’re not as good as Yo-Yo Ma. The same could be said for juggling/joggling. In my opinion, joggling would count as “sport”, and 18% of the variance in joggling performance could be explained by practice, based on the above study.

This is an extremely complex issue, so this study is hardly the final word. I’m sure this study could be interpreted many different ways by people more skilled at reading scientific studies. When it comes to human potential, science at best gives us only a few clues. It is ultimately up to us to find out what we are really capable of.

Why running is better than cycling


Paavo Nurmi at the 1920 Olympics

I could go on and on and on about running, and why it is such a great exercise, if not the best. To further illustrate how great it is, I thought I’d compare it to another endurance cardio exercise, cycling. According to
Participation in road cycling vs running is associated with lower bone mineral density in men:

Cyclists were 7 times more likely to have osteopenia of the spine than runners, controlling for age, body weight, and bone-loading history. There were no group differences in serum markers of bone turnover. Based on the results of this study, current bone loading is an important determinant of whole-body and lumbar spine BMD. Therefore, bone-loading activity should be sustained during adulthood to maintain bone mass.

To be clear, this doesn’t mean that cycling is “bad” for you, it just means that running is better for maintaining bone density, which can help prevent fractures. This is because running is a weight-bearing exercise, and cycling isn’t. All that pounding into the ground stimulates bone mineralization and muscle strength. In experienced runners, their legs have adapted to all this pounding.

If you can’t run due to injuries, jumping rope or T’ai Chi can have similar benefits. If you’re a cyclist, there’s no reason to give it up, just occasionally cross-train with running or other weight-bearing exercises.


How fast were runners a few centuries ago?


It’s an understatement to say that I am obsessed with running. As a I runner, I want to know everything there is to know about running. Being a history buff also makes me curious about the history of running. I’m curious to know how fast runners were centuries ago, and how they trained. It’s fascinating thinking about what they knew, and what they didn’t know, when there was so little science to help guide them.

Centuries ago, runners may have vaguely understood carb-loading, even if they didn’t exactly know what a “carbohydrate” was. It is possible that they knew about interval training and the benefits of hill running. Those runners who ran very long distances must have known about “hitting the wall”, even if they couldn’t explain exactly why it happened, and didn’t have a word or phrase for it. Undoubtedly, runners back then experienced “runner’s high”, though, again, they probably didn’t have a phrase for describing it, nor did they understand why it happened. They obviously didn’t know anything about VO2 Max, lactate thresholds, or fast twitch or slow twitch muscle fibers, beyond maybe a very crude understanding of things associated with them, at best.

Sadly, little survives concerning training methods or running records at various distances before the late 19th century. What little we do have though is revealing. For instance, according to British running performances in the eighteenth century, in 1740, a runner set a record for running 21 miles in 2 hours! That is remarkable! That is a lot faster than me. This is probably one of the fastest speeds recorded for this distance during this time period, which is why it has survived. Most runners back then must have been a lot slower than this.

Besides science being primitive back then, most people in Europe were generally sicklier, and smaller compared to people in the developed world today. Most people lived in poverty. Life expectancy was much shorter, and it was common for people to have suffered from various contagious diseases we now vaccinate for. In 18th century Europe, most people bathed only a few times a year, and hardly anyone brushed their teeth(though they may have picked their teeth or washed their mouths). Very few people had running water, and almost no one had toilets. Indoor air was often extremely polluted due to the use of coal or wood for cooking and heating.

Droughts or a bad growing season often lead to widespread famine, and it wasn’t uncommon for many people to go hungry even during better times. During harsh winters, fresh fruits and vegetables were hard to come by(refrigeration didn’t exist), which could lead to nutritional deficiencies. Even when food was plentiful, it was often contaminated with dangerous pathogens that sometimes killed people. The same was often true of water. Practically all medicine was quackery in that era. One positive back then was that most people were very “athletic”, since the farm work or heavy labor nearly everyone did every day was very physically demanding. Obviously, obesity was almost non-existent, except among the very rich.

The more you think about it, the more amazing it seems that anyone could actually live in conditions like this, never mind how anyone could be healthy enough to run long distances while living in such difficult, unsanitary conditions. In spite of everything, some people ran, and some ran very fast. Try thinking about 18th century runners and all they had to go through next time you run. The demanding work most runners were doing when not running meant they were doing an awful lot of “cross-training”. Sure there were runners in B.C times, but records are even more sketchy from that period.

Still, if I had a time-machine, I would love to go back in time to watch some races, or even participate in some, if they would let me. I wonder what they would think about my joggling! If I could go back in time and talk with these 18th century runners, I’m sure I would learn a lot from them.

Alas, I don’t have a time-machine(yet), but these Age of Enlightenment runners can still inspire us, as well as future generations of runners and other athletes.

Sex differences in athletics

I seldom if ever talk about sex differences in athletic performance on this blog. In large part this is because I know little about them, besides the obvious things, but aside from this, I have long assumed the differences are minimal. Also, since I’m a man, and to the best of my knowledge, have always been a man, I speak from the perspective of a male athlete. Still, I think about 99% of what I post on this blog is relevant to both sexes.

So just recently I stumbled upon this study from January of this year – Female recreational athletes demonstrate different knee biomechanics from male counterparts during jumping rope and turning activities:

Peak knee anterior force was greater in female recreational athletes than in their male counterparts during jumping rope, side-to-forward running, inside turning, and outside turning. Female subjects displayed greater peak knee abduction angles and greater peak knee flexion moments while jumping rope compared to their male counterparts. There were no significant differences between the sexes in knee kinematics and kinetics in the frontal and transverse planes during running and turning motions.
Female recreational athletes exhibited significantly different knee biomechanics compared with male counterparts during jumping rope and turning motions.

This is intriguing. I wonder how much of this has to do with the fact that women generally have wider hips? The above study lead to this –
Gender differences in lower extremity mechanics during running:

Female recreational runners exhibit significantly different lower extremity mechanics in the frontal and transverse planes at the hip and knee during running compared to male recreational runners.
Understanding the differences in running mechanics between male and female runners may lend insight into the etiology of different injury patterns seen between genders. In addition, these results suggest that care should be taken to account for gender when studying groups of male and female recreational runners.

Again differences were found, and they may explain different injury patterns between the sexes. I really have no insights or information to offer here since I have no qualifications in this area. These studies may be garbage for all I know, though I doubt there is some kind of sexist intent. Besides this, I find some parts of these studies difficult to understand, but still, I am fascinated. It makes me wonder though, assuming these differences are for real, how many personal trainers, coaches, and athletes are aware of these differences?

Cinnamon and diabetes


Cinnamon is by far the spice I love the most. Its sweet, strong, complex taste is almost magical to me. In part, this is why I’ve closely followed the news about it for so long, especially about its potential as a type II diabetes treatment(not type I). Early studies on cinnamon suggested it could lower both glucose and cholesterol levels.

A lot more research has been done, and a recent meta-analysis,
Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis.
on cinnamon concluded:

The consumption of cinnamon is associated with a statistically significant decrease in levels of fasting plasma glucose, total cholesterol, LDL-C, and triglyceride levels, and an increase in HDL-C levels; however, no significant effect on hemoglobin A1c was found. The high degree of heterogeneity may limit the ability to apply these results to patient care, because the preferred dose and duration of therapy are unclear.

It looks like there is still some promise here, though if you have type II diabetes or suspect you have it, go see a doctor as soon as possible, don’t try treating it with cinnamon. While this meta-analysis indicates some positive effects, it also notes the inconsistency of some of the evidence. In large part this is because of how the amount of biologically active chemicals in cinnamon are highly variable. Besides this, some of the other hundreds of chemicals in cinnamon may interfere with the glucose-lowering chemicals effects. This isn’t unique to cinnamon though; this is a limitation of just about all other herbs or spices people use for their supposedly therapeutic effects.

To further complicate matters, I believe most scientific studies that have been done on cinnamon used Ceylon cinnamon, often called true cinnamon(cinnamomum verum), rather than cassia, which is also known as cassia cinnamon(Cinnamomum cassia), or colloquially as “Chinese cinnamon”. In North America, cassia or Chinese cinnamon is much more common, and cheaper, than Ceylon(true) cinnamon, and may have somewhat different medicinal properties, besides tasting sweeter than cassia.

In the U.S, what we call “cinnamon” is almost always cassia, and it is what is generally sold in most stores and supermarkets(in Europe, Ceylon cinnamon is much more common). While true cinnamon and cassia are closely related, cassia has a lot more coumarin, which has powerful anticoagulent effects, besides being toxic for the liver. Consuming very large amounts of cassia on a regular basis may be dangerous for some people. This is why Ceylon cinnamon, which has little to no coumarin, is probably safer to use in large quantities.

If you want to purchase true Ceylon cinnamon, you may need to go to a specialty market to find it. Make sure the container clearly says it is “Ceylon cinnamon”. It will almost certainly come from Sri Lanka(Ceylon), which produces about 80 – 90% of the world’s supply.

On a related note, marjoram in the U.S is often labeled as “oregano“. Though they are closely related, oregano is more peppery and zestier than marjoram. Next time you think you’re adding oregano to your pizza or pasta, there’s a good chance it is actually marjoram.

Regardless of its medicinal potential, I love sprinkling cinnamon on oatmeal or pancakes. I love the sweet fire that is cinnamon.



M.C Escher’s “Relativity”. Source: Wikipedia

“The tantalizing discomfort of perplexity is what inspires otherwise ordinary men and women to extraordinary feats of ingenuity and creativity; nothing quite focuses the mind like dissonant details awaiting harmonious resolution”

Brian Greene

Charlatan: America’s Most Dangerous Huckster, the Man Who Pursued him and the Age of Flimflam


John Brinkley

I just finished reading Charlatan: America’s Most Dangerous Huckster, the Man Who Pursued Him, and the Age of Flimflam by Pope Brock, which is a real page-turner. It is one of the better books I’ve read over the past few years. Much of the book reads like a suspense thriller, though it is in essence a biography of the biggest quack in the U.S in the first half of the 20th century, John Brinkley, and his arch-nemesis, Dr Morris Fishbein, editor of the Journal of the American Medical Association and the biggest quack-buster of his time.

Born in North Carolina to a poor family in 1885, John Brinkley would eventually become a merchant of patent medicines, learning all the tricks of the trade of this very popular form of quackery. He obtained a phony degree from a diploma mill to pose as a doctor, and eventually made his way to Milford, Kansas in 1917, a small town in need of a doctor. It was in Milford where he got the idea of surgically transplanting goat testicles into men to restore their virility.

Brinkley had many satisfied patients and his Kansas clinic flourished. He eventually started a radio station(KFKB) to help promote his dubious treatments, almost single-handedly inventing the infomercial in the process. His charisma and marketing genius brought him even more customers and success.

He even started an innovative radio program called “Medical Question Box”, in which he would answer letters on the air from listeners with health problems, and then recommend a specific pharmaceutical treatment(often nothing but colored water). Upon hearing this, many of his listeners who had similar health problems would then purchase the same drug from Brinkley associated pharmacies throughout the Midwest at inflated prices. Brinkley got a cut of each sale, making him a very rich man.

Meanwhile, Morris Fishbein in Chicago would write article after article exposing Brinkley as a quack and calling him a “menace”; this had little affect, and Brinkley would continue to prosper and kill some of his patients.

Brinkley came close to settling in California, sensing that there was a lot more money to be made there than in Kansas. At the time, California’s salubrious, warmer climate attracted a lot of people from around the country seeking rejuvenation and a better life. It also attracted a lot of hucksters seeking to exploit them. Fortunately, Brinkley’s attempt at obtaining a medical license in California was blocked by Fishbein and others who protested to the authorities. Stuck in small-town Kansas, Brinkley continued raking in the dough, and living a luxurious lifestyle which included a growing number of expensive cars.

Fishbein’s indefatigable efforts to get the RTC(forerunner of the FCC) to revoke Brinkley’s radio license finally paid off, and Brinkley was taken off the air. Not long after, Brinkley also lost his medical license in the state of Kansas. What did Brinkley do next? He announced he was running for governor, with only 5 weeks to election day. Though he lost, he came very close to winning; he would occasionally entertain the idea of running for president.

Brinkley was very far from defeated though. He relocated his clinic to Del Rio, Texas and operated a radio station just across the border in Cuidad Acuña, Mexico, out of reach from the U.S government. Free of any regulation, he used this radio station(XER-AM), to promote his quack remedies and political beliefs, first broadcasting in October, 1931. XER would eventually produce the most powerful radio signal in the world, initiating the era of “border blaster” radio. On a clear day, the signal could be picked up as far away as Finland.

Besides promoting his dangerous treatments, increasingly bizarre conspiratorial political beliefs, and complaining about getting persecuted by the establishment, Brinkley also promoted many early country and blues music performers on his radio broadcasts, like the Carter family. Brinkley was by now a very wealthy man with a large mansion full of treasures, a fleet of expensive cars, and spacious yachts he would spend his summers on. Besides this, he was one of the most famous(or infamous) men in the country, and was popular with the locals since his lucrative practice, trailblazing radio station, and his contributions to civic improvements helped Del Rio prosper during the worst years of the Great Depression.

Eventually a competitor came to town, charging a lot less than Brinkley for the same sham procedures. In spite of Brinkley’s popularity and connections, his efforts at driving out this upstart failed, and Brinkley would eventually relocate his clinic yet again, this time to Little Rock, Arkansas.

Brinkley’s hubris in his never-ending war with quack-buster Morris Fishbein would eventually lead to his undoing, but I don’t want to spoil the rest for those who don’t know how it ends.

Brinkley wasn’t just one of the most successful quacks in American history, he was also one of the most prolific serial killers America ever produced. It is difficult to know how many people he killed with his dangerous and dubious treatments. Many more, possibly at least in the hundreds, were maimed.

John Brinkley is a stark reminder of the extreme gullibility of humans when it comes to health matters. Reading between the lines of this book, it’s not just about Brinkley, but is also a powerful indictment of quackery as it exists today. There may be many more laws today to protect consumers, but quackery is very much alive. I see a little bit of Brinkley in some of the better known quacks out there today, who often practice “alternative medicine”, which is what quackery calls itself these days. While they may not be prolific killers like Brinkley, they still prey on the vulnerable, and use the same marketing strategies.

All in all, a very educational, enjoyable, and well-written book for those interested in the history of modern medicine, as well as quackery, or who just like to read a true story that vividly portrays what America was like in the first half of the 20th century.

Is gluten-free the way to be?

A wheat field in Idaho

A wheat field in Idaho

Unless you’ve been living in a cave for the past few years, you’re likely very much aware of the gluten-free diet craze that has swept the country. While it seems like it is “new”, its proponents use the exact same play-book as those who promote fat-free and carb-free diets to the public. The strategy is simple: identify one nutrient or food group as the culprit responsible for the obesity epidemic, and a laundry list of other serious health problems. Remove this food and your health will improve. This time it is gluten, which is simply a protein composite found in wheat and closely related grains, and gives wheat dough its well-known elasticity.

As unscientific as these eliminationist claims may be, there is often a grain of truth to them. While dietary fat may not be the main or only cause of obesity, too much of it isn’t good for you; the same is true of carbohydrate or anything for that matter. And while evidence for gluten being harmful to the general population is lacking, people with celiac disease, who are a tiny minority of the population(about 1%), absolutely have to avoid all gluten containing grains or they will experience severe gastrointestinal problems. There is a slightly larger percentage of the population that is sensitive to or allergic to gluten and wheat, and are better off avoiding it.

Just because some people have serious problems with a certain food doesn’t mean that the general population will benefit from avoiding that food. I’m allergic to bananas, but it would be nonsensical to advocate a banana-free diet to people who aren’t allergic to bananas.

Besides the fact that there are no recognized benefits for the general population, a gluten-free diet can be much more expensive, though it is unlikely to be harmful if a person is still eating a healthful diet otherwise. Ultimately, to help separate the wheat from the chaff, what does the scientific evidence say? According to Gluten-Free Diet: Imprudent Dietary Advice for the General Population? in Journal of the Academy of Nutrition and Dietetics:

There is no evidence to suggest that following a gluten-free diet has any significant benefits in the general population. Indeed, there is some evidence to suggest that a gluten-free diet may adversely affect gut health in those without celiac disease or gluten sensitivity.31 Additional research is needed to clarify the health effects of gluten, and potential consequences of avoiding gluten-containing grains.

So it looks like the general population is unlikely to derive any benefits from a gluten-free diet. If you haven’t been diagnosed with celiac disease or wheat allergy by a medical doctor, you are unlikely to benefit.