For some, it's a serious sport. For others, just a way to let loose. But despite its casual association with fun and sun, surfing has a richer and deeper history than many realize.

For the people of Hawaii, wave sliding was not just a recreational activity, but one with spiritual and social significance.  Like much of Hawaiian society, nearly every aspect of surfing was governed by a code of rules and taboos known as kapu. Hawaiians made offerings when selecting a tree to carve, prayed for waves with the help of a kahuna, or an expert priest, and gave thanks after surviving a perilous wipeout. Certain surf breaks were strickly reserved for the elite. 

But it wasn't just a solemn affair. Surfers competed and wagered on who could ride the farthest, the fastest, or catch the biggest wave with superior skill, granting respect, social status, and romantic success. Though it was later called the sport of kings, Hawaiian men and women of all ages and social classes participated, riding surfboards shaped from koa, breadfruit, or wiliwili trees.

Today, surfing is a multi-billion dollar global industry, with tens of millions of enthusiasts worldwide. And though relatively few of these surfers are aware of the once-crucial wave chants or board carving rituals, Hawaiians continue to preserve these traditions nearly washed away by history's waves.

From the TED-Ed Lesson The complicated history of surfing - Scott Laderman

Animation by Silvia Prietov

In some cases, a concussion can be hard to diagnose because the symptoms unfold slowly over time. That's often true of subconcussive impacts which result from lower impact jolts to the head than those that cause concussions. This category of injury doesn't cause noticeable symptoms right away, but can lead to severe degenerative brain diseases over time if it happens repeatedly. 

Take soccer players, who are known for repeatedly heading soccer balls. Using a technique called Diffusion Tensor Imaging, we're beginning to find out what effect that has on the brain. In 2013, researchers using this technique discovered that athletes who had headed the ball most, about 1,800 times a year, had damaged the structural integrity of their axon bundles. The damage was similar to how a rope will fail when the individual fibers start to fray. 

Those players also performed worse on short-term memory tests, so even though no one suffered full-blown concussions these subconcussive hits added up to measurable damage over time In fact, researchers know that an overload of subconcussive hits is linked to a degenerative brain disease known as Chronic Traumatic Encephalopathy, or CTE. People with CTE suffer from changes in their mood and behavior that begin appearing in their 30s or 40s followed by problems with thinking and memory that can, in some cases, even result in dementia.

From the TED-Ed Lesson What happens when you have a concussion? - Clifford Robbins

Animation by Boniato Studio

How Concussions Affect the Brain

Each year in the United States, players of sports and recreational activities receive between 2.5 and 4 million concussions. How dangerous are all those concussions? The answer is complicated, and lies in how the brain responds when something strikes it.

The brain is made of soft fatty tissue, with a consistency something like jello. Inside its protective membranes and the skull's hard casing, this delicate organ is usually well-shielded. But a sudden jolt can make the brain shift and bump against the skull's hard interior, and unlike jello, the brain's tissue isn't uniform. It's made of a vast network of 90 billion neurons, which relay signals through their long axons to communicate throughout the brain and control our bodies. This spindly structure makes them very fragile so that when impacted, neurons will stretch and even tear. That not only disrupts their ability to communicate but as destroyed axons begin to degenerate, they also release toxins causing the death of other neurons, too. his combination of events causes a concussion.

The damage can manifest in many different ways including blackout, headache, blurry vision, balance problems, altered mood and behavior, problems with memory, thinking, and sleeping, and the onset of anxiety and depression. Every brain is different, which explains why people's experiences of concussions vary so widely. Luckily, the majority of concussions fully heal and symptoms disappear within a matter of days or weeks. Lots of rest and a gradual return to activity allows the brain to heal itself. On the subject of rest, many people have heard that you're not supposed to sleep shortly after receiving a concussion because you might slip into a coma. That's a myth. So long as doctors aren't concerned there may also be a more severe brain injury, like a brain bleed, there's no documented problem with going to sleep after a concussion.

The data show that at least among football players, between 50 and 80% of concussions go unreported and untreated. Sometimes that's because it's hard to tell a concussion has occurred in the first place. But it's also often due to pressure or a desire to keep going despite the fact that something's wrong. This doesn't just undermine recovery. It's also dangerous. 

Our brains aren't invincible. They still need us to shield them from harm and help them undo damage once it's been done.

From the TED-Ed Lesson What happens when you have a concussion? - Clifford Robbins

Animation by Boniato Studio

Fun Fact Friday!

Caffeine can ramp up the body's ability to burn fat. In fact, some sports organizations think that caffeine gives athletes an unfair advantage and have placed limits on its consumption. From 1972 until 2004, Olympic athletes had to stay below a certain blood-caffeine concentration in order to compete.

From the TED-Ed Lesson How does caffeine keep us awake? - Hanan Qasim

Animation by Adriatic Animation

How to Practice Effectively

Mastering any physical skill, be it performing a pirouette, playing an instrument, or throwing a baseball, takes practice. Practice is the repetition of an action with the goal of improvement, and it helps us perform with more ease, speed, and confidence. 

There are many theories that attempt to quantify the number of hours, days, and even years of practice that it takes to master a skill. While we don't yet have a magic number, we do know that mastery isn't simply about the amount of hours of practice. It's also the quality and effectiveness of that practice. Effective practice is consistent, intensely focused, and targets content or weaknesses that lie at the edge of one's current abilities. So if effective practice is the key, how can we get the most out of our practice time? 

Below are 4 tips for practicing better for just about anything!

1. Focus on the task at hand. Minimize potential distractions by turning off the computer or TV and putting your cell phone on airplane mode. In one study, researchers observed 260 students studying. On average, those students were able to stay on task for only six minutes at a time. Laptops, smartphones, and particularly Facebook were the root of most distractions. 

2. Start out slowly or in slow-motion. Coordination is built with repetitions, whether correct or incorrect. If you gradually increase the speed of the quality repetitons, you have a better chance of doing them correctly. 

3. Next, frequent repetitions with allotted breaks are common practice habits of elite performers. Studies have shown that many top athletes, musicians, and dancers spend 50-60 hours per week on activities related to their craft. Many divide their time used for effective practice into multiple daily practice sessions of limited duration. 

4. Finally, practice in your brain in vivid detail. It's a bit surprising, but a number of studies suggest that once a physical motion has been established, it can be reinforced just by imagining it. In one study, 144 basketball players were divided into two groups. Group A physically practiced one-handed free throws while Group B only mentally practiced them. When they were tested at the end of the two week experiment, the intermediate and experienced players in both groups had improved by nearly the same amount. 

As scientists get closer to unraveling the secrets of our brains, our understanding of effective practice will only improve. In the meantime, effective practice is the best way we have of pushing our individual limits, achieving new heights, and maximizing our potential.

From the TED-Ed Lesson How to practice effectively…for just about anything - Annie Bosler and Don Greene

Animation by Martina Meštrović

Football Physics: The Science Behind the Banana Kick

In 1997 in a game between France and Brazil, a young Brazilian player named Roberto Carlos set up for a 35 meter free kick. With no direct line to the goal, Carlos decided to attempt the seemingly impossible. His kick sent the ball flying wide of the players, but just before going out of bounds it hooked to the left and soared into the goal.

According to Newton’s first law of motion, an object will move in the same direction and velocity until a force is applied on it. When Carlos kicked the ball he gave it direction and velocity, but what force made the ball swerve and score one of the most magnificent goals in the history of the sport?

The trick was in the spin. Carlos placed his kick at the lower right corner of the ball, sending it high and to the right, but also rotating around its axis. 

The ball started its flight in an apparently direct route, with air flowing on both sides and slowing it down. On one side, the air moved in the opposite direction to the ball’s spin, causing increased pressure, while on the other side—the air moved in the same direction as the spin, creating an area of lower pressure. 

That difference made the ball curve towards the lower pressure zone. This phenomenon is called the Magnus effect.

This type of kick, often referred to as a banana kick, is attempted regularly, and it is one of the elements that makes "The beautiful game" beautiful. 

But curving the ball with the precision needed to both bend around the wall, and back into the goal is difficult. Too high and it soars over the goal. Too low and it hits the ground before curving. Too wide and it never reaches the goal. 

Not wide enough and the defenders intercept it. Too slow and it hooks too early or not at all. Too fast and it hooks too late.

The same physics make it possible to score another apparently impossible goal—an unassisted corner kick.

The Magnus effect was first documented by Sir Isaac Newton after he noticed it while playing a game of Tennis back in 1670. It also applies to golf balls, Frisbees and baseballs. In every case the same thing happens: the ball’s spin creates a pressure differential in the surrounding airflow that curves it in the direction of the spin.  

And here’s a question: could you theoretically kick a ball hard enough to make it boomerang all the way around back to you?  Sadly, no. Even if the ball didn’t disintegrate on impact or hit any obstacles, as the air slowed it, the angle of its deflection would increase, causing it to spiral into smaller and smaller circles until finally stopping. And just to get that spiral you’d have to make the ball spin over 15 times faster than Carlos's immortal kick. So good luck with that.

From the TED-Ed Lesson Football physics: The “impossible” free kick - Erez Garty

Animation by TOGETHER

Just jammin’ with our Olympic vibes. Are you watching the games?

From the TED-Ed Lesson Football physics: The "impossible" free kick - Erez Garty

Animation by TOGETHER

The Olympics begin today! 

“The most important thing in the Olympic Games is not to win but to take part, just as the most important thing in life is not the triumph but the struggle. The essential thing is not to have conquered but to have fought well.” -The Olympic Creed

From the TED-Ed Lesson How playing sports benefits your body ... and your brain - Leah Lagos and Jaspal Ricky Singh

Animation by Kozmonot Animation Studio

Today marks the 120th anniversary of the first modern Olympic Games, which were staged in Athens in 1896. Thousands of years in the making, the Olympics began as part of a religious festival honoring the Greek god Zeus in the rural Greek town of Olympia.

For more on the origin of the Olympics, check out the TED-Ed Lesson The ancient origins of the Olympics - Armand D'Angour

Animation by Diogo Viegas

When Dick Fosbury couldn't compete against the skilled high jumpers at his college, he tried jumping in a different way -- backwards. Fosbury improved his record by nearly half a foot and continued to amaze the world with his new technique all the way to Olympic gold. Nowadays, all competing high jumpers use the technique that became known as the ‘Fosbury Flop’. But what’s the secret behind this technique?

It lies in a physics concept called the ‘Center of Mass’. With the old, pre-Fosbury techniques, the jumper had to apply enough force to lift his center of mass above the bar by a few inches in order to clear it. The genius of the Fosbury Flop is that the jumper can apply the same amount of force, but raise his body much higher than before. So even when his center of mass can’t go any higher, his arcing body can.

From the TED-Ed Lesson An athlete uses physics to shatter world records - Asaf Bar-Yosef

Animation by NEIGHBOR

♫♫ I believe I can flyyyyyy ♫♫

From the TED-Ed Lesson The math behind Michael Jordan’s legendary hang time - Andy Peterson and Zack Patterson

Animation by Oxbow Creative