Why are some baseball players fat? -Quartz

If you follow Major League Baseball this season, you’re watching a game that has become more powerful recently.

After MLB stepped on performance-enhancing drugs in the early 2000s, the league saw a major drop in home runs, but the power hitter seems to be back: players hit far more home runs. home runs than usual this season. . And the rise of the power pitcher continues: pitchers have continued to pitch faster on average since the early 2000s.

Simultaneously, it seems, the players got bigger. Researchers at Penn State University recently analyzed (paywalled) the self-reported heights and weights of baseball players and found that baseball players are, on average, much heavier than they were in the previous century. From 1991 to 2015, 70% of gamers had body mass indices (BMIs) that classified them as overweight or obese. In previous decades, these averages fluctuated between 30% and 40%. “Professional athletes are not immune to the growing obesity crisis and may not provide optimal models of health,” the authors write.

Granted, BMI is often seen as an imperfect measure for assessing whether or not a person is at risk for the negative health consequences that can sometimes come from being bigger, such as heart disease, diabetes, and cancer. “You don’t know the breakdown of muscle versus fat,” said Jayatri Das, a bioscientist who led the development of the Franklin Institute in Philadelphia’s sports area, which features sports science. Many people who are overweight by BMI do not have markers in their blood, such as high cholesterol, associated with carrying extra fat. Athletes in particular can have a deceptively high BMI due to their larger muscles.

“Baseball promotes strength and power training.”

Still, there’s no doubt that baseball players have gotten bigger, especially in recent years. Body mass and BMI increased significantly between 1990 and 2010 – and, according to researchers in a 2014 study (paywall), major league leaders in hitting statistics were particularly likely to be huge.

“Baseball…promotes strength and power training,” Men’s Health pointed out in 2014. As a result, some baseball players may not have the lean muscles characteristic of other athletes.

It seems intuitive: larger bodies should be able to hit a baseball harder. But do physics and physiology agree that increased size leads to better performance?

The goal for hitters – from a physiological standpoint – is to transfer as much of their own energy into moving the ball forward as they hit it with the bat, explains Thomas Karakolis, kinesiologist and author of the article. from 2014. It’s all about kinetic energy, the type of energy used in movement. It is described by the formula k = (1/2)mv2where m is the mass of the system – here, the weight of the batter and bat – and v is the velocity, or speed, which here represents the movement of the batter and bat.

“Theoretically, if a bigger guy is as fast or as strong as another guy, he should be able to hit the ball further.”

To increase the kinetic energy transmitted to the ball, you need to increase the mass and/or velocity without decreasing the other and ensure that no energy is lost when your bat makes contact with the ball. So, “in theory, if a bigger guy is as fast or as strong as another guy, he should be able to hit the ball farther,” Karakolis says.

Bigger muscles probably help. In 2009, Alan Nathan, a retired physicist formerly at the University of Illinois at Urbana-Champaign and lifelong baseball fan, wrote an article (pdf – and, notably, unpublished in a committee-based journal of reading) in which he calculated that If you assume that a baseball player starts out with about 50% of his weight as muscle, every 10% of muscle mass he gains will result in an increase of about 3 .6% to 3.9% of bat speed.

The problem is that if a player gets bigger, even if they also get stronger, they may start to move their bat slower through the zone. This happens because of another aspect of physics: momentum.

Momentum is the tendency of things that are moving to keep moving. It is calculated in two ways: first, it is the product of mass and velocity (p=mv). But “the flip side of momentum is that it also equals force times time,” Das explains.

Hold on to your hats: force equals mass times acceleration, or the rate at which speed increases. Momentum, then, can be defined as: mass x acceleration x time — where in this case, “time” is the amount of time it takes to complete one stroke of the bat.

It’s much easier to move something smaller than something bigger.

It’s much easier to move something smaller than something bigger. Big players have more to move. So they might get less momentum because they get less acceleration in the same amount of time, which means they don’t reach as high a final velocity as smaller players if they spend the same amount of energy. “If you move slower and everything takes longer, it can reduce the amount of force you apply,” Das says.

In other words, even if players increase their mass, they might decrease their speed. And because velocity is squared in the kinetic energy formula, it probably has a bigger effect than mass.

That’s why it’s essential for athletes to not only increase their strength, but also their power, which is a combination of strength and speed, Karakolis says.

The velocity in this practical energy equation – k = (1/2) mv2– comes from our body. “As biomechanists, we call this the ‘kinematic chain,'” he says. “This is how the movement travels from the floor to your body.” When players use their whole body to swing, rotating their hips, torso and shoulders, they get greater total angular velocity, which travels through the bat then, assuming they make contact, the ball.

In physics, there’s something called the “coefficient of restitution”, which Karakolis explains as “the efficiency of energy transferred from one object to another in a collision”. This number, which can be used to calculate how fast objects will move after they collide, is a fraction between zero and one. In baseball, players want their coefficient of restitution to be close to one, which means that all of their body and bat energy is going into the ball. This scenario would be what physicists call a perfectly elastic collision.

To do this, players need to hit the ball at the spot on the bat where they get the most energy transfer – the “sweet spot” – for the longest time, so the ball goes in the right direction. “If you can follow in the same direction as the ball,” says Das. “You maintain the longest contact with the ball and maximize that energy transfer.”

Remember that the ball also arrives very hot at this stage. “As pitchers throw the ball harder, that energy comes in with the ball and can be turned around to go faster,” Karakolis explains. The trick for players, he explained, is being able to stiffen perfectly on impact. “Any lack of rigidity leads to energy losses.” That’s why it’s really important for players to have strong arms and legs and strong cores, so they can stay stable through impact.

There are two other variables in play: the ball and the bat. But as FiveThirtyEight reported earlier this year, we can assume baseballs, at least in MLB, are all the same.

That leaves the stick. The wood used in bats isn’t completely solid, Karakolis says. It wrinkles, ever so slightly, when swung and makes contact with a ball going through the air, which is why there are usually bumps in a well-used bat. Some of the swing’s kinetic energy can also be lost here, so players can resort to something called “bat-boning” to make them even harder. There are fancy ways to do this with vacuum cleaners, but it can also be done by rubbing very hard objects, like animal bones, on the bat. In theory, rubbing harder objects on the bat makes the bat harder by pre-condensing the wood, so the ball doesn’t when hit.

What’s more plausible is that what really causes more horsepower in the sport is simply that hitters get better

There are coatings currently in use that can achieve the same thing. Steve Phillips, former general manager of the New York Mets, told The New York Times that he feels the bats used today are much brighter than before. “When you look at these bats now, they’re so lacquered,” he said. “You don’t even see the grains anymore.”

If – and only if – players can maintain their constant speed while making perfect contact with the ball on a perfectly hard bat, they could hit the ball harder if they’re bigger.

This, of course, is unlikely. What’s more plausible is that what really causes more power in the sport is simply that hitters are getting better: more adept at hitting that sweet spot and following while standing still to transfer as much power. energy as possible.

“That’s why baseball is so fascinating,” Das said. “There are so many variables in play that when you see that home run, it’s like the stars align. It’s a thing of beauty.

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