Some Football Positions Linked to High Blood Pressure

It might not be obvious to those who spend Saturdays cheering on their alma mater on the gridiron, but playing college football is linked to changes that negatively affect the heart.

However, not all players are affected equally — position makes a difference, a new study finds.

In the research, linemen were more likely to develop high blood pressure over the course of a season than players in other positions were, according to the study, published Dec. 5 in the journal JACC: Cardiovascular Imaging.

Linemen tend to be bigger than other players on the field, as their primary job is to block and tackle. Indeed, the linemen in the study had, on average, higher BMIs than players in other positions, such as quarterbacks and wide receivers.

Previous research has shown that former professional linemen have an increased risk of dying from heart disease, but scientists weren't sure what caused this increased risk, the new study said.

This research included 87 freshmen athletes who played on the Harvard University varsity football team between 2008 and 2014. Before each football season began, the researchers measured the athletes' blood pressure and took images of their hearts, according to the study. The same measurements were taken after the season ended.

The researchers looked to see which players had "prehypertension," meaning that their blood pressure fell between what's considered "normal" (120/80 mm Hg) and what's considered hypertension (140/90 mm Hg).

Results showed that before the season began, the rates of prehypertension were similar between linemen and nonlinemen: 57 percent of the linemen had prehypertension, and 51 percent of the nonlinemen had the condition, the researchers wrote.

But at the end of the season, 60 percent of the linemen had prehypertension and another 30 percent had hypertension, while in the nonlinemen, the rates remained the same as in the preseason, the researchers found.

In addition, at the end of the season, cardiac imaging showed changes to the structures of the linemen's hearts that were "concerning in this population of young, otherwise healthy athletes and" that raise "questions about long-term health implications," Dr. Aaron Baggish, the associate director of the Cardiovascular Performance Program at Massachusetts General Hospital and the senior author of the study, said in a statement.

More research is needed on how sports may affect athletes' hearts, Dr. William Zoghbi, the chairman of the cardiology department at Houston Methodist DeBakey Heart and Vascular Center, said an editorial accompanying the new findings. Zoghbi was not involved in the study. 

How Humans Lost Their Tail, Twice

Humans can't seem to keep a tail, suggests new research that finds our early ancestors lost tails not just once, but twice.

The findings, published in the journal Current Biology, not only help explain why people don't wag dog-like tails, but they also shed light on why we all have a tailbone and begin life with an actual tail that gradually disappears.

"Fleshy tails go all the way back to the earliest vertebrate ancestors and are found in very young embryos, so it would be very difficult to get rid of them entirely without causing other problems," author Lauren Sallan told Seeker. "As a result, both fishes and humans have had to stunt growth instead, leaving a buried, vestigial tail much like the legs of whales."

The origins of this mysterious vestigial tail go back to fish. For the study, Sallan, an assistant professor in the University of Pennsylvania's Department of Earth and Environmental Science, analyzed 350-million-year-old hatchlings of the fossil fish Aetheretmon. This jawed fish distant ancestor of terrestrial animals today had both a scaly, fleshy tail and a flexible tail fin, sitting one atop the other.

Sallan found these structures were entirely separate. By comparing the Aetheretmon hatchlings with those of living fish, she found that the two "tails" started out one atop the other and then grew on their own. This discovery overturns at least two centuries of scientific belief that the modern adult fish tail fin was simply added to the end of an ancestral tail shared with land animals.

The disconnect means that the two tails went on their own evolutionary paths. Fish lost the fleshy tail and kept the flexible one to improve their swimming. Having just the back fin, she explained, "allows for more refined movements, which a muscular tail (originally present for power swimming) would disrupt."

Fish that evolved to become semi-aquatic and then land-dwelling animals lost the flexible back fin, but kept the fleshier one that over time became the familiar appendage we now see on dogs, cats, cows and many other animals. As dogs show, tails are useful for visual communication, slapping away flying insects and other functions.

RELATED: Dogs Remember Even the Stupid Things We Do

Adult apes, including human ancestors, took the tail loss process a step further, Sallan said, "losing the remaining bony tail for better upright movement. Like fish, the remnants of an embryonic bony tail are buried in our lower backs—the coccyx or tailbone—stunted by a loss of molecular signals that would otherwise cause it to grow out like an arm or leg. Thus, humans and fish embryos share mechanisms for controlling tail form."

The fossil record for early apes is not great, but since apes lack tails, she thinks our primate ancestors lost them when they first started to walk on two legs. Monkeys that often walk this way have stunted tails, further proving that tails can get in the way of moving around while upright.

Pearl Harbor Subs: See Underwater Graves in Live-Stream Dives

During the predawn hours of Dec. 7, 1941, Japanese crewmembers boarded two mini submarines to take part in the surprise attack on Pearl Harbor. Now, 75 years later, the public can see an underwater live stream of these two historic submarines resting at the bottom of the Pacific, according to the National Oceanic and Atmospheric Administration (NOAA).

Maritime archaeologists and scientists will direct a remotely operated vehicle (ROV) from NOAA's ship Okeanos Explorer, a federally funded U.S. ship that uses real-time broadband satellite communications to send data to a live audience onshore, according to NOAA.

The live stream will take place here at 6:30 a.m. local time in Hawaii (11:30 a.m. EST) on Wednesday, Dec. 7. [Lost in Pearl Harbor: Photos of Sunken WWII-Era Navy Plane]

The two submarines may be corroded and covered with barnacles now, but 75 years ago they were in working condition. However, their operations were short-lived. One of the mini subs fired on the USS Ward, which then fired back, sinking it 90 minutes before the Japanese bombed Pearl Harbor by air, NOAA reported.

These shots marked the first time American forces fired on the enemy during World War II, NOAA reported. However, American personnel didn't immediately warn their counterparts on base of the intrusion, NOAA said.

The USS Ward survived the attack, but it didn't survive the war. Exactly three years after the Pearl Harbor attack, a kamikaze attack sank the ship in the Philippines on Dec. 7, 1944, according to NOAA.

The ROV live stream will also explore a second mini submarine — one that disappeared the morning of the attack. It was found in shallow waters in 1951, and later the U.S. Navy raised it and dumped it in deeper waters farther out to sea.

The University of Hawaii's Undersea Research Laboratory rediscovered it in 1992 and has periodically visited it with submersibles, the last time in 2013, NOAA said.

This Pearl Harbor anniversary will see another historic event: Japanese Prime Minister Shinzō Abe will visit the harbor with President Barack Obama in late December, making Abe the first Japanese leader to visit the site since the attack, according to Reuters.