In an effort to reduce concussions, an increasing number of athletes are being equipped with sensors designed to measure impact forces to the head, thus giving coaches and sideline physicians a better sense of injury risk.

At least that's the idea. A Stanford University study suggests that commercially available sensors vary wildly in their assessments, and much depends upon where the sensor is positioned on the head.

Researchers looked at three leading methods: a sensor that adheres to the skin just below the ear, a sensor worn inside a skullcap and sensors embedded in a mouthguard. The research involved test subjects wearing the various sensors while heading a soccer ball traveling at speeds roughly equal to those observed in youth soccer. High-speed cameras recorded the impact, with that data compared with sensor data.

The results showed that the mouthguard produced the most accurate measurement, with the other two sensors faring significantly worse. In fact, the sensors near the ear and in the skullcap over-predicted acceleration of impact by up to 500 percent.

"If these devices over-predicted consistently — say, they were always 50 percent over — then it's probably not a huge issue," said lead study author Lyndia Wu. "But the problem is that they don't correlate with skull motion, which makes it difficult to interpret their measurements and in turn makes it difficult to interpret injury risk predictions."

Body of Knowledge

Electricity travels through copper wire at 96 percent the speed of light. In our bodies, it moves at much slower, varying speeds. The maximum is just 390 feet per second, or less than one-millionth the speed of light (983,571,056 feet per second).

Life in Big Macs

One hour of chopping wood energetically burns 1,156 calories (based on a 150-pound person), or the equivalent of 1.6 Big Macs.

Stories for the Waiting Room

High-school athletes who play on sports teams smoke tobacco products at a lower rate than non-athletes, but they use smokeless tobacco products more, according to a new study by the Centers for Disease Control and Prevention.

Researchers say the lower use of traditional combustible tobacco products may be the result of students recognizing how smoking can hurt athletic performance. Conversely, the higher use of smokeless tobacco products suggests they're perceived as harmless and socially acceptable.

"The fact is," says CDC Director Tom Frieden, "smokeless tobacco products — such as chewing tobacco, snuff or dip — can cause cancer of the mouth, esophagus and pancreas. And the nicotine in these products is harmful to the developing brain."

Mania of the Week

Flagellomania: an abnormal enthusiasm for flogging.

Never Say Diet

The Major League Eating record for chili is 10.5 pounds in eight minutes, held by Bob Kuhns. The amount seems a bit inflated, as eventually was Mr. Kuhns.

Epitaphs

On the tombstone of Owen Moore, buried in a London cemetery:

"Gone away

Owin' more

Than he could pay."

To find out more about Scott LaFee and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.