Dear Doctors: I just read about these electronic mouthguards that can show if someone has a concussion during contact sports games. Apparently, if you get hit really hard, they will flash and let the coaches know that you need to get out of the game. This seems like a great idea. What took so long?

Dear Reader: You are asking about the news that an international women’s rugby tournament will be introducing the use of an “instrumented” mouthguard that can calibrate the force with which a player is tackled. If that force is powerful enough to cause a head injury, it will trigger a flashing red light within the mouthguard. This, as you say, alerts the coaching staff that the player should exit the game for a medical evaluation.

While contact sports such as rugby and football can be exciting to watch, the repeated tackles and collisions during the game put players at significant risk of head, face and neck injuries. These include concussion, fractures, intracranial bleeds, cerebral contusion, dental and eye injuries, and cervical spine injuries.

Even soccer, in which players use their heads to direct the ball, is coming under new scrutiny. For decades, due in part to cultural attitudes and economic pressures, the issue of head and neck injuries in contact sports flew under the radar.

With the emergence of high-profile cases of chronic traumatic encephalopathy, or CTE, the issue of head injuries in contact sports became a public health concern. CTE is a progressive disease in which repeated blows to the head damage the brain and cause cognitive decline.

Tragically, CTE can be diagnosed only after death, via an autopsy. The awareness of CTE, along with pressure from players, families and the medical community, has led to renewed efforts to protect athletes from playing while injured. That is where the flashing mouthguard enters the picture.

Like a traditional mouthguard, this new so-called “smart” version is made from food-grade thermoplastic that is resilient yet flexible. What makes it different are the tiny motion sensors embedded in the plastic. These sensors use accelerometers to detect the force with which a player is hit head-on and gyroscopes to measure angular and rotational forces.

Because our upper teeth are in a fixed position, they absorb the same impact as the rest of the head. That means the instruments in the mouthguard can provide an accurate picture of what has happened to a player’s head during contact.

The upper limits of an acceptable collision are calibrated using medical studies and biometric and biomechanical data. When one of the smart mouthguards registers contact that exceeds the preestablished limit, it triggers a flashing red light. Due to the difference in the physical size and bone and muscle structures of women and men, the danger zones of the mouthguards are calibrated accordingly.

With this kind of real-time data, players can be pulled from a game even when symptoms are not immediately present. Cumulative hits, another danger of contact sports, can also be tracked. Flashing mouthguards don’t eliminate the risks of contact sports, but they do represent a significant step forward in player safety.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: My husband has prediabetes. I read that going for a walk after you eat can help your blood sugar, so I always do that. But my husband says when you sit down again, your blood sugar goes right back up, so what’s the point? Is that true? I’m not giving up on him joining me.

Dear Reader: Prediabetes is a condition where blood sugar levels are higher than normal, but not yet high enough to meet the threshold for diabetes. However, prediabetes is considered a warning sign of an increased risk of developing Type 2 diabetes.

Type 2 diabetes is when the body can’t use insulin effectively to control blood sugar levels. Sometimes, the body can also no longer produce the required amounts of the hormone. Over time, the chronic high blood sugar of Type 2 diabetes can cause tissue, nerve and organ damage. More serious complications include cardiovascular disease, stroke, kidney issues and blindness. All of this means it’s important to take the prediabetes warning seriously.

Now let’s talk about the post-meal walks that you have added to your routine. Several years ago, a group of researchers in Ireland found that taking a walk after a meal has a beneficial effect on blood sugar. This proved true even when the walk was only five minutes long and taken an hour after eating. Some people in the study had diabetes, and some did not. The beneficial effects on blood sugar occurred in all of the participants, regardless of their diabetes status. Although simply standing after a meal also improved blood sugar numbers, the results were far more modest.

The reason a post-meal walk is good for blood sugar control lies in the muscles. Even the slight contractions, like standing up, help use up glucose available after a meal. When you walk, you are using some of the largest muscles in the body. Those are the gluteus maximus, the hamstrings and the quadriceps. The latissimus dorsi, fan-shaped muscles in the mid-back that help support trunk and arm movement, are also working. When activated, these muscle groups use glucose, which helps prevent the spikes associated with diabetes.

Managing those blood sugar spikes is an important factor in lowering cardiovascular risk. Among people who walked, the post-meal spike was not only less extreme, but the spike was also more gradual. There is also evidence that repeated blood sugar spikes play a role in the development of Type 2 diabetes.

Your husband is correct that blood sugar will rise again after the walk. However, the change will be gradual and less extreme than without the added exercise. Walking smooths out those dangerous spikes and lessens the risk of the health consequences we just discussed. Your husband is fortunate that his blood sugar issues were noticed at the prediabetes stage. With proper diet and exercise, he still has time to prevent an escalation to Type 2.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

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Dear Doctors: We live in Florida, and we keep seeing on the news about people dying from flesh-eating bacteria you can get when you go swimming. It seems like it’s happening a lot more often than it used to. Why is it so hard to be cured when someone gets sick?

Dear Reader: The term “flesh-eating bacteria” refers to certain types of bacteria that can cause a severe, fast-moving infection. These include group A streptococcus, pseudomonas, certain species of clostridium and aeromonas, and vibrio. The cases that you are citing are due to vibrio vulnificus found in warm, coastal waters.

Vibrio vulnificus, often shortened to “vibrio,” is a rod-shaped bacterium with a slight curve shape like a comma. This bacterium thrives in salt and warm water. It’s found in warm marine environments, including the ocean and brackish water. Brackish water is a mix of both salt and fresh water. It’s found in coastal areas such as marshes, lagoons, estuaries, river deltas, and inland lakes and ponds.

The majority of vibrio infections are from eating infected seafood. This is due to undercooked or raw seafood, most commonly oysters and shellfish. Known as vibriosis, symptoms include stomach cramps, nausea, vomiting, watery diarrhea, fever and chills. Vibriosis is unpleasant, but it’s usually not dangerous for healthy individuals. For people with weakened immune systems or underlying conditions such as diabetes or liver disease, the infection can escalate and become severe or even life-threatening. You can destroy vibrio by cooking shellfish to an internal temperature of 145 degrees Fahrenheit for 15 seconds before eating it.

Far less common, and yet far more publicized, are the “flesh-eating” vibrio wound infections you have been hearing about. These infections can occur when the bacteria enter the body through a break in the skin. This can be a cut, scrape, scratch, blister, burn, surgical site, or even a new piercing or tattoo. Initial symptoms of a vibrio wound infection include fever, redness, pain, swelling and discoloration at the entry point. Treatment includes antibiotics and may include removing dead tissue with surgery.

A vibrio wound infection can escalate to a serious condition known as necrotizing fasciitis, which causes tissue death. It progresses rapidly and can lead to organ failure, the need for limb amputation and even death. If vibrio reaches the bloodstream, it can cause a severe, potentially fatal infection called septicemia. Treatment can be difficult due to the rapid progression of the infection. Vibrio is adept at evading and resisting immune response. Prompt treatment gives the best chance of a good outcome.

You are correct that these infections are unfortunately on the rise. This is due to warming coastal waters, which are expanding the habitat of these bacteria. To be safe, never swim in warm salt or brackish water with an open wound, no matter how small. At the first sign of infection, seek immediate diagnosis and treatment.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)