Filed under: Environment
It’s important to get enough water, especially when it’s hot. However, too much water can lead to a dangerous condition known as hyponatremia in which the sodium levels in your blood drop too low. It’s often caused by drinking too much water and is common among military personnel, athletes, and hikers. Significant weight gain (due to fluid retention) during exercise can occur, along with longer finish times for endurance activities. If you have a Body Mass Index (BMI) below 20, you are more likely to develop this condition. For more in-depth information, read HPRC’s InfoReveal on over-hydration.
Sweat is a critical function when you’re performing in hot environments. As your body absorbs heat from the environment, your nervous system activates sweat glands to release sweat. The moisture on your skin then evaporates, taking heat away from your body and cooling you off.
Protective clothing impedes the evaporation of sweat and the heat exchange between you and the environment, a condition known as “evaporative resistance.” This means that the exposed parts of your body will cool off more quickly than the parts that are covered, but they are also more prone to insect bites. Reports from Marines and National Park employees feeling “excessive heat” and a loss of sweating sensations after applying moderate to high amounts of DEET to their skin brought the safety of this insect repellent into question.
In a recent study, researchers found that when 33% DEET lotion is applied according to military protocol, it does not interfere with sweat production or other physiological responses. Nor does it interfere with the evaporation process necessary for cooling to take place. Researchers concluded that 33% DEET can be worn safely during military and occupational activities performed in hot, insect-infested environments. Similar studies have found oil- or alcohol-based repellents may increase core temperature by reducing sweat evaporation rate but do not affect sweat production. The military-approved form of DEET is polymer-based.
You can watch a YouTube video about the science behind the study.
DEET is considered by the EPA to be a toxic pesticide. It should be used with caution and as directed. More information about DEET, its uses, and warnings can be found on the EPA fact sheet. As of 2004, DEET was considered safe for use on children older than two months of age. Specific information on its use and effect on children can be found in the EPA TEACH chemical summary.
Increasing the strength of your respiratory muscles (the ones that help you breathe: your diaphragm and the muscles between your ribs) will improve aerobic fitness, especially for long-duration tasks. Respiratory muscle training (RMT) can be achieved through whole-body aerobic exercise, upper-body strength conditioning, and some commercial RMT devices. However, using your military Pro Mask or other commercial mask device as a method of RMT is not going to prepare you for higher elevations. Studies have also found that RMT only slightly improves performance in those who are already aerobically fit, (i.e., military personnel); it has somewhat more benefit for those less fit or with chronic conditions. Your Pro Mask was made to protect your lungs, eyes, and face from chemical and biological agents, radioactive particles, and battlefield contaminants. It does not create enough airflow resistance to help improve aerobic capacity, and it wasn’t designed to be exercise equipment. In addition, there is no scientific evidence to show that using commercial masks at normal altitudes will improve your performance at high altitudes. You can read more from USARIEM about using Pro Masks and commercial products for exercise training, as well an overview of current information and recommendations.
Being able to hear well is crucial for a Warfighter, not only for effective communication but also for survival. Noise-related hearing loss, including tinnitus, can be a tactical risk for individual and unit effectiveness. Blast injuries from improvised explosive devices (IEDs), RPGs, and mortar rounds are the largest cause of hearing loss for forces in Iraq. Unfortunately, it has become an "invisible" injury and an accepted outcome of military service. Compensation payments for hearing loss as the primary disability increased 319% between 2001 and 2006. While the military has done extensive research and established standards regarding noise and noise exposure, here are a few things you can do to help minimize the effects of this occupational hazard.
- Wear hearing protectors when firing weapons or traveling in noisy vehicles or aircraft.
- Make sure that earplugs such as combat arms earplugs (CAE) fit properly to protect your hearing and still communicate effectively.
- Replace lost or damaged hearing protectors as soon as possible.
- Limit exposure to “annoying noise” during normal daily activities. Trying to ignore noise can increase heart rate and blood pressure, cause sleep difficulties, and lead other negative health consequences.
- Report any signs of hearing loss as soon as possible.
While there is currently no cure for tinnitus, there are treatments available. Noise pollution may be an inevitable part of serving in the military, but it doesn’t have to leave you with a permanent reminder. Do what you can to help hold on to your hearing.
The DoD Hearing Center of Excellence is committed to preventing, treating, and rehabilitating hearing loss and auditory injury for service members and veterans. The HCE offers evidence-based clinical care in collaboration with other organizations and Centers of Excellence to improve quality of life and raise awareness about noise pollution and occupational safety.
Pentagon scientists are hoping to build special gear designed to turn divers into veritable Aquamen (and Aquawomen). Although it’s still in the research phase, the new system would protect divers from the adverse effects of diving too deep or surfacing too fast. Sensors would read and adjust to a diver’s physical signs as well as help control levels of nitric oxide to prevent the decompression sickness known as “the bends.” When a diver ascends too quickly, bubbles form inside the body, which can block the blood vessels in the spinal cord and disrupt the nervous system. It can be very painful and can lead to joint pain, paralysis, and even sudden death if a diver is not careful.
The new diving gear will be a portable and versatile system that can potentially serve for use in other special operations as well as for civilian divers. This system will have to be designed for the most extreme combat dive profiles, which sometimes require a 35,000-meter free-fall from an aircraft, diving 200 feet below the surface for at least two hours, surfacing, and immediately diving again, followed by continued protection after being picked up in an unpressurized aircraft. This is one of DARPA’s most recent Small Business Innovation research proposals for 2013.
Most people associate dehydration with hot weather. Here’s news: You can experience dehydration in cold weather too. Being active outside in cold weather for less than two hours doesn’t usually present a problem. But for long-term exposure such as a field deployment, which can last anywhere from a few days to several weeks, the combination of heavy clothing and high-intensity exercise can lead to increased sweating and the possibility of dehydration. You may not feel as thirsty in cold weather as in other climates, because your body chemistry impairs your brain’s ability to tell you when to hydrate. Cold weather also has the effect of moving body fluids from your extremities to your core, causing increased urine output and adding to dehydration.
The bottom line: When in cold climates, don’t rely on thirst to be an indicator of hydration. Drink often, before you’re thirsty. Water and sports drinks are the best fluids to maintain hydration, even in cold weather conditions. When you’re in a situation where you need to monitor your hydration level keep in mind that carbonated and caffeinated beverages (including energy drinks) have a dehydrating effect since they increase urine flow. Also avoid alcohol consumption in cold weather. It gives a temporary feeling of warmth but interferes with the body’s ability to retain heat since shivering, the normal response to maintain body temperature, is delayed.
Sometimes it’s not easy to hydrate as much as you need, especially when on a mission. One way to measure your hydration status is to monitor the color and volume of your urine. (Snow makes a good test spot.) Dark, scanty urine is an indication of dehydration. Ideally, urine should be light yellow to clear. Enjoy getting some exercise in the cold weather, but be sure to keep your water bottle in tow.
Fort Drum recently opened a “Mountain Functional Fitness Facility.” In keeping with the goal of overall combat fitness, the facility’s purpose is to help soldiers become strong and agile for combat while deployed in both cold conditions and rough terrain such as rugged mountainous environments.
“Functional fitness” focuses on developing specific muscle movements and overall athleticism rather than building up specific muscles. This new center features state-of-the-art equipment and the mission of helping soldiers become conditioned to operate in realistic situations where both strength and agility training are mission critical. Check out this report in Business Insider for additional photos.
As winter approaches here in the northern hemisphere, staying active requires more planning to be safe and comfortable. Here are some tips for exercising in cold weather conditions:
- Since medical conditions such as Raynaud’s, cardiovascular disease, and asthma can be exacerbated by climate changes, be sure to check with your doctor before exercising in the cold.
- Check out these tips from the Mayo Clinic, which include dressing in layers that include a synthetic material such as polyester or polypropylene close to the skin (avoid cotton, since it soaks up the sweat!) and paying close attention to your extremities, especially your fingers and toes, since the circulation to these areas decreases in cold weather.
- The American College of Sports Medicine also has a Position Stand on preventing cold-weather injuries during exercise that emphasizes being able to recognize the signs and symptoms of hypothermia and frostbite, as well as monitoring wind-chill temperature. The signs and symptoms of hypothermia can vary, but in general watch for feeling cold, shivering, apathy, and social withdrawal. Also watch for the early stages of frostbite (which precede the deep frostbite that can cause major tissue damage) in which you’ll feel burning, numbness, tingling, itching, or cold sensations.
If you pay attention to these guidelines, you can continue to stay fit all winter long.
Before the end of October of 2012, the Army will issue to all soldiers fire-resistant ACUs that have been factory treated with an EPA-approved insect repellent called permethrin. This method may be a cleaner and safer way of repelling insects compared to DEET, another long-lasting insect repellent. The Army has been using permethrin for nearly 20 years in the form of liquid or spray, and by treating ACUs, soldiers will experience better, longer-lasting protection against ticks, fleas, mosquitos, and other insects that carry diseases such as malaria, West Nile virus, and Lyme. Other advantages include not having to worry about remembering to apply insect repellant and whether you’re applying it correctly. Uniforms treated with permethrin have been used by the Marine Corps since 2007 and have been used in some Iraq and Afghanistan operations but until now have not been available to all soldiers. The new ACUs will be good for about 50 launderings, but it is important to note that the uniforms should be washed separately from other clothing. There will be a permethrin-free ACU available for those with medical conditions, including pregnant women, who should not wear the treated uniforms. For more information check out these FAQs or contact the Armed Forces Pest Management Board.
Why has the F-22 Raptor been depriving its pilots of oxygen for the last 12 years? Air Force officials recently told a House subcommittee hearing (a complete video of the two-hour hearing is also available) that they don’t know what’s behind the dizziness, confusion, blackouts, memory loss, fatigue, and eventually chronic cough (“Raptor cough”) that pilots experience while flying the stealth jets. After more than a dozen incidents between 2000 and 2011—and one fatal crash—where pilots were being choked by the plane, the Air Force’s entire F-22 fleet was grounded in May 2011.
Investigations ruled out low blood sugar and dehydration as possible causes of the symptoms and eventually concluded that the problem was an overinflated pressure vest that restricted breathing.
In response, a team of NASA engineers and Navy divers developed a new-and-improved pressure suit and back-up oxygen systems and removed a faulty charcoal air filter. These measures seem to have alleviated the problems—a dozen F-22s recently were deployed to Japan without incident. Now restrictions are being lifted, although the jets and their pilots are being closely monitored. Pilots currently must operate under altitude ceilings so that they don’t need to use the flight vests, and they must also stay close to emergency landing sites. Experts and scientists continue to investigate the primary cause of these incidents as well as improve safety and back-up systems.