Welcome to the HPRC Blog. We've got lots of information here, from quick tips to in-depth posts about detailed human performance optimization topics.
HPRC Fitness Arena: 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.
Barefoot-style, or minimalist, running shoes are still growing in popularity in the military, and the debate continues over whether this style of running prevents injuries or just causes different injuries. There is new research on minimalist running shoes (MRS) and their impact on lower leg and foot injury. After a 10-week study, runners who transitioned to Vibram FiveFinger minimalist running shoes showed signs of injury to their foot bones, while the runners who used traditional running shoes showed none. The types of injuries the MRS runners demonstrated were early signs of inflammation, which may or may not be associated with pain or joint dysfunction. If they are, it might be difficult for the runner to know he/she is actually injured until it is too late and the injury has progressed. More research is needed to determine if other factors (weight, running form/style, mileage, running surface) contribute to injuries associated with barefoot-style running. At least one recent study suggests running style may be a factor. For more in-depth information, read
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.
The annual Army “Strong B.A.N.D.S.” campaign is set to launch for another year beginning in May. Strong B.A.N.D.S. promotes physical fitness, nutrition, optimal health, and resilience by focusing on Balance, Activity, Nutrition, Determination, and Strength—forming the acronym B.A.N.D.S. The campaign has activities at numerous garrisons to help educate soldiers, their families, and civilians. Strong B.A.N.D.S. is a campaign of the U.S. Army Installation Management Command Family and Morale, Welfare and Recreation directorate and is “designed to energize and inspire community members to live a healthy lifestyle.”
Check out the website for detailed information and to see if there is a Strong B.A.N.D.S. activity near you.
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.
Physical and mental rehab for wounded warriors can come in the form of an undersea adventure. A 2011 study at Johns Hopkins University looked at the effects of a four-day scuba certification class on a group of veterans with spinal injuries. The benefits noted included improved muscle movements, reduction of post-traumatic stress disorder symptoms, and improved sensitivity/sensation for those with certain spinal cord injuries.
Being in the water offers a zero-gravity environment that enables Warfighters to develop the confidence and ability to do activities they may not feel comfortable doing on land. There are organizations that provide scuba lessons and outings for wounded veterans and their families free of charge, such as Adaptive Heroes, Soldiers Undertaking Disabled Scuba (SUDS), and Divers4Heroes, to name a few. Check for programs in your area and explore the great unknown!
Army researchers have developed a special method of meal delivery for U-2 pilots on long flight missions, which can sometimes last up to 12 hours. Pressurized suits and bulky equipment limit pilot movement and prevent them from opening their helmet visors—so feeding themselves until now has been impossible. Chefs and nutritionists in Natick, MA, teamed up to create meals that meet a pilot’s calorie and nutrition needs. The meals are turned into a consistency similar to baby food and delivered to the pilot by way of a metallic tube about the size of a tube of toothpaste. The containers fit into a port on the pilot’s helmet in a way that doesn’t interfere with the suit’s pressure. Watch this video to see these tube meals in action!
What are the favorites among pilots? Caffeinated chocolate pudding and chicken-à-la-king are the most popular. Other meals include beef stroganoff, key lime pie, applesauce, and sloppy joe.
Total Force Fitness requires optimal performance, and optimal performance requires optimal sleep. One way to get your best sleep may lie in some of the subtle sounds you hear every day. You may have heard of “white” noise, a type of random, constant sound that can filter or mask surrounding noises. Studies have now found that another kind of sound—“pink” noise—can help your sleep be even more restful than actual silence. Unlike white noise, the volume of pink noise is essentially the same regardless of its frequency. (For serious audio buffs, here’s an explanation from Georgia State University’s “HyperPhysics” department.) When you think of pink noise, think of rain falling or the rhythm of a heartbeat. This kind of noise regulates and synchronizes with your brainwaves, which enhances the percentage of time you’re in a restful, stable sleep. Pink noise might be another strategy to add to your arsenal for getting better sleep. You can get recordings of pink noise from a variety of sources online—some even free—for your smartphone or other mp3 player or cd/dvd player. A little searching should turn up something you like. And read more about the importance of sleep and how it affects your performance.
Hiking is a great form of exercise and a great way to get outdoors and enjoy some scenery—especially when getting ready for deployment to challenging terrain. If the weather outside is less than ideal, however, or the winter temperatures become too frigid, you may need to move your hiking indoors to a treadmill. Keep in mind that you might not be working as hard on a treadmill as you would be hiking outside at your regular pace. Hiking requires different, often heavier footwear and involves a more diverse, varied terrain, both of which require more energy than walking in sneakers on a treadmill. If you want the same benefits, your treadmill needs to be set to at least a 3% incline for any speed up to 3.1 miles per hour to be comparable to what you expend hiking outside. You can still train for that mountain trek in bad weather—you’ll just need to make some slight adjustments. Happy trails…or treadmilling!
Motion sickness can affect even the strongest Warfighters. Nausea, vomiting, dizziness, and sweating are some of the telltale signs of kinetosis, or motion sickness. The potential impact on individual and force readiness make it a concern in military medicine.
Motion sickness may affect individuals differently, but generally it follows a pattern. The earliest symptom typically is abdominal discomfort. If the motion continues, discomfort is usually followed by overly warm sensations, nausea, and wanting cool air.
Motion sickness can be alleviated to a degree by following these simple tips:
- Pick a seat where motion is less likely to be felt, such as an aisle seat on a plane, a central cabin on a ship, or a car toward the front of a train.
- Avoid sudden movements of the head, which can aggravate motion sickness.
- Avoid tasks that involve prolonged close-up eye movement or focus (such as reading a book). Focus instead on the road in front of you or on a distant object so that your senses can confirm that you’re on the move.
- Avoid alcoholic beverages before and during a trip, as alcohol can worsen motion sickness.
- If possible, expose yourself to the motion in gradually and in stages until you adapt to the movement.
Jerome Greer Chandler, a former combat medic, describes the severity of motion sickness among U.S. service members in an article to The American Legion Magazine [PDF]. For a detailed reading on motion sickness and its effect among military personnel, see the Textbooks of Military Medicine (volume 2).