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
Before 2013 comes to a close, the Navy will begin distributing Flame Resistant Variant (FRV) coveralls to all Sailors assigned to surface ships and aircraft carriers. Previously, only Sailors working in engineering departments, on flight decks, and in other high-risk areas were issued flame-resistant clothing. However, a recent review found that the highest risk of severe injury from flames was from major fires or explosions, which puts any Sailor at risk. Tests revealed that the Navy Working Uniforms (NWU) type I, made of a polyester cotton blend, are susceptible to melting in a fire, which could cause even greater injury to the wearer. The new FRV coveralls are 100% cotton with a fire-resistant coating, which is self-extinguishing. The Navy plans to improve and standardize all coveralls over the next couple years by combining the protective effects of flame resistance, arc-flash protection, and low-lint specifications into one safe and effective uniform.
Veterans who served in the U.S. and abroad between September 2001 and March 2010 were four times more likely than civilians to suffer from severe hearing loss. In fact, two of the most common disabilities affecting service members today are hearing loss and tinnitus, says the Hearing Center of Excellence (HCoE). Hearing loss and tinnitus seriously impact force readiness as well as the emotional and social well-being of those affected.
However, not all hearing loss results from the noise pollution Warfighters experience in the field. Many everyday exposures, such as your MP3 player or loud music in your car, can be just as damaging as firearms or helicopters. To maintain good hearing and operational readiness, Warfighters must use safe listening practices at all times. HCoE recommends these safe listening practices:
- Never listen to your MP3 player at maximum volume.
- Following the “60:60” rule: 60 percent maximum volume on your MP3 player for no more than 60 minutes a day.
- Take periodic breaks of 15–20 minutes when listening to loud music to allow your ears to recover.
- Select headphones or earbuds designed to remove background noise.
- Exercise caution when listening to music in the car. Listening in a confined space increases the risk of hearing damage.
- Wear hearing-protection devices such as earplugs at concerts, sporting events, parades, and other high-noise situations.
For more information on how to protect your hearing, as well as treatment and rehabilitation for hearing loss, please read this article from HPRC and visit HCoE.
Compression garments are becoming more and more popular in the sports world. Back in 2001, NBA All-Star Allen Iverson began wearing a sleeve on his arm to help with bursitis in his elbow, helping to increase blood circulation and reduce swelling in his arm. Similar sleeves are used for clinical conditions such as lymphedema, where blood circulation is poor, or to prevent blood clots.
You can find compression garments as sleeves, socks, shorts, or even full-body suits. There are various levels of compression for garments, but they all have gradient pressure, which means they’re a little tighter at the bottom of the garment and a little looser at the top to help push blood toward your heart and prevent blood from ‘pooling’ or remaining in the compressed areas. Most garments need simple measurements around your arms or legs to make sure you have the correct size.
But can these garments also impact your performance and recovery? It’s been found that compression garments do actually help with blood flow and increase oxygen to working muscles. But whether that translates into improved performance is another question altogether.
Most performance-related studies have looked at the effects of compression sleeves or socks on running. Some participants said they didn’t feel they were working as hard when wearing compression garments on their legs. While the relationship between compression garments and performance is still not clear, some researchers have suggested that this psychological benefit of lower perceived exertion might help athletes train at higher intensity. However, more research is needed to show if this ultimately leads to actual performance improvements.
In terms of recovery, more research is needed too. The effects of compression garments on muscle soreness after exercise have been mixed, but there have been no studies on the use of compression socks or sleeves for shin splints and other leg pain. They are sometimes effective at reducing the muscle soreness that occurs 24-48 hours after exercise. Relief of symptoms from wearing these garments varies from person to person, sometimes with no benefit. And it isn’t clear whether wearing these garments during recovery will improve your performance next time.
The Human Performance Resource Center is here to serve Warfighters and their families, commanders, and healthcare providers. If you’ve visited before, you probably know that we focus on “total force fitness.” But do you really know what that means—or how HPRC got started? If you’re curious, check out this PDF that describes HPRC, what we do, and the vast amount of information we cover. In addition, you may have noticed that we use the term “human performance optimization” throughout our site; this article also explains what that means.
Prosthetic limbs have come a long way in a short amount of time, mostly because of the number of service members coming back from deployments with traumatic injuries and with the demand for better technology. Advancements in prosthetic arms now include devices that can move and bend individual fingers and joints. However, a sense of touch is one remaining obstacle—but one that researchers are close to conquering.
Many patients with arm prosthetics describe the difficulty with grabbing objects because there is no feedback to the brain. For example, breaking dishes, bruising fruit by grabbing it too hard, and dropping slippery cans are all too likely without any sense of feeling in the hand.
Researchers are now developing a prosthetic limb—called the Modular Prosthetic Limb—that will close the loop between the brain and the prosthetic hand by adding various sensors to contact points such as the fingertips and joints. This will allow sensory feedback to the brain that gives the user enough “feeling” to distinguish between a wool sweater and a cold beverage, for example.
The Department of Defense is working with various universities such as Johns Hopkins and the University of Pittsburgh to develop this unique device and make it available to wounded warriors.
Walk into any fitness center on base or take note of a group of soldiers training, and you’ll probably notice at least a few people in form-fitting synthetic t-shirts. The sports apparel industry has exploded in popularity over the past decade, with numerous manufacturers now competing to develop, market, and sell the newest pieces of clothing (shirts, shorts, underwear, socks), all geared to keep athletes cool while competing or training in hot environments. Is there any science behind these claims? Does tight-fitting clothing made of “high-tech” materials actually help with heat regulation and enhance athletic performance?
You heat up when you exercise, and sweating is the primary method your body uses to stay cool. Sweat evaporating off your skin is the most important method your body has to cool itself during exercise. High-tech materials are supposed to enhance “wicking”—the delivery of sweat away from the skin surface toward the clothing, which allows for evaporation—and limit the absorption of sweat by the clothing itself. Cotton, by contrast, absorbs moisture, so it’s not considered a good choice for exercise.
To date, there’s no evidence that this high-tech clothing improves thermoregulation when worn during exercise in hot environments. Specifically, researchers found no differences in heart rate or body and skin temperatures when subjects performed repeated 20–30 minute bouts of running outfitted in shorts, sneakers, and either a form-fitting compression or traditional cotton t-shirt. Research has also found that wicking sportswear had no effect on cooling when worn under a bulletproof vest or on a cycling sprint when worn under full ice hockey protective equipment. As of now, the best advice for staying cool during exercise in the heat is to wear lightweight clothing, stay properly hydrated, and listen to your body for signs of potential heat illness. For more information on performing in hot environments, please visit the “Heat” section of HPRC’s Environment domain.
Performing physical activity—whether exercise or mission demands—at moderate (4,000–7,900 ft or 1,200–2,400 m) and high (7,900–13,000 ft or 2,400–4,000 m) altitudes can be challenging. At high altitude, oxygen pressure is lower, which results in less oxygen in the blood and muscle tissues. And as altitude increases, there’s a decrease in air temperature (about 2°F for every 500 ft or 150 m), less moisture (resulting in drier air), and increased solar radiation. Use sunscreen, drink plenty of water, and watch out for the signs of acute mountain sickness: headache, nausea, shortness of breath, and impaired cognition and balance.
To learn more about altitude sickness, read the article “The Invisible Enemy of the Afghanistan Mountains” on the United States Army Research Institute of Environmental Medicine (USARIEM) website. And learn more about performance at altitude in the Altitude section of HPRC's Environment domain.
With current and future military operations in mountainous regions, the issue of acute mountain sickness (AMS) is a significant medical concern. AMS can affect anyone, military or civilian, who is unacclimatized and/or ascends too rapidly to high altitudes. Symptoms of AMS can include headache, nausea, fatigue, dizziness, and sleep disturbances. Recently, researchers at USARIEM were able to predict the severity and prevalence of AMS after rapid ascent to various altitudes. What they found was that for every thousand-meter increase in elevation over 2,000 m, a person was over four times more likely to develop AMS. In addition, the severity of sickness doubled, and the odds that the AMS would worsen increased almost five-fold. AMS appeared to peak at 18 to 22 hours of exposure to altitude and then went away after 42 to 48 hours. The severity of sickness is greatest above 4,000 meters and may require evacuation to lower altitude or immediate medical attention. It also appears that men are more likely than women to get AMS and more likely for it to be severe. For both men and women, the more active they were at altitude, the longer it took to recover. These findings support current recommendation to limit activity as much as possible in the first 24 hours at altitude to decrease the risk for AMS.
This information should help military leaders manage and perhaps prevent AMS among troops by knowing the elevation, types of activities, and lengths of stay at altitudes.
In order to reduce the risk for AMS, acclimate to moderate elevations (2,000 – 3,000 m) if/when possible. In addition, stay hydrated and try to limit your physical activity at altitude for the first 24 hours. Read more about the effects of altitude on performance and how to minimize your risk for AMS.
Giant hogweed—no, it’s not an ingredient in one of Harry Potter’s potions; it’s a large poisonous plant that started to bloom in the northeast and northwest areas of the U.S. and parts of Canada earlier this month. If you’re out for a ruck march through the woods and you come across this plant, do not touch it. The sap can cause irritation and burns to your skin and perhaps blindness if it gets into your eyes. If you do happen to come in contact with it, be sure to wash your skin with soap and water and keep the area out of the sunlight for 48 hours. Giant hogweed can grow 14 feet or higher. It’s characterized by large leaves and white, umbrella-shaped flower clusters at the top of the plant. It may be difficult to distinguish from other non-poisonous plants such as cow parsnip, so err on the side of safety if you’re not sure. You can read more about identifying invasive species in your area from the U.S. Department of Agriculture.
Your sunscreen has an expiration date—have you checked it lately? It’s meant to last up to about three years; after that, the active ingredients start to deteriorate, making it less effective and leaving you vulnerable to sunburn and sun damage. Ideally, you should be using your sunscreen often enough that a bottle doesn’t last through the summer. If that’s not the case, check the bottle you’re currently using—if it’s old, throw it out. If you buy sunscreen that has the expiration printed only on the box or wrapper, write the date somewhere on the bottle itself with a permanent marker. Practice safe sun this summer to keep you and your family healthy and happy!