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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

Runners: Hot taper can improve endurance performance

HPRC Fitness Arena:
Runnersworld.com has an article that cites a new study from the Journal of Applied Physiology which reports that 10 days of extreme heat acclimation can improve performance by six to eight percent.

 

runningman_shutterstock.jpgPhoto: Shutterstock.com

Runnersworld.com has an article that cites a new study from the Journal of Applied Physiology which reports that 10 days of extreme heat acclimation can improve performance by six to eight percent.

Click on link below to access article.

New Study–A Hot Taper Can Improve Endurance Performance

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Keeping fit while deployed at sea

HPRC Fitness Arena:
Marines and sailors rely on creativity and enthusiasm to keep fit while at sea.

Aircraft carrier close up

Keeping physically fit is an important part of a military career. Aboard the USS Kearsarge Marines and sailors merge creativity and enthusiasm to push their physical fitness to even higher peaks. The October 05, 2010 edition of Military Health System News has an article on how Marines and sailors aboard the USS Kearsarge find ways to supplement their physical training while at sea.

Read the full article here.

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Fluid replacement during operations or exercise

HPRC Fitness Arena:
There's a right way to replace the fluids you lose when you sweat.

If you sweat a lot during exercise, be sure to drink lots of fluids – but do not exceed 1.5 L/hour. Sip frequently rather than gulp; drinking small amounts of fluids at a time are more effective than drinking large amounts occasionally. Also, start drinking before you become thirsty. Click here for more information.

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How to help your skin survive the summer sun

HPRC Fitness Arena:
Summer sun can damage your skin.

Whether you are working out or relaxing, the summer sun can damage your skin. The American Academy of Dermotology recommends that you use a sunscreen of SPF 15 or higher, apply 15 to 30 minutes before going outdoors, and reapply every two hours. Make sure to cover all of your skin and use even if it’s cloudy outside.

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Protect your skin from the sun

HPRC Fitness Arena:
With the hot sun of summer, make sure your skin is protected when exercising outdoors.

With the hot sun of summer, make sure your skin is protected when exercising outdoors. This isn't just a cosmetic issue, but a health issue, as well. Apply enough sunblock of the correct type for the exercise you're performing outdoors. Visit Environment, Health, and Safety Online for general sun safety tips.

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Stay cool and in shape!

HPRC Fitness Arena:
Fitness and fun – swimming gives you both.

Swimming is a great way to stay cool this summer and get a great workout. Try variations with strokes and swimming equipment like kickboards and fins. For more swimming tips to improve your fitness, visit Medicinenet.com.

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Preventing heat-related illness

HPRC Fitness Arena:
What to drink when you're working out in hot environments.

When performing physical activities in the heat, avoid drinking liquids that contain alcohol or large amounts of sugar since these actually cause you to lose more body fluid. Also avoid very cold drinks, because they may cause stomach cramps.

Click here for the Center for Disease Control and Prevention's article on Emergency Preparedness and Response.

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What is heat acclimatization?

HPRC Fitness Arena:

For a more detailed analysis on heat acclimatization, click here.

Background

Heat-related injuries are a significant threat to the health and operational effectiveness of military members and their units. The human body’s response to heat stress is quite resilient if given several weeks for adaptation to occur. This process, called acclimatization, involves internal adjustments, in response to the outside environment, which improve heat tolerance. This adaptation can be fully achieved after 10 to 14 days of exposure to heat, but two-thirds, or even 75 percent, of the adaptation takes place within five days.

Myths and/or Claims

1) It is commonly believed that warfighters who are physically fit do not need to be heat acclimatized.

2) It is also assumed that older individuals are less heat tolerant than their younger counterparts.

3) Women are thought to need longer acclimatization time, since they are more vulnerable to heat illness.

Facts

1) Though fit warfighters acclimatize faster than less fit warfighters, a physically active person cannot be fully acclimatized without exposure to environmental heat stress.

2) Age has no effect on acclimatization. Research that controlled for body size and composition, aerobic fitness, hydration, degree of acclimatization, and chronological age showed little or no age-related decrements in one’s ability to manage or acclimate to extreme temperatures.

3) Nor does gender appear to be a factor: women were thought to need longer acclimatization, since they are more vulnerable to heat illness. However, women and men show equivalent thermoregulation during exercise when levels of fitness and acclimatization were controlled.

4) Heat-related injuries such as exertional heat illness remain a major cause of illness and occasional fatalities within the Armed Forces. However, as mentioned earlier, the human body’s can be resilient to heat stress if given several weeks to adapt.

Caution

Heat acclimatization adaptations may vanish after only a few weeks of inactivity (i.e., 18-28 days). The first adaptations to degrade are those that develop first: heart rate and other cardiovascular variables.

Summary for Military Translation

Studies have shown that acclimated soldiers suffer no detrimental effects of exertional heat stress, despite almost the same degree of heat strain. The Technical Bulletin-Medical 507 provides an evidence-based preventive program to protect military personnel from heat stress and associated adverse health effects. The recommended heat acclimatization strategies are to mimic the deployment climate, ensure adequate heat stress (i.e. by invoking sweating, having 4 to 14 days of heat exposure, and maintaining the daily duration of at least 100 minutes). It is also suggested that heat acclimatization start at least one month before deployment; and upon arrival, acclimatization should start slowly and build up by increasing heat and training volume as tolerance permits.

References

A.Nunneley, S. (2009). Prevention of Heat Illness Medical Aspects of Harsh Environments, Volume 1: U.S. Army Medical Department's headquarters

Armstrong, L. E. (Ed.) (1998) Encyclopedia of Sports Medicine and Science.

DOD. (2010). Update: Hear Injuries, Active Component, U.S.Armed Forces, 2009. Medical Survillance Monthly Report, Vol.17.

Lugo-Amador, N. M., Rothenhaus, T., & Moyer, P. (2004). Heat-related illness. Emerg Med Clin North Am, 22(2), 315-327, viii. doi: 10.1016/j.emc.2004.01.004S0733862704000057 [pii]

McArdle, W., Katch, F., & Katch, V. (2007). Exercise physiology. Energy, Nutrition & Human Performance (Sixth ed.): Lippincott Williams & Wilkins.

Radakovic, S. S., Maric, J., Surbatovic, M., Radjen, S., Stefanova, E., Stankovic, N., et al. (2007). Effects of acclimation on cognitive performance in soldiers during exertional heat stress. Mil Med, 172(2), 133-136.

USACHPPM. (2003). Heat stress control and heat casualty management.

 

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After heatstroke, when is it safe to exercise?

HPRC Fitness Arena:
Heatstroke is a potentially deadly consequence of exercising. "This is a very controversial area, even more so than concussions," said Dr. Francis G. O'Connor, president of the American Medical Society of Sports Medicine. He moderated a debate on the topic at a recent meeting of the American College of Sports Medicine.



From the June 15, 2010 edition of the New York Times.

Heatstroke is a potentially deadly consequence of exercising. "This is a very controversial area, even more so than concussions," said Dr. Francis G. O'Connor, president of the American Medical Society of Sports Medicine. He moderated a debate on the topic at a recent meeting of the American College of Sports Medicine.

See the full text of this article.

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Performing at your peak in high altitudes

HPRC Fitness Arena: Environment, Total Force Fitness
Researchers at USARIEM conduct research on military performance in high altitude environments and published their findings in Altitude Acclimatization and Illness Management Guidelines this year.

Researchers at USARIEM conduct research on military performance in high altitude environments and published their findings in Altitude Acclimatization and Illness Management Guidelines this year.

Their recommendations? Staying hydrated, healthy eating and refraining from smoking helps Warfighters to perform in high altitude environments. Click here for more information and recommendations for performing optimally in high altitudes.

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