The U.S. Marine Corps has purchased over a hundred portable physical exercise systems (or “tactical training lockers”) so that marines in a combat zone can continue exercises that keep them in the best condition for combat. In effect these lockers are portable gyms. This idea was developed by a former SEAL who went on to develop an exercise system (total resistance exercise, or TRX) optimized for combat troops. Normally the equipment needed is found in gyms on military bases and, for marines, aboard the amphibious ships they often use. But when stationed in Iraq, Afghanistan or somewhere else away from a base, the lockers allow training to continue. The lockers vary in size from a $5,000 unit that literally is the size of a locker to a $25,000 “locker” that travels in a standard 20 foot shipping container.
TRX is not considered recreation but preparation for the changing rigors 21st century ground combat. Since September 11, 2001 a lot has changed for infantry type combat. Troops carry more weight (especially protective gear) and new equipment. New tactics and situations require more speed and physical flexibility to succeed with. As a result new physical training routines were developed that enhance speed (which is used more in combat, as in sprinting for cover or a new firing position), flexibility (lots of squirming around in combat, going through windows or over obstacles) and strength (troops are carrying more weight, and there's always been a lot of heavy lifting in combat.) What is deemphasized is long marches (trucks and helicopters have made that rare) and distance running (another very infrequent demand these days). The new training strives to make troops stronger and more flexible. Another goal was to make it easier for troops quickly recover from physical stress. The weight training exercises and things like TRX helped.
One problem being addressed by the new training and systems like TRX is the long term muscle and bone damage from carrying heavy weights of weapons, armor and equipment into battle. All this was the result of the infantry getting a lot more money for new weapons and equipment since 2001. And there has been a lot of new stuff that the troops found useful. New armor provided more protection. New radios were lighter and more reliable (often with every soldier in a unit having one.) New sensors enabled troops to not only see at night, but also in sand storms (using thermal sensors.) A lot of the new gear was electronic and troops found themselves carrying more and more batteries. The heavy weights carried, often during vigorous combat activity, has led to more severe injuries developing earlier. For example in 2008 257,000 U.S. Army troops suffered "acute orthopedic injuries" and that was a four percent increase over 2007. In those two years more than 500 of those injuries were so severe that the soldier was no longer physically fit for combat.
What was new was the sharp increase in severe orthopedic injuries. For decades, combat soldiers have been shifted to less strenuous jobs when they suffered permanent muscular or skeletal injuries from combat, or even peacetime, operations. But now the numbers are so high that there are not enough other jobs for disabled (for the rigors of infantry combat) soldiers. Paratroopers, or even airmobile infantry who jump a few feet out of helicopters while carrying a hundred pounds of gear, often suffer permanent back or other injuries. Tank crews suffer similar risks jumping off their tanks, or overexerting themselves pulling maintenance on their armored behemoths. Just training for combat is a very physically demanding task.
The main problem is that American infantry are carrying too much weight. It's a problem going back thousands of years, and few armies have been able to solve it. Cutting the weight is difficult, mainly because a lot of the new stuff is either very useful to the troops or else something lobbyists, manufacturers, politicians and the media would make an issue of if it were cut. One solution that helps a lot, and is not politically incorrect, is new exercises and the portable weight room for use in a combat zone.