FORT RUCKER, Ala. -- In his ancient military treatise "The Art of War," Sun Tzu notes that if you put your army on a forced march at a certain speed, you will lose one-tenth to two-thirds of your troops along the way.

While technology has progressed quite a bit in the 2,400 years since Tzu's day, the effectiveness of troops who march long distances with their equipment remains a critical factor in the success of many military operations.

During dismounted troop foot movement, Soldiers must carry heavy equipment over varying terrains with multiple environmental hazards. Heavy loads can lead to rapid fatigue, greater food and water requirements, awkward body postures, and stress and friction to body parts.

The costs are well documented by both scientists and military historians. These factors reduce a Soldier's physical and mental combat performance capabilities and increase the risk of injury. The results can be fatal for individuals and detrimental to a unit's mission success.

The ability to effectively and rapidly move troops by foot is an indisputable advantage in many operational circumstances, which is why foot march training, or "rucking," remains an important component of Army readiness training.

Foot march training that is too excessive or intense, however, can unnecessarily increase the risk of acute and overuse injuries. The injuries can lead to recovery periods and medical treatment that limit physical activity for days, weeks or months, and could even cause permanent disability.

Though training to fight will always be associated with some risk of injury, the Army can train smarter. Various military studies and observations echo this concern:

-- Foot march training was found to be five times more hazardous in terms of injury rates than regular physical training.

-- Foot marching was reported as the second-leading cause (next to running) for training-related injuries in IET trainees and a non-deployed infantry unit.

-- Ruck running may increase injury risk, so speeds should not exceed 3 to 4 mph.

-- Programs that don't include adequate non-marching activities to increase overall physical fitness may have higher injury rates. Some training programs have optimized performance by including a mix of loaded foot marching with non-march upper-body resistance physical training and aerobic training.

-- Training programs that increase the intensity (load weights) and distance (time) too quickly can increase injury risk. A general rule is to not exceed a 10 percent increase in intensity or distance on separate days weekly.

INJURIES OF CONCERN

Foot marching-related injuries can occur in almost any part of the body, but the vast majority occur in the back and lower-extremities, including the legs, knees, ankles and feet. Most injuries result from the repetitive stresses placed on the body's skin, bones, muscles and nerves.

Environmental conditions can also contribute to the risk of injury. Rough terrain can lead to acute sprains or fractures from slips, trips and falls. Heat stroke, heat exhaustion and heat cramps are a concern given the hydration needs of personnel wearing body armor and carrying heavy gear. Cold weather, altitude, and animals can also cause injuries.

Severe musculoskeletal injuries like ankle fractures or sprains or stress fractures can require extensive medical care and result in months of lost duty time or even a medical discharge. Stress fractures in the pelvis, which have been found more frequently among female recruits, require an especially long rehabilitation period.

Some injuries, such as ruck sack palsy, a specific shoulder nerve compression condition, are uniquely associated with ruck marching. Other overuse injuries may not be attributable to foot marching activities alone. For example, stress fractures of the hip, leg and foot and knee injuries may be exacerbated by running.

WHAT'S THE SOLUTION?

Unfortunately, technology alone cannot solve the age-old problem of heavy loads. Over the last century, despite the weight reduction of some items and advances in individual protective equipment, munitions and communication systems have contributed to an increase in the average weight of carried loads.

Other "heavy" supplies, especially water, simply cannot be replaced. The loads carried in recent operations in the Middle East have been reported to average more than 100 pounds.

Unit leaders should consider the following suggestions to both optimize performance and minimize injuries:

-- Review injury risk factors and possible prevention tactics.

-- Encourage Soldiers to modify individual factors within their control.

-- Plan and document the unit's foot march training program purpose, necessary distance(s), equipment and weights, speed(s), terrain and environmental factors, and progression goals and dates for each training session.

-- Ensure physical training regimens avoid consecutive days of intense lower extremity training such as distance runs and foot marching.

-- Be aware of the unit's injury rates and the types of injuries experienced to adjust training regimens as needed.

-- Consider coordinating with master fitness trainers or physical therapists to establish and plan a training program that is best suited for a specific unit.

TRAIN TO FIGHT SMART

The Army's primary investment is in developing and maintaining Soldiers who are physically and mentally ready to fight our wars. Rigorous physical training is a necessary and unavoidable component of this investment, and with it there will always be some risk of injury.

However, many injuries are not an acceptable part of "doing business." Nor should they be a way to "weed out the weak." Unit leaders should assess their foot march training programs and apply prevention measures to help minimize injuries.

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(Editor's note.) This piece has been edited for length and style. You can find the original here: https://safety.army.mil/MEDIA/Knowledge/TabId/97/ArtMID/478/ArticleID/518/The-Weight-of-War.aspx