Winston Salem Fitness

Progression: Progression is perhaps the most important concept to minimize the chance of an overuse training injury. The body adapts to the things that it does regularly and allows gradual improvements in performance. For instance, the reason that new recruits, and not the drill sergeants, are usually injured in basic training is that the sergeants have been performing the activity for months or years and their bodies have adapted to it. That is, any individual who has exercised for a long time is probably going to be able to continue that activity without significant difficulty.

Individuals get into trouble when they change their program to either do more or train at a higher intensity, or are attempting to come back after a layoff. Dr. Smith, advocates a 10-percent rule for minimizing the chance of injury. Smith says, “Each week, there should be no more than a 10-percent increase in the amount of training time, amount of distance covered, and number of repetitions performed in your activity. If you increase your intensity, don’t increase your distance. Although no controlled study has as yet defined the optimum safe training progression for an athlete to follow, but adhering to the 10-percent rule makes good sense.”

This concept is tied to the familiar exercise prescription which recognizes three variables that describe virtually all activities: 1) duration, 2) intensity, and 3) frequency. The chance of an injury increases dramatically when any of these are individually increased by more than 10 percent in a given week. Additionally, the total exercise exposure, expressed by the product of duration, intensity, and frequency, should not increase by more than 10 percent for any given week.

This may actually be a liberal rule of thumb, if the advice of a legendary Oregon track coach is considered. Bill Dellinger’s solution for his elite track athletes was 10 percent a year! About Dellinger, Runner’s World correspondent Bob Wischnia states, “That may be one reason Dellinger’s greatest runners, such as Steve Prefontaine, Alberto Salazar, and Ken Martin, didn’t peak until after graduating from college. The 10 percent solution is even more applicable to midpack runners. It reduces the risk of injury and allows plenty of time to get stronger and improve.” All of these variables interact with each other and a change in one causes an impact on the body which will result in slow adaptation over time.

A second element associated with progression is “periodization,” a training cycle designed to deal with changes in intensity and duration. When intensity increases, duration decreases. Conversely, when duration increases, intensity decreases. Coaches have used periodization to enhance the performance of their track and field athletes, but it has now become a common training principle that can be adapted to most all exercise programs. Periodization increases the power of the 10 percent rule by providing additional time to recover.

While periodization programs appear in many forms, they all include a varied training stimulus and periods of planned rest. What most people associate with the 10 percent rule is that increments can be added week after week. This probably isn’t the best approach because some tissues need more time to adapt. Dr. (Col) Tom Scully, a surgeon at William Beaumont Army Medical Center, found that by backing off slightly about every third week during an increased phase of training, the incidence of stress fractures in bone decreased markedly. Meanwhile, the respite allowed recovery and bone growth to occur, which he states, “should be considered to be the skeletal goal of physical training programs.”

Specificity: Specificity deals with the type of activity included in a workout. It is clear from a decade of clinical research that every exercise is unique and there is not a great deal of crossover effect from one activity to another. It’s risky to assume that one type of exercise adapts you for all others. Therefore, from an injury prevention perspective, you should change your workout routine very gradually, if at all possible, and recognize that your limits refer to specific activities.

To illustrate, we can contrast two related (yet significantly different) activities of jogging and sprinting. Although both use the large muscles of the legs, they differ in both the specific muscle fibers used and the way these fibers are activated by the brain. Jogging is a slow, rhythmical activity, and “slow twitch” endurance fibers are called upon to perform this task. Sprinting takes big bursts of energy. It uses a specialized set of muscle fibers called “fast twitch” fibers which are specialized for strength.

Although a jogger may have trained these endurance fibers, the bigger, stronger fibers that are activated in a sprinting activity would not be receiving a significant training effect while jogging. An expert panel at Penn State cited this disparity, noting that it is fiction to think that “participation in aerobic exercise produces significant strength gains for the muscles involved. For example, the leg muscles of champion marathon runners clicking off repeated sub-five minute miles are not much stronger than age and gender-matched spectators lining their 26 mile course.”

This phenomenon explains why muscle pulls are so frequent in weekend athletes who attempt to play sports like softball or basketball. Sprinting activates a new group of muscle fibers and creates higher tension levels, which may overwhelm the muscle-tendon unit and result in a pulled muscle. To be prepared to sprint, the training program needs to be specific and include some sprinting.

Training needs to be tailored to meet the specific demands of the activity performed. Jogging is different from sprinting and these differences need to be recognized and respected. The bottom line is, be cautious when undertaking new activities, and provide the body with some time to adapt to the novel task.

Overload: Overload is the stimulus required for a positive training effect. This is most easily visualized with weight training, where an individual is pushing or pulling a given weight in an effort to make a muscle stronger. If the weight that is used is easy for the individual to move, and the muscle is not “overloaded” or tasked to work at a greater than normal level, there will not be a training effect.

For example, if an individual performs 20 push-ups a day, five days a week, at the end of the year that individual will be able to perform 20 push-ups. The outlined push-up program is adequate for maintenance, but it is insufficient for a positive training effect or improvement. In a similar fashion, with aerobic programs, when the goal is to increase the aerobic capacity or improve running speed, an overload is required to serve as the stimulus for this change. The interval training program discussed in this guide is an example of a training program that uses periods of overload mixed with the next component, recovery.

Recovery: Recovery is providing the time and environment for the body to adapt to the demands that have been placed upon it. As indicated earlier, the number one mistake is doing too much, too fast. Often, this drive is expressed in the adage “if a little is good, then more is better!” Recovery can take the form of an easy workout, or the well deserved day off.

It isn’t necessary to train every day with the same workout. For example, experts agree that the greatest benefit of aerobic exercise coincides with training just three days a week. Some small benefit exists for training up to five days a week, but beyond that, a point of diminishing or reversing returns is reached. Even world class athletes need recovery.

Bob Wischnia of Runner’s World describes a run with the one-time marathon world record holder, Rob De Castella. He writes, “I assumed everyone was running slowly out of politeness to me. Afterward, we retreated to a pub to blow the froth off a few, and I mentioned to Deek (De Castella) that he didn’t have to run quite that easy just for me. ‘I wasn’t running easy for you,’ Deek said, mildly irritated. ‘It was for me. When I run hard, I run very hard. But when I run easy, it’s extremely easy.’ Deek believed that the single greatest mistake most runners make is to run too hard on their easy days.” The lesson: build recovery into your exercise program.

Cross Training is another way to put some recovery into a training program. For a regular jogger, replacing a run with a session of swimming, cycling, stair climbing, or walking would be an example of crosstraining. The values of cross training are only beginning to be recognized, but they include keeping training interesting by adding variety, decreasing injury incidence by promoting recovery, and providing an invigorating workout while resting the muscles and joints normally stressed.

Consistency: Consistency is staying on track and insuring that the exercise activity is performed properly. When individuals become fatigued, their form will often deteriorate and stress will be placed on tissues which have not adapted to the demand. Remaining vigilant for proper exercise form will significantly assist in minimizing the risk of injury.

Winston Salem Fitness – The number one training error is overuse, or doing too much too fast. When the body is faced with a new task, it does its best to adapt to the challenge, but the adaptation takes time. Dr. Angela Smith, a Cleveland-based Orthopedic Surgeon, advises that “Training error leading to chronic injury is a major cause of downtime in sports. It takes time for the bones, tendons, and muscles of athletes to adapt to the stress of workouts. How much you train really comes down to being able to listen to your body and make adaptations in your workouts as needed.”

Overuse injury occurs because most people are totally unaware of the biomechanical stresses involved in simple exercise and ignore the toll on their body. It’s not surprising that 30 to 75 percent of all sports injuries are attributed to overuse. The team physician for the University of Washington, Dr. Stanley Herring, illustrates the problem by pointing out that “A 70-kg (154 lb.) runner at 1175 steps per mile absorbs at least 220 tons of force per mile.” That’s an incredible amount of pounding! With these types of cumulative forces, injury results from microtrauma, rather than from a single overwhelming event.

The common feature in these overuse injuries is not that the workout was inappropriate, but rather that the repetitive trauma overwhelmed the body’s ability to repair itself. Mistakes of performing too much, too fast, are extremely common with changes in season, activity, or changes in terrain. Common sense needs to be employed during training to provide an adequate mix of overload and recovery. When sound, positive, training techniques are employed, the vast majority of overuse problems can be avoided.

Training, properly structured, may be an example of “less is more.” Dr. Smith notes that while exercising, “Pains in your muscles or joints indicate that you’re doing too much, too soon. Cut back on your distance and intensity until you’re pain free.” The key to training properly is to have a reasonable progression, and recognize the need for overload, recovery, and consistency.

Other predisposing factors for injury can be grouped into personal characteristics and training characteristics. Personal characteristics are factors such as age, gender, experience with sport, previous injury, body composition, and psychological make-up. Training characteristics include items like warm-up, stretching, equipment, time of day, and the training program.

Since the personal factors are either not modifiable, such as age and gender, or are difficult to modify, they will not be considered further. Positive training principles are provided to address training characteristics and optimize the chance of remaining “in the fast lane.”

Winston Salem Fitness – It’s not always easy to listen to your body because the messages are sometimes unpleasant. There are mornings when simply getting out of bed seems a struggle, a bad idea, with small aches and pains in joints, tendons, and muscles. Anatomically, that’s the cost of aging. Maturity brings reductions in joint flexibility, elastic tissue, tendon blood flow, muscle mass, and bone mass.

Growing older challenges a “just do it” philosophy, yet the available evidence suggests that is exactly what should be done. Certainly, aches and stiffness shouldn’t be ignored, but it’s important to sort out pain symptoms that signify injury from those which are the normal consequences of an active lifestyle. That is, it’s necessary to listen for the different voices of aches and pain in your body.

As depressing as they first feel, normal aches tend to vanish with activity. They shouldn’t be an excuse to skip a workout. Minor stiffness that resolves with motion is also common and not necessarily indicative of a musculoskeletal problem. Likewise, a mild grinding or “crepitus” in a joint like the knee is often present in healthy adults, and does not usually signify a major problem unless the roughness is accompanied by pain, swelling, decreased range or motion, or pain was present for a half hour or more following the activity. In these cases (or anytime a problem is persistent), appropriate medical evaluation and treatment should be sought.

The reason a mild roughness under the kneecap might be present without pain is due to the way that the joint is constructed. The cartilage that is under the kneecap is thicker than anywhere else in the human body. This thickness is a good design because significant forces are generated under the kneecap; the thick cartilage assists with the dissipation of these forces. Over time, some wear and tear often occurs; however, the wear is “a normal part of aging…we all have it if we survive past the age of twenty-five,” according to Rheumatologist, Dr. John Bland.

You can feel this mild grinding sensation by placing a hand on your kneecap as you straighten your leg. The reason this usually doesn’t hurt is that cartilage lacks nerves to send pain signals to the brain. If, on the other hand, the wear and tear becomes excessive or other problems, such as tightness or muscle imbalances, result in abnormal alignment of the kneecap, excessive forces may be transferred to the underlying bone. Bone has a robust nerve supply, and when irritated, will inform the brain of a problem in the form of pain. As such, pain is really a beneficial thing, since it tells us when something isn’t working in an optimal fashion.

How about wear and tear on joints? Will exercise accelerate this process and destroy the joint? Do activities like running cause the most common type of arthritis? According to Dr. Bland, “In a word, no.” In over ten years of studies, medicine has not been able to establish a clear link between running and arthritis. In fact, the opposite is true. As Dr. Bland points out, “Exercise is the key to keeping tendons, ligaments, and bones strong”.

These are all structures that are affected by aging, and the exercise stimulus helps maintain these tissues at a functionally younger state. By contrast, “Complete immobilization of a joint for as short a time as three to four months will totally destroy a joint,” he explains. That is, the evidence to date suggests that the common “use it or lose it” adage fits for our joint structures.

This isn’t to say that running is for everyone or that everyone should run. The medical research in support of exercise assumes that a joint has not been injured in some way and is functioning normally. In cases where ligaments have been torn or the cartilage in the joint has been damaged or removed, the results may be quite different. Certainly, pain that is present during or after a workout is a message that another less stressful activity should be substituted.

But here’s another perspective: We don’t just build muscle when we exercise; we also build ligament, tendon, and bone. We nourish cartilage as well, and exercise helps us rebuild or “remodel” damaged tissue. Dr. Bland states, “We know today beyond any doubt that all connective tissues remodel according to the lines of stress. This is important, not just in dealing with injuries and optimizing athletic performance; It also points the way to surviving to a healthy advanced age with intact and functional connective tissue.”

Stiffness is another common problem of middle age. It can occur at rest or in motion from a variety of causes. It seems natural to let stiff joints take care of themselves, such as backing-off and resting. Actually, that response is counterproductive because it contributes to three common problems: tightness, delayed rate of healing due to diminished blood supply, and poor posture. The lesson is this: our musculoskeletal system responds to exercise in ways that heal, not harm, provided that we are sensible and listen to our bodies.

Some medical conditions can be predicted from the changes that gradually occur from aging and are aggravated by certain activities. For example, Dr. Douglas Tumen, a podiatrist writing about the aches and pains of running, states that, “Running has many benefits, but increased flexibility is not one of them. In fact, as running strengthens your leg muscles, it also shortens and tightens them.” This is one reason that foot and leg problems, such as plantar fasciitis and Achilles tendinitis are so common in athletes who run regularly.

Plantar fasciitis, the commonly experienced heel pain which is most pronounced upon arising in the morning, results from this type of shortening of a band of fibers on the sole of your foot, coupled with thinning of the shock- absorbing fat deposits near the heel. During the day, the tightened band is stretched and ultimately loosens up, but not without some damage to the band. Then at night, the band shortens again and attempts to heal.

Upon arising from bed, the shortened connective tissue is again stretched, tearing at the healing attempt that has occurred during the night and resulting in more pain. This condition can range from minor to disabling, especially when coupled with improper or aggressive training techniques.

Achilles’ tendon ruptures, like the one sustained by former Vice President, Al Gore, are also due to similar tightening coupled with a diminished blood flow. Over time, the shortened tendon also has less elastic tissue in it, further inhibiting its flexibility. This problem starts as an inflammation of the tendon on the back of the foot, which does not heal readily due to the relatively poor blood supply in one portion of the tendon. If unprotected stress continues, the stage is set for an activity limiting injury, such as a ruptured tendon.

The American College of Sports Medicine (ACSM) recommends that regular flexibility training be part of a well-balanced exercise program, in order to minimize the changes that occur with aging. To minimize the impact of these cumulative postural changes and adaptive shortening, a regular flexibility program is recommended as part of the exercise programs prescribed.

The reader may be familiar with a flexibility assessment examining the back, thigh, and legs, since flexibility is evaluated during the health and fitness assessments for the students passing through the U.S. Army War College. This assessment is a prelude for guidance on the need for stretching. What is known about stretching will be covered later in this section, as a component of a complete exercise program.

Prolonged postures contribute to other problems that often effect areas like the back, neck, and shoulders. Protracted sitting to write or type at a work station can result in a stance where the upper back is rounded, and the head and neck are positioned forward. This causes both connective tissue changes and makes muscles work overtime to support the head and neck against gravity.

Gradually, the connective tissue in regions like the front of the chest and upper neck undergo permanent shortening, while in other areas the connective tissue is stretched out, resulting in permanent “habits”. Also, the stretched muscles tend to weaken, much like a stretched rubber band is not as resilient as one of normal length. This contributes to the background noise of aches and pains. Fortunately, these connective tissue and muscular problems can be minimized by being aware of your posture and taking a few minutes throughout the day to stretch the kinks out.

In sum, while most anyone who enjoys an active lifestyle feels minor stiffness and muscle aches now and then, the evidence suggests that this shouldn’t limit a personal exercise program. Even individuals with documented arthritis can (and should) exercise, advises Dr. Gordon Matheson and colleagues at the University of British Columbia, who found that activity-related pain is usually not the underlying source of discomfort.

The real barrier for most individuals interested in participation in a regular exercise program is not minor aches and pains, but rather injury. Dr. Matheson’s work with adults in their mid-fifties has shown that illness and injury are the number one and two causes of inability to participate in an exercise program. Those barriers must be avoided to maintain a regular exercise program and reap its benefits. In addition, the fact is that injuries are largely caused by training errors

Winston Salem Fitness – According to Dr. Steven Fleck, Sports Physiologist for the US Olympic Committee in Colorado Springs, the key to physical performance as we age is to be consistent in our exercise programs. “If we de-train, it becomes very difficult to fight our way back into shape. Continuing an exercise program, even if it is a moderate one, is a lot easier than having to start all over.”

You know that an increased effort will be needed to maintain your training program if … “your knees make noises even your opponents can hear, your right elbow hurts and you are left-handed, and you try to plant your foot to change directions but continue running three more steps.” This spoof on competitive athletics appeared in Penn State’s Sports Medicine Newsletter.

While satirical, it still reflects the fact that aches and pains are the single greatest hazard to consistency in exercise programs, even for the most elite athletes. Without the benefit of coaches and trainers, however, non-athletes face a bigger problem keeping the pain from their gain. Furthermore, many assume that aches or muscle soreness are signals to stop altogether.

The health and performance benefits of a regular exercise program have long been acknowledged, but they don’t come for free; it takes regular workouts. Still, the more one trains, the greater the chance of injury. Therefore, the executive who recognizes that exercise is a key component to a healthy lifestyle must walk a fine line to stay in the fast lane. Doing so a big challenge because injuries are extremely common, while typical activity levels and regularity of exercise diminish with age.

Are aches and pains inevitable? Does exercise actually increase both the incidence and severity of these problems? Can anything be done to lessen the painful effects of a regular exercise program? How common are training injuries? Is there a time when the smartest thing is to mothball your running shoes?

Virtually everyone who exercises will experience aches and pains. The symptoms range from joint stiffness in the morning, to sore muscles following a previous day’s workout, to an injury which cannot be ignored. A recent article in Sports Medicine noted that among average recreational runners, “the overall yearly incidence rate for running injuries varies between 37 and 56%.” As sobering as these statistics are, there is a silver lining when the rest of the story is heard: The vast majority of injuries sustained by individuals participating in aerobic activities can be prevented!

Moreover, our musculoskeletal system is robust and can adapt to most all stresses encountered in training programs. In other words, with adequate, balanced overload of the muscles, tendons, ligaments and bones, all of these structures grow stronger and can withstand increased stress in the future. Therefore, the key to minimizing the chance of injury is to listen to your body and avoid common training mistakes.

Winston Salem Fitness – Depression and stress are not caused by a poor diet, but a link between food and mood can exist. When one becomes depressed, energy level and drive are much lower than usual. Enthusiasm for most things, including meals, is lost. Healthy eating practices can suffer as a result. Carbohydrates are an important component to a healthy diet to combat depression and should comprise 50-60% of daily intake.

Carbohydrates increase the brain’s production of serotonin which heightens feelings of well-being and mood. Carbohydrates come from plant foods like fruits, vegetables, beans and whole grains and also are supplied in milk. When under stress or depressed, avoid alcohol. Many people think alcohol makes them feel “good,” but it is actually a depressant. Consuming alcohol can contribute to nutritional deficiencies of vitamins needed for good mental health.

Long-term stress can cause damage to the body and increase risk of becoming ill. In addition, many people respond to stress by overeating. Prolonged stress can lead to chronic health conditions like heart disease, stroke, cancer or ulcers. However, studies have shown that eating a diet with plenty of fruits, vegetables, and whole grains is protective against the harmful effects of stress. Antioxidants and phytochemicals are substances found naturally in plant foods that can boost immune function and reduce the risk of disease.

Some top sources of antioxidants include broccoli, cantaloupe, papaya, spinach, asparagus, carrots, tomatoes and peaches. Foods rich in phytochemicals include tomatoes, romaine lettuce, pink grapefruit, sweet potatoes and soy products. To get the benefits of these important nutrients, eat at least 5 fruits and vegetables every day. Getting these important stressbusting nutrients has been shown to be more effective if taken in food form rather than supplement.

When stressed:

• Don’t binge or grab whatever is in sight. Take time for eating well.
• Include plenty of carbohydrate foods like fruits, vegetables, and grains.
• Limit caffeine and alcohol.
• Do something other than eating. Exercise can relieve some of that stress.
• Try quick foods and recipes. Order in if you have to, but don’t skip meals.
• Take time out for a healthful breakfast.

Source: CPT Sarah Flash, Registered Dietitian

Winston Salem Fitness – Exercise may improve mental health by helping the brain cope better with stress, according to research into the effect of exercise on neurochemicals involved in the body’s stress response.

Preliminary evidence suggests that physically active people have lower rates of anxiety and depression than sedentary people. But little work has focused on why that should be. So to determine how exercise might bring about its mental health benefits, some researchers are looking at possible links between exercise and brain chemicals associated with stress, anxiety, and depression.

So far there’s little evidence for the popular theory that exercise causes a rush of endorphins. Rather, one line of research points to the less familiar neuromodulator norepinephrine, which may help the brain deal with stress more efficiently.

Work in animals since the late 1980s has found that exercise increases brain concentrations of norepinephrine in brain regions involved in the body’s stress response.

Norepinephrine is particularly interesting to researchers because 50 percent of the brain’s supply is produced in the locus coeruleus, a brain area that connects most of the brain regions involved in emotional and stress responses. The chemical is thought to play a major role in modulating the action of other, more prevalent neurotransmitters that play a direct role in the stress response. And although researchers are unsure of exactly how most antidepressants work, they know that some increase brain concentrations of norepinephrine.

But some psychologists don’t think it’s a simple matter of more norepinephrine equals less stress and anxiety and therefore less depression. Instead, they think exercise thwarts depression and anxiety by enhancing the body’s ability to respond to stress.

Biologically, exercise seems to give the body a chance to practice dealing with stress. It forces the body’s physiological systems – all of which are involved in the stress response – to communicate much more closely than usual: The cardiovascular system communicates with the renal system, which communicates with the muscular system. And all of these are controlled by the central and sympathetic nervous systems, which also must communicate with each other. This workout of the body’s communication system may be the true value of exercise; the more sedentary we get, the less efficient our bodies in responding to stress.

Thanks to Rod K. Dishman, PhD, of the University of Georgia, and Mark Sothmann, PhD, of Indiana University’s School of Medicine and School of Allied Health Sciences.

Winston Salem Fitness – The activities we do every day, such as carrying groceries or picking up a child, require muscle strength and endurance. Although aerobic activities are effective for developing cardiorespiratory fitness, most aerobic activities have little influence on muscular strength. The American College of Sports Medicine (ACSM) recently recommended that adult fitness programs include moderate to high-intensity resistance training.

In addition to developing muscular strength, resistance training increases lean muscle mass, improves the strength of connective tissue, and increases bone mass. Other health benefits include reductions in body fat, modest reductions in blood pressure, improved lipid profiles, and possible injury prevention.

The key factor to successful resistance training at any level of fitness or age is appropriate program design. Supervision by a qualified professional is essential to prevent injury and to maximize health and performance benefits. Exercise instruction should include proper technique, breathing, and use of equipment, along with goal setting and progress evaluation.

The primary goal of the program should be to develop total body strength, endurance and mobility in a relatively time-efficient manner. Strength can be maintained in only one session per week and gains can be made with as little as two sessions per week. Each session need not be long. In fact, programs lasting longer than one hour per session are associated with increased injury. The ACSM recommends that resistance training be done two to three days per week. The program should include one to three sets of 8 to 12 repetitions. Exercises should focus on the major muscle groups of the upper and lower body, including:

• The trunk (or core) for stabilization and maintaining good posture.
• Hips and legs for lifting and climbing.
• Shoulders for overhead pressing movements.
• Chest for pushing activities.
• Arms for lifting and carrying.

The main types of resistance training are free weights and machines. Both types have advantages that should be considered in determining the resistance training program.

Free Weights

Safety: Risks involved with using free weights include being hit by, tripping over, or being trapped under a weight.

Whole body training: Free-weight exercises are often performed in the standing position with the weight supported by the entire body. This helps promote bone mineralization. Moreover, the movement of a free weight requires muscles to work in stabilization as well as support.

Simulation of real-life activities: The lifting and acceleration of objects represent major parts of sports and other physically demanding activities encountered on a daily basis. The lifting of free weights involves the more natural coordination of several muscle groups.

Machines

Safety: The main safety risk when using machines is getting a finger caught in a chain, cable, or stack of weights.

Design flexibility: Machines can be designed to provide resistance to body movements that are difficult to perform with free weights (such as, hip adduction and abduction, hip flexion).

Ease of use: People who fear they lack the coordination to lift free weights safely feel confident when using machines. It is quicker and easier to select a weight by inserting a pin in a stack than by mounting plates on a bar.

Whether training using free weights or machines, resistance training should be included as a very important part of any exercise program. Adding weights to a workout helps improve strength, endurance, and overall health and provides variety to any training program.

Source: Add Weights to Your Workout; PR 15-05; July 25, 2005; PUBLIC AFFAIRS OFFICE, U.S. ARMY CENTER FOR HEALTH PROMOTION AND PREVENTIVE MEDICINE, ABERDEEN PROVING GROUND, MARYLAND 21010-5403