Exercise Injury Prevention

Running in the Fast Lane | Listening to your Body | Training Errors Training Principles | Practical Training | Psychological Factors

Positive Training Principles - The Strategic View

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.

Crosstraining is another way to put some recovery into a training program. For a regular jogger, replacing a run with a session of swimming, cycling, stairclimbing, or walking would be an example of crosstraining. The values of crosstraining 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.

Source: Halle, J. (Ph.D., Lieutenant Colonel, US Army). Exercise Injury Prevention: Running in the Fast Lane. From "Executive Wellness: A Guide for Senior Leaders." U.S. Army Physical Fitness Research Institute (USAPFRI), U.S. Army War College (Eds.). Carlisle Barracks, Pennsylvania.

Running in the Fast Lane | Listening to your Body | Training Errors Training Principles | Practical Training | Psychological Factors