A: Based on the available scientific information, strength training won't inhibit a child's growth under normal circumstances.

Strength training can, however, cause injury when heavy weights are used or improper exercise technique is employed. When carefully supervised and correctly performed, strength can actually lower a child's risk of sustaining a sports-related injury, since higher levels of muscular fitness serve to protect the musculoskeletal system.

Strength training can, and should, provide a safe and productive exercise for children who show an interest in the activity.

Perhaps the two most critical factors that make strength training a safe, effective, and enjoyable activity for children are quality supervision and adherence to the concept of minimum effective dosage (i.e., the training program should be designed using only the minimum level of resistance needed to produce a training effect).

Q: Does regular participation in aerobic exercise lower an individual's risk of developing cancer?

A: While it has not been shown that a given level of physical activity per se can reduce overall cancer risk, research suggests that exercise often modifies some of the risk factors associated with certain kinds of cancer. Obesity, for example, has been linked to cancer of the breast and the female reproductive system.

In turn, regular exercise has been shown to help promote weight loss. Several studies have also found that men who worked at sedentary jobs for most of their lives had a greater incidence of colon cancer than those in more active jobs. A longitudinal study of Harvard alumni found that highly active or even moderately active individuals had a substantially lower risk of developing both colon and lung cancer than alumni who were less active or sedentary.

On the other hand, exercise will not offset the effects of a high-fat diet or smoking. Still, it can contribute, even indirectly, to a reduced risk of cancer. As such, exercising regularly is recommended by the American Cancer Society as an integral part of its cancer prevention program.

Q: I sweat profusely (literally dripping wet) during my aerobic workout. Is this an indication that I'm out of shape?

A: The reason for profuse sweating is that body core temperature becomes significantly elevated by the increase in metabolic heat production during exercise.

In response to an elevated body core temperature, the brain signals the body to dissipate the excess heat as rapidly as possible. Eccrine sweat glands are then activated, and fluid is transported to the skin so that it can evaporate and create a cooling effect.

Rather than indicating a lack of conditioning, sweat dripping off the body may be more indicative of the fact that the humidity of the environment is so high that sweat can't evaporate. All factors considered, this is not an ideal situation, because it may mean that the body is not being effectively cooled via evaporation.

On the other hand, profuse sweating can also be a sign of being relatively fit, since one of the adaptations to consistent exercise training is that individuals will sweat more and sweat sooner so that their bodies don't store extra heat.

Q: What are the benefits of varying your workout routine?

A: Individuals should consider varying their exercise routines for two fundamental reasons: (1) to prevent boredom associated with doing the same things workout after workout and (2) to avoid or delay reaching a plateau in workout performance and, subsequently, training results. Research has shown that adding variety to an exercise program can improve adherence. Exercise scientists at the University of Florida observed that individuals who modified their workouts every two weeks over an eight-week period appeared to enjoy their workouts more and were more inclined to stick with their exercise programs when compared to individuals who followed the same workout regimens week after week. Varying your exercise routine can also help you stay physically challenged. Many of the body's physiological systems (e.g., the muscular system) adapt to an exercise program within approximately six to eight weeks. If you do not modify your exercise routine, you reach a plateau because your body has adapted to the repetitive training stimulus.

There are several ways you can spice up your current workout routine, including boosting the intensity of your workouts. For instance, if you jog or run, try incorporating some intervals of sprinting (e.g., sprint to a given landmark, then jog to the next one) or adding more hill work to your run. You can also cross train and perform different activities to provide your body with a new challenge. A nice alternative for resistance-training exercises involves changing the sequence in which you perform the training exercises. By fatiguing the muscles in a new order or pattern, you are requiring them to adapt to a new training stimulus. Another option for adding variety to strength-training workouts is to replace some or all of the exercises in your workout routine (e.g., substitute a dumbbell pectoral fly exercise on a stability ball for your typical barbell bench press exercise).

Keep in mind that doing the exact same workout, day after day is not necessarily a bad thing. Some people enjoy a predictable, consistent routine. They don't mind the possibility of experiencing a training plateau and are content to maintain their health and fitness levels with a comfortable exercise habit. However, many individuals need to push themselves to new levels and try different activities to stay enthusiastic and excited about their workouts. By varying their exercise routines, individuals can not only stay physically challenged, but mentally stimulated as well.

Q: Are there any risks associated with excess protein consumption?

A: The human body is unable to store extra protein. Protein consumed in excess of the body's needs is not used to build muscle; rather, it is used for non-protein bodily functions.

If individuals consume protein in excess of their caloric and protein needs, the extra protein will not be stored as protein. Unfortunately such extra protein is converted to and stored as fat. As a result, if individuals consume large amounts of extra protein in addition to their regular dietary intake, any weight gain would very likely be in the form of fat.

Another important point to keep in mind is that the potential for harm exists if protein is consumed in excess. Such harm is most likely to occur in the individual who consumes protein or amino acid supplements.

For example, excess protein may lead to dehydration, because protein metabolism requires extra water for utilization and excretion (i.e., elimination) of its by-products. Since exercising individuals are already at an increased risk for dehydration, the additional strain of protein waste excretion may further promote dehydration.

Excess protein has also been shown to lead to an increase in the loss of urinary calcium. A chronic calcium loss, due to excess protein intake, is of particular concern because it may increase the risk of osteoporosis, especially in women.

Q. What's the secret to looking cut?

A: Physiologically there is no difference between toning and strengthening a muscle.

Many individuals are confused regarding the relationship between muscle strength, muscle tone or definition, and muscle size. As muscle strength improves, muscle tone improves due to a greater density of the muscle fibers.

Everyone has the ability to increase muscle strength and muscle tone to some degree.

Relatively few adults (male or female), however, possess the genetic capability to develop large muscles or the cut physique of the models seen in many of the popular fitness magazines.

To achieve the ''buffed'' look, you must develop reasonably significant levels of muscle mass while simultaneously reducing the amount of fat under the skin.

When this effect is achieved, the well-developed muscles can be seen under the skin. In fact, the majority of individuals have washboard abdominal regions. Unfortunately for most of us, a layer of body fat covers our six packs.

Participating in a balanced exercise program (aerobic conditioning and strength training) and eating sensibly is the best approach to achieving a well-toned, firm body.