MUSCULAR ENDURANCE & BALANCE

There is no doubt that, in varying degrees, strength underlies all motor performance. In an isolated sense, STRENGTH may be thought of as the capacity of a muscle or group of muscles to exert maximum pressure, or force, against a given resistance in a limited period of time. This muscular force, however, can be exerted under various conditions. A muscular force exerted against an immovable object, with no or very little change in the length of the exercised muscle, is called static or isometric. A muscular force exerted against a movable object, with a change in the length of the exercised muscle, is called dynamic or isotonic. Attempting to push down a wall is an example of static force; lifting a barbell is a dynamic force. Also, the nature of the intensity (given resistance) can be changed so the athlete has less resistance, over a longer period of time. This mode of resistance training is referred to as MUSCULAR ENDURANCE. Muscular endurance can be defined as the ability of a muscle to continue to contract over a period of time that requires many repetitions with a somewhat lighter resistance.

Strength is relatively easy to increase, if one follows some fundamental guidelines. To build strength, one uses relatively few repetitions (5 to 10 to 12, depending on age) and maximal resistance. Moving through the range of motion against resistance (isotonic) is thought to be more effective than static muscle actions against resistance (isometric) because strength builds "specifically" (specificity of training). When one performs a strength exercise in a single position, strength increases, but almost exclusively for that position and not for other positions. For this reason most of the strength exercises in the basic program require movement through the full range of motion to ensure the buildup of strength at all joint angles. In addition, most of the strength exercises in the basic program involve slow movement through the full range of motion. Moving slowly allows for the identification of particularly weak areas in the chosen range of motion, and focusing on them during the exercise allows the athlete to equalize strength throughout a full range of motion. In doing so, the athlete helps the muscle to maintain a complete stretch, flexibility, and to some degree balance, or proportion. All of which are important to any resistance program.

Muscular balance is the strength, power, or endurance of one muscle, or muscle group, relative to another muscle group. Muscular balance is usually expressed in terms of relative strength: Joint agonists and antagonists (e.g., biceps curl vs. triceps press) are most often compared, although contralateral (e.g., right vs. left) comparisons and comparisons of upper and lower body muscles (bench press vs. squat) are also made. A well-designed program includes exercises for all the major muscle groups. Keep in mind muscle balance between joint agonists and antagonists when choosing exercises to insure against activities that may cause a strength increase in one muscle group without a concomitant increase in its antagonist. Examples are the internal rotators of the shoulder in throwers and the quadriceps in speed skaters. As the prime mover of a movement becomes stronger, the antagonist is placed under increased stress as a joint stabilizer. Therefore, and theoretically, the antagonist should then be trained to aid in both performance enhancement and injury prevention. Not surprisingly, this may be why many strength and conditioning professionals feel that an athlete’s performance will be diminished if all the muscles of the athlete are not developed proportionally. Hence, it is helpful to know the strengths and weaknesses of joints and muscle groups of each individual athlete when assigning the frequency and volume of exercises.

Remember, an athlete needs to spend time on all major muscle groups to insure overall development. Weak areas need to be stressed and given priority, whereas strong areas may just require maintenance. This brings us to how muscle balance ratios are measured, or can be determined with accuracy; which can be difficult. However, finding an excellent resource such as the "Essentials of Strength Training and Conditioning" from the National Strength and Conditioning can ease some of the variables in developing any quality program.

Emphasizing a full range of motion and muscle balance is of special importance to all athletes who train for strength. Especially, those that are in the beginning stages of resistance training such as our adolescent or youth aged athlete. Additionally, strength conditioning is also specific to the velocity of the muscle action being trained. Therefore, it is recommended (and those athletes that are under the supervision of a coach/adult, consult with them) that once a certain level of strength has been attained through the full range of motion by slow contractions; faster contractions should then be added (plyometrics) to supplement a well thought out resistance training program.