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Though it is difficult to precisely define Fitness, total fitness requires adequate muscular strength and endurance, reasonable joint flexibility, an efficient cardiovascular system with a good level of aerobic fitness, and acceptable body composition with control over body weight.


1. Overload - Exercising the body at a level above that which it normally operates. This principle can be accomplished by increasing the frequency of exercise, increasing the intensity of exercise, or increasing the duration of exercise.

2. Specificity: This refers to the metabolic and physiologic changes that occur depending upon the type of overload used. Research studies suggest that a person should perform training exercises in a manner as close as possible to the way he or she wishes to use the improved capacity. Example, fitness for bicycling is best achieved through cycling exercises, etc.

3. Individual Difference - It is critical that the person's relative fitness level at the start of training is considered prior to prescribing an exercise program. Training benefits are maximized when programs are planned to meet individual needs and capabilities.

4. Reversibility - The "if you don't use it you lose it" principle. Once an individual reaches a certain level of conditioning, a regular program of activity must be maintained to prevent deconditioning. Some researchers have estimated that improvements gained are lost in 5-10 weeks, and often times much faster, once the conditioning is stopped.


The overload principle is applied by the use of weights, immovable bars, straps, pulleys, or springs. The muscle will respond to the intensity of overload with the overload created by increasing the load or resistance, the repetitions performed, the speed of muscular contraction, or by various combinations. Three systems are commonly used: Isotonic training, Isometric training and Isokinetic training. Isotonic training, often referred to as weight training, involves the muscle exerting tension in order to overcome a fixed or variable resistance. There are two types of muscular contractions: Eccentric, the muscle lengthens as it contracts, and Concentric, the muscle shortens as it contracts.

Isometric training has no movement during the muscle contraction. One disadvantage to this method is that strength development is specific to the angle at which the force is applied. Another is that there is little if any transfer of isometric strength developed at one joint angle to other body positions, even when the same muscles are involved.

Isokinetic training is working against a resistance that permits movement at a pre-set, pre-fixed speed and enables the muscle to obtain its maximum contraction throughout the full range of movement.

Don't plan on using weight training as your primary source of aerobic training. A one-hour weight training session is usually no longer than about 6-8 minutes of actual muscular work.


The following items must be considered prior to beginning your program:

1. What are your personal objectives? Power training (strength vs. time) is usually six repetitions or less; strength training 7-15 repetitions; strength with muscle endurance 15-25 repetitions; muscle endurance training only 25-50 repetitions.

2. How to get the most use of the available facilities and/or equipment. What is best for you relative to time, convenience and motivation factors.

3. Selection of proper exercises.

4. Proper arrangement of the exercises


The capacity to perform all out exercise of up to 120 seconds in duration depends mainly on this system of energy metabolism. The overload system must be applied in conditioning in order to improve this energy generating capacity. Sports such as football, ice hockey and weightlifting rely mostly on energy derived from the anaerobic system and basically do not require oxygen. Thus a subsequent exercise bout can begin only after an adequate rest period for recovery. Individuals should undertake numerous bouts of intense, short duration exercise and the training activities selected must use the muscles for which the person desires anaerobic power.


Continuous exercise performed for longer than two minutes requires energy from both the anaerobic and aerobic metabolic reactions. If the supply of oxygen is adequate to meet energy needs, then the exercise can be continued in a steady state and the feelings of discomfort from fatigue are minimal. Therefore the intensity at which exercise can be sustained for relatively long periods of time depends upon the body's capacity of support systems for oxygen transport, the heart, lungs and vascular system.

Before engaging in an aerobic exercise program you should consider the following factors:

1. Initial level of cardiovascular capacity.

2. Frequency of training. Three days per week minimum is generally accepted, although some adaptive changes may occur in two days per week.

3. Duration of training - it is known that both continuous as well as intermittent overloads are effective in improving aerobic capacity. Even single 3-5 minute bouts of vigorous exercise performed three times per week will improve the aerobic system. However, performing less exhausting but steady state exercise for 20 minutes or longer will increase the pumping ability of the heart as well as the metabolic capacity of the specific muscles being used.

4. Intensity of training - this is a critical factor. The American College of Sports Medicine recommends that aerobic training, to be most efficient, be conducted 3 days per week utilizing 20-30 minutes of continuous exercise sufficient to expend about 300 kcal. This is usually assured by exercising at a pulse rate of about 70% of maximum heart rate (220 minus your age X 70%).

5. Specificity of Training - it is reasonable to advise that in training the aerobic system for a specific activity such as rowing, swimming, cycling, running, etc., the method of training must overload the appropriate muscles required by the activity as well as provide stress for the heart and vascular system.

6. Muscle Fiber Type - the average percentage of slow-twitch fibers in sedentary men is about 45-50 percent, but the variation is large. It would seem logical that these people, with a large proportion of slow twitch fibers in their leg muscles, would be successful in endurance running, while those with a distribution favoring fast twitch fibers would excel in sprint activities (more on testing for these factors later). It appears that the distribution of these fibers is determined by genetic code largely fixed at birth.


Start slowly, warm-up before you start any exercise program, dress sensibly, and allow a cool-down period of 5-10 minutes.

References: Nutrition, Weight Control and Exercise by Frank Katch and William McArdle and Sports Physiology by Edward l. Fox.

Author/speaker and an expert in ”Sports Performance Enhancement”. Jack Medina is available for speaking engagements, consultation and personal training of athletes in various sports, professional and amateur. Jack has written a new book, “The Winning Edge: Fueling & Training The Body For Peak Performance” with Dr. Roy Vartabedian, an internationally known New York Times Best Selling Author of the “Nutripoints” program for optimal nutrition. Both books are available online at Jack also has a monthly ezine (newsletter) available free which can be subscribed to on his website. All subscriber’s addresses will be confidential and not sold or given to any other organization or group.

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