• The F.I.T.T. Principle
  
  The F.I.T.T. principle is a basic philosophy of what is necessary to gain a training effect from an exercise program. F.I.T.T. stands for Frequency, Intensity, Type and Time. The principles behind it can appplied to both Cardio-respiratory Training and Resistance Training. They are based on the 'Principles of Training' namely:
  
  Specificity
  Overload
  Recovery
  Adaptation
  Reversibility
  
  To be successful, someone who trains, must integrate several factors into their training programme. This is where the F.I.T.T principle is useful. For those of us who are continually looking to gain muscle, we know that we need to change our training programmes at intervals as the body as a habit of quickly adapting to overloads put on it. This is one of the reasons why we plateau. So we have to come up with many different  ways to train in order to keep improving.
  
  Frequency
• 
  The frequency of training each body part varies with the amount of work done at each exercise session.  If you want to do more work at each session then you would exercise less frequently as you will need more time to recuperate. If you do less work per body part at each session then you can train more frequently.  A factor in how often you will train depends on your ability to recuperate after your workout and be ready for the next workout.  This will be something you will determine on a personal basis.  It is better to be consistent in your workouts and make steady progress than to overtrain and be discouraged from inconsistent and poor training results.

A general guideline would be to do each body part 1 to 2 times per week or every 4-5 days if you are a beginner or are doing high load workouts. For lower intensity workouts or higher trained individuals you could try doing each body part 2 to 3 times per week. You can do different areas of the body on different days or you can train your whole body at each workout only doing a few exercises for each body part.

Intensity

Intensity is related to how hard we are training. It represents the degree of effort we put into our training and is probably the mosy important factor in improving our performances. Unfortunately for those who fail to meet their goals, it is often the one factor most people ignore

One of the measures that we can use when we are training is heart rate, not by the faces we pull when we lift the weights!
Using your  Target Heart Rate Zone, (which is determined by your fitness level and your age) low fitness individuals will attain results training at 50% to 70% of their maximum heart rate as their Target Heart Rate Zone. Higher fitness individuals will train at 70% to 85% of their maximum heart rate as their Target Heart Rate Zone.

A simple way to determine your maximum heart rate is to use the following formula:
220 - age = Maximum Heart Rate

Maximum Heart Rate
An example for a 40 year old person would be as follows:
220 - 40 = 180 beats per minute (Maximum Heart Rate)

A Low Fitness Person would train at 50% to 70% of 180 beats per minute which is 90 to 126. They should keep their heart rate between 90 and 126 beats per minute for the required time of the exercise. A Higher Fitness Person would train at 70% to 90% of 180 beats per minute which is 126 to 162. They should keep their heart rate between 126 to 162 beats per minute for the required time of the exercise.
   
Knowing your heart rate is important for three reasons:

1.  It assures you are training at the right intensity to gain benefit from the exercise.
2.  It also assures you are exercising at a safe intensity.
3.  It can tell you the amount of time you exercised in your target heart rate zone.

Intensity is more complicated to measure in resistance training than in Cardio respiratory training. The main aspect of intensity is workload.  The amount of work you do during a workout is your workload.  Your workload can be measured by three components. One component is the amount of weight you lift during an exercise. Another component is the amount of repetitions and sets you performed of that exercise.  A repetition is one complete movement of an exercise and a set is the number of repetitions an exercise is performed before stopping.  The third component is the length of time it took you to complete the training session. 

Therefore we can summarize by saying the workload or intensity of the training session can be measured by how much weight was lifted, the number of repetitions that was completed, the number of sets of the exercises that were performed and the amount of time it took to complete the workout. You can also determine your workload for just one exercise as well as an entire workout.  So it is plain to see that any combination of lower weights, less sets and repetitions and more time will decrease your intensity and by increasing weight, sets, repetitions and less workout time will increase intensity.

Novice lifters should choose a weight that can be performed 8-12 times (repetitions)  before momentary muscle exhaustion prevents you from doing another repetition.  This is called training to failure and is important because as you are doing your repetitions your muscle will start to fatigue and the last few repetitions will be at maximum effort or close to maximum contractions. These last few repetitions are what will create a training effect and make changes in the muscle in the shortest period of time.

When you get to a point where you perform more than 12 repetitions then you add weight the next time you do the exercise.  If you do less than 8 repetitions on your exercise then you do less weight next time and work your way back up to 12 repetitions before you add more weight.  It's that simple!

If you are training your whole body in one exercise session then choose 1-2 exercises for each muscle group and perform 1-3 sets of each exercise.  When you do a split-routine or do different muscle groups on different days then you can perform 2-4 exercises per muscle group and 2-4 sets of each exercise. Please be cautious of doing too many sets and exercises.  If you train your sets to muscular failure there is no reason to do numerous sets to get results. You will see other people in the gym doing many sets at a sub-maximum intensity; this is inefficient and ineffective training.  They need to do many sets to get the same training effect you will get with less sets at the proper training intensity! 
 
Time

It is necessary to maintain your proper intensity (target heart rate zone) for a duration that will create a training benefit. Low Fitness individuals should maintain their heart rates in their target zone for a minimum of 12 to 15 minutes.  This does not include warm-up or cool down periods. As your fitness level increases the exercise time in your target heart rate zone can be extended to 20 - 60 minutes of continuous aerobic activity. Unless you are a competitive athlete, training beyond 60 minutes in your target heart rate zone provides little additional training benefits for the amount of effort exerted. If you are overweight however, long training sessions at a low intensity (50% to 60% of maximum heart rate) utilize fat as an energy source and are helpful in a weight/fat reduction program. 
 
As a component of intensity and workload, time is important. As a beginner or intermediate trainer, muscular endurance may not be well developed.  Therefore training too fast at the onset won't allow you to handle reasonable weights, and training too slow will not give you an efficient and high intensity workout. I recommend initially training at no more than 2-3 minutes in between sets of exercises.  As you become more trained you can try to get to 1 minute between sets and even 30 seconds on some of the assistance or lighter exercises.  Obviously the size of the muscle group being worked will determine how taxing the exercise is on the body. Larger muscle groups such as the quads and back will need longer to recover between sets than say the biceps.
 
Type

There are two types of exercises for muscle groups, main and assistance (minor). Basically, your main exercises involve the most muscle mass.  They usually involve more than one muscle group when exercising and you can use the greatest weight resistance with these exercises.  The assistance exercises isolate the muscle group by concentrating on the simple movement of that muscle group and eliminating or minimizing the involvement of other muscle groups. Have variety in your choice of exercises.  Don't do the same exercises the same way every time you train.  Variety will shock the body and won't allow it to get used to the same exercises.

If you are trying to change your body composition by gaining more lean muscle mass, then concentrate on the main exercises for muscle groups and do fewer assistance exercises.  This will stimulate the most muscle mass and create the greatest change in body composition in the shortest time. Utilizing the main exercises will also help to develop the body proportionally. Many individuals spend too much time and effort concentrating on specific muscle groups and will achieve less overall results then when using the same effort with more comprehensive exercises.