The importance of exercising the whole body is really huge. We have to exercise the front and the back side of it proportionally. When we workout the front of the thigh we should workout the back side as well in order to balance the result. The schedule in the gym should include a variety of exercises to practice all the parts of the body.
Without muscle balance, problems such as humps (strong chest - weak back), spine problems (dorsal strong - weak abs) may appear. This can happen as a result of a bad workout but also because of the fact that we don't workout at all. Our modern sedentary lifestyle leads to such imbalances. If we finally decide to include some action in our lives we must do it right...
The workout should be stable, progressive and specific (it should be continuous, change progressively and be in accordance with our needs). Frequency (how many times a week), intensity (how much burden on the body), duration (how long) are required if we want to see the results. The body has to work over its normal levels and with gradual increase in frequency, intensity and duration. This does not mean we have to "burn" in training because the body responds to small changes but it needs time for the adaptation and then it waits for the next change to improve again.
Every different aspect of fitness (aerobic, strength, flexibility), requires special training, for example to strengthen your feet you need special exercises with weights, to improve your cardiovascular capacity you need aerobic workout in the aerobic room, the treadmill or a training bike.
There are different ways to workout to gain the benefits of exercise. If, for example you work out at a constant level of intensity and for a predetermined period of time, accordingly to the international standards, it is very good for improving your aerobic capacity.
Frequency of training
For improvement: 4 to 5 times per week of aerobic workout (start with 3 times and add workouts only after you've reached the desired level of fitness) and at least 3 workouts with weights can bring the desired results.
For maintaining: at least 3 workouts a week. The results of training are lost if we stop exercising for 2-2,5 weeks, depending of course on the fitness level of each one.
Over training can lead to fatigue, anemia, immediate or chronic injury and in the case of weights reduction in performance, strains and pains.