How much exercise is enough?  The minimum that will produce a result should always be used.
Any excess of the minimum will be wasted effort at best and counter-productive in the worst-case scenario.
  For any budding athlete to much exercise could be worse than no exercise at all.
  From a natural inclination to equate more with better, many coaches will train their athlete far too much that they are literally preventing good results.
It's just impossible to train hard and train a large amount at the very same time.
  Coaches just have no choice in the matter.
  They can only have one or the other, they just cannot have both.
  If they insist on both this will only cause burnout to the athlete and they'll be forced to reduce the intensity of training.
  In some cases a large amount of training is required it just depends upon the sport and the circumstances.
  As an example a long-distance runner must train in running much more than a sprinter.
  No amount of 50 yard sprints will train men properly for a 20 mile run.
  On the other hand too much practice of 20 mile runs will prevent a sprinter from improving his performance.
  In both cases there is a limit to the amount of training that the athlete can do while improving or maintaining a certain level of performance.
  If the distance runner runs too much his times will get worse and the same thing will happen to the sprinter.
  The sprinter must train with very high intensity whilst the distance runner must not train in such fashion.
  If he attempts to run at a maximum level of intensity it's extremely unlikely that would last a full mile much less 20.
  In summary the amount of training and intensity of training must be directly related to that particular sport and must be balanced in relation to each other.
  If the intensity is increased and the amount of training must be reduced.
  A coach just has no choice in the matter.