What result do you want?
billbindo;90220 said:
I re-started my fitness program today. My aim is to grow my energy level, get lean and grow muscle. I decided to have cardio training (run) each day 15 minutes. BUT wouldn't it be better to run 1,5 hour run in one day instead of 15 minute runs daily?
It depends on what you are trying to achieve.
For energy: Every time you perform activity of a demanding nature, your body has an "inflammatory" response. Think of this as an increased metabolism--higher heart rate, muscles warmed up, increased appetite, etc. To a degree, the more often you do this, the higher your energy level will be.
For being leaner: this depends almost 100% on how much you eat compared with how much food energy you expend. It is like comparing how much you deposit vs withdraw at the bank.
For growing muscle: this depends almost 100% on increasing the intensity of your physical activity, and then giving your body the rest it needs to grow in response to that. Other factors like diet are secondary considerations here.
So, to have high energy, do something mildly demanding regularly, such as a short jog, as often as every day, but remember: mildly demanding. To get leaner, eat less. To gain muscle, perform highly demanding physical activity infrequently, and then rest plenty. Note that all physical activity has a "cost" in terms of the repairs your body needs to make to be as good or better than the day before. Your body likewise has a budget as to how much it can afford to recover from.
If you only want to run, then the most benefit you can get from running would be to perform a mild jog or fast walk every day or every other day, and then to perform sprinting exercises for a short amount of time once or twice per week. Ideally you would not be using running as your intense activity, however, as it does not lead to strengthening the entire body proportionately.