Now that we have been through the energy systems it gives us an insight into what type of activity uses which energy system, and also how long the different energy systems last for, the fuel they use and any waste product that they produce. This is extremely useful if we want to train someone for a particular type of sport, want to make someone lose weight, or just make a personal training client fitter and slimmer.
We can, for instance, see that the only energy system that uses fat as a fuel is the O2 system, which is dominant from 0-60% of maximum exertion. Therefore this is the energy system that we use the most when at work, sitting watching telly, shopping and so on.Therefore if we can increase the amount of energy we use at rest it will have an important bearing on fat loss. Metabolic rate at rest happens to increase lots the more lean muscle thet you have, so by resistance training we will increase lean muscle, so we will increase metabolic rate at rest, so we begin to target the O2 system more for most of the day every day, and will burn more fat!
Similarly, if I have a personal trainer client in Windsor who is a member of a rowing club, I can improve his rowing by targeting the energy systems used in rowing. A 2000m row uses the aerobic and anaerobic systems in about a 60-40 split, so our training should be a combination of longer endurance work (O2 system) coupled with anaerobic intervals of higher intensity (60-90%) for 1-3 minutes. If I have a personal trainer client in Maidenhead who wants to be better at sprinting as she wants to win the parents race at the school sportsday, then we need to work mainly on the CP system, so shorter maximal bursts, as this is the energy system almost exclusively used in the 100m sprint. On the other side of the scale I recently trained Wendy in Egham for the Benidorm Marathon, as this is a distance race the energy system dominant in the O2 system, so the training is mainly focused on longer endurance types of training.
For a broader overview have a look at the energy continuum diagram, where various sports are ranked by their aerobic and anaerobic demands..