good artikel : http://www.markallenonline.com/maoArticles.aspx?AID=2"In our sport there are three key areas of fitness that you will be developing. These are speed, strength and endurance. "
Strength is fairly straightforward to do. Two days per week in the gym focusing on an overall body-strengthening program is what will do the trick.
Next are the focused workouts that will give you raw speed. This is perhaps the most well known part to anyone’s training. These are your interval or speed sessions where you focus on a approaching a maximal output or your top speed at some point in each of these key sessions. But again, developing speed in and of itself is a fairly simple process. It just requires putting the pain sensors in neutral and going for it for short periods of time. A total of 15-20 minutes each week in each sport of high intensity work is all it takes.
Now for the tougher part…the endurance. This is where heart rate training becomes king. Endurance is THE most important piece of a triathlete’s fitness. Why is it tough to develop? Simply put, it is challenging because it usually means an athlete will have to slow things down from their normal group training pace to effectively develop their aerobic engine and being guided by what is going on with your heart rate rather than your will to the champion of the daily training sessions with your training partners! It means swimming, cycling and running with the ego checked at the door. But for those patient enough to do just that, once the aerobic engine is built the speedwork will have a profound positive effect their fitness and allow for a longer-lasting improvement in performance than for those who blast away from the first day of training each year.
There is a formula that will determine your Maximum Aerobic Heart Rate, which is the maximum heart rate you can go and still burn fat as the main source of energy in your muscles.
Here is the formula:
1. Take 180
2. Subtract your age
3. Take this number and correct it by the following:
-If you do not workout, subtract another 5 beats.
-If you workout only 1-2 days a week, only subtract 2 or 3 beats.
-If you workout 3-4 times a week keep the number where it is.
-If you workout 5-6 times a week keep the number where it is.
-If you workout 7 or more times a week and have done so for over a year, add 5 beats to the number.
-If you are over about 55 years old or younger than about 25 years old, add another 5 beats to whatever number you now have.
-If you are about 20 years old or younger, add an additional 5 beats to the corrected number you now have.