Your HR Max is calculated by taking 220 and minus your age. For example: 18 years old, 220-18 = 202 bpm; Max HR = 202 bpm.
Use the following training guidelines to prepare for your upcoming Worlds:
• Endurance training is 70-80% of your HR Max
• Cardiovascular “burst” training is 80-100% of your HR Max
When training at the 90-100% heart rate zone, this should be (and can only be) for short periods of time. Think of incorporating this into your cardio work out with intervals of increased intensity. Make sure you accelerate slowly into your interval to be most efficient. In between intervals, decrease your speed, but do not stop.