Here are many reasons why heart rate zone training is important. Perhaps the most important reason is the prevention of overtraining, that is, excessive frequency, volume or intensity of training leading to fatigue, but also injury (Clark, 2013). Although this is also due to lack of sufficient rest and recovery between workouts, training too hard is the leading cause of injury. It is important for beginners to maintain cardiovascular training in zone 1 for at least 30 minutes three times per week for several weeks before progressing to higher zones. This is to build the endurance of their cardiovascular muscles, especially the heart, so that their heart rate and blood pressure drop quickly after reducing the training intensity. If their blood pressure and heart rate take a long time to drop even after a reduction in intensity, this means that the cardiovascular muscles will not be able to handle the intensities required by the higher training zones. Another reason to train with heart rate zones is to maximize fat. loss. Just because someone is burning calories doesn't mean they are burning fat calories. The body uses carbohydrates, fats, and proteins to produce energy for exercise, but carbohydrates are primarily used. At low intensities, a person is not "huffing and puffing", so they are taking in enough oxygen for their muscles to function. The aerobic energy system is used exclusively. Aerobic exercise tends to burn sugar first and activate pathways that break down muscle. Zone 3 training initiates the anaerobic system. Anaerobic interval training is so effective because it forces the body to burn fat to maintain the intensity level...... middle of paper ...... and be sure to monitor the client's progress , in order to adjust it timely. training (i.e., moving them to Stage II or III, or increasing zone intensities) so that the client continues to be motivated and challenged. A related challenge is that even with a willing client attempting to adhere to the training zones, the client may still have difficulty remaining alone within the prescribed zone. Proper equipment is the solution for this, and the trainer must therefore ensure that the client understands the need to have a reliable method of heart rate monitoring. This is easy if a treadmill or similar bike is used, as most have built-in monitors. If these are not used, the customer may need to invest in a heart rate monitor. This will be particularly important in stages II and III where the client must return to zone 1 after intervals in zone 2 and/or 3.