The test we do at the Health Center is a measure of your cardiac fitness based on the length of time it takes you to get to a calculated heart rate based on your age. The intensity and workload is the same for everyone that steps on the treadmill. The only thing that changes is the target heart rate that you are trying to get reach. The longer it takes you to get to that heart rate, the more fit your heart is.
The type of exercise you do dramatically affects the test results. If you do only anaerobic training (very high heart rate) you essentially are training your heart to respond to workloads and/or exercise with a high heart rate. So even when you are doing something that you perceive is not very hard (light jogging, fast walking, our treadmill test) your heart will responding the way it has been trained, with a high heart rate.
If you exercise to build an aerobic base (70%-80% of your maximum heart rate) you are training your heart to respond to workloads and/or exercise with a gradual heart rate increase, which is obviously healthier. When you do have to work hard like in a fire or during a rescue, your heart will still get anaerobic; just not as quickly and not as high a heart rate. Again, this is healthier.
On the flipside, anything less than 60 percent of the maximum heart rate usually benefits beginners and/or those recovering from an injury.
Lastly, there is a time and a place for anaerobic training. Doing the mountain, stadiums, skills course...are very good exercises to teach your heart to work in an anaerobic capacity. But you should first build an aerobic base, then work in the anaerobic. As the “Worlds Fittest Man” and six time Triathlete of the Year writes; “the improvement you can get in performance from developing your aerobic fat burning system is huge compared to the improvement in performance you can get from doing the high-end anaerobic carbohydrate burning workouts. And our bodies cannot develop both systems very well at the same time. Which means that to build a base properly, an athlete has to have the patience to work the aerobic system exclusively for a huge block of time.” This base building could be as short as a three-month period.