For a great workout, we do less miles but allow the run to challenge our heart rate and build a deeper endurance. But why? Team Oregon uses hills to exert the body, but cautions against changing heart rate strain...
"Maintaining even effort with a Heart Rate Monitor"The best way to see the amount of effort you are using, is by training and racing with a heart rate monitor. It acts like the speedometer in your car to let you get instant feedback on your effort. When using the heart rate monitor in training let your heart rate rise 5 - 10 beats over easy training rate on the uphill and try to stay 0 – 5 beats under easy rate on the downhill. When racing, allow only 5 beats over racing heart rate on the uphill.
Now, lets run.