This is an excerpt from Heart Rate Training by Roy T. Benson & Declan Connolly.
Wouldn't it be wonderful if you could continue running until you reach the real finish line at the end of life? No premature retirement required. Well, good news! No matter when you start running, whether at 7 or 77 years old, we believe that you can keep going for the rest of your life. The secret is to keep your legs from giving out long before your heart does because, ironically, runners' legs seem to age faster than their hearts.
Think about it: How many former runners have told you they gave it up because of knee problems? Or it was their hips? Or feet, ankles, or maybe their back? In contrast, how many people told you they gave up running because their hearts ached and pained from all the pounding? If you like to run, whether for health, recreation, or competition, we're here to convince you that you can do it for the rest of your life. So, do you run to stay young and good looking? Do you run to socialize and finish smiling? Do you run to push yourself to complete exhaustion in pursuit of peak performances? In short, what is your goal? Whichever one fits your current reason, we believe you can do it for a lifetime, as long as you don't overdo it.
Granted, you probably won't always be as fast as you were at the start of your running life, but you can absolutely keep running until it's toes-up time. We think that our accumulated wisdom, scientific data from heart monitors, and our training methodologies can help you to do this. Of course, we admit that biomechanical breakdown from overuse is not always what forces folks to retire from running. There are accidental orthopedic insults to the legs that not even the smartest training can overcome. Think about ligament or cartilage damage from soccer or football, or accidents such as tripping on a curb. We also admit that a heart damaged by poor lifestyle choices can put a runner on the sidelines. But seldom is the damage caused by well-regulated exercise such as running.
Now is a good time to point out that your maximum heart rate will decline with age. In fact, much of the explanation for declining performance across the lifespan is attributed to a decreasing maximum heart rate. Yes, this is one cause of slowing as you age. But this slowdown is purely age related and is not caused by wear and tear from running. Even that age-related slowdown is thought to happen at a slower pace for active exercisers compared to people who are not active. So, the question is this: How can you keep your legs from giving out before your heart does? We believe there is a simple, scientific solution that will keep you moving: Use those principles of experimentation that we constantly refer to in order to manipulate the givens and variables of your workouts. If you want to avoid the accumulated wear and tear that can force premature retirement, run like a scientist who reads the feedback from his or her heart rate monitor to regulate intensity, control pace, and moderate microdamage to the legs.