For more than forty years, fitness instructors have based exercise prescriptions on the maximum heart rate formula of 220 minus your age. A study from Oakland University in Rochester, Michigan shows that this formula may be wrong (Medicine and Science in Sports and Exercise , May 2007). The researchers found that the original formula overestimated the maximum heart rate for younger exercisers and underestimated the maximum rate for older ones. The new formula they recommend is 206.9 - (age x .67) = maximum heart rate.
Athletes train by taking a hard workout on one day, feeling sore on the next day, and then going easy for as many days as it takes for the soreness to go away. Then they take another hard workout and repeat the cycle. Most exercise physiologists and coaches tell their conditioned athletes to raise their heart rates to 80 to 100 percent of their maximum when they take a hard workout. For people who exercise for fitness, a hard workout usually means exercising at 60 to 80 percent of maximum heart rate.
However, the maximum heart rate formulas are set by averages of large populations. Your own maximum heart rate is determined by your fitness level as well as your age. Your legs drive your heart, not the other way around. When you start to exercise, your leg muscles contract and squeeze blood from your veins near them. Then when your leg muscles relax, your veins open and fill with blood. This alternate contacting and relaxing of muscles pushes extra blood toward your heart. The increased return of blood to your heart speeds up your heart. People with stronger muscles pump more blood towards their hearts and therefore can get a faster heart rate.
Since there is huge variation between individuals ranging from competitive athletes to novice exercisers, you would be better off setting your workout level by "perceived exertion", rather than by any formula based on averages. "Perceived exertion" means that your brain interprets how hard your are exercising, and you can respond to these signals. As you exercise more intensely, you become short of breath and your muscles start to burn and hurt. You can interpret your own effort and discomfort levels to decide how hard you should work on a hard day or an easy day.
People who are just starting an exercise program or who do not exercise regularly should use much lower levels of effort. They should never try to get to their maximum heart rates because they are the ones most likely to suffer heart attacks during exercise. Start any new exercise program slowly and build up your level of fitness gradually. More