Depending on your age, medical issues, and level of conditioning, you must individualize your training plan, whether you intend to participate in the Independence Blue Cross Broad Street Run or a one-mile fun run.

Sudden cardiac death while running is extremely rare. But if you are middle-aged or older, and have cardiac risk factors such as high blood pressure, high cholesterol, or a strong family history of cardiac problems, it might be a good idea to be screened by your doctor before embarking on a rigorous program.

Especially as we age, not exercising regularly results in rapid deconditioning —  you get out of shape really quickly.  This means an increase in heart rate and shortness of breath when starting an exercise program.  Teenage athletes can spend the winter doing little, and get ready for the spring season in just a couple of painful weeks. But with age, the mantra needs to change from "no pain, no gain"  to "slow and steady now wins the race."

The middle-aged athlete who is sedentary for just a few weeks must recondition slowly.  This may mean monitoring your heart rate as you begin exercising and keeping the intensity moderate.  A good guide is to be able to comfortably  have a conversation while you are exercising.

All kinds of running are not the same when it comes to the heart.  Studies such as the Copenhagen Heart Trial suggest that the most favorable regimen is running or jogging at least three days a week, at a pace of a 9- t0 12-minute mile. Possible negative cardiac effects can come with longer duration and intensity, and extreme exercise such as marathon running has been associated with an increased cardiac risk.  For the first 45 to 60 minutes of exercise, there is tremendous benefit, which begins to be lost after an hour. Do not try to cram in a whole week of exercise in one day. To condition properly, you must spread  workouts over the week, rather than going for two or three hours in a single day.

Interval workouts are a hot topic. Many people think they are necessary both for a good workout and to lose weight — which is not true.

But interval workouts can help improve running times.   An interval approach involves bursts of speed for several minutes, followed by a walk or light jog.  For example, if you are used to running a 12-minute mile, an interval workout could be running at a nine-minute speed for a minute or two, then walking for a minute, then running again.

Intensive intervals are not ideal when first starting an exercise program, especially if you are out of shape.  They place an extra strain on the heart and, if there is a blockage in one of the coronary arteries, can increase the risk of a problem.  Instead, start slowly, with frequent workouts (as many as five a week) and for as long as 45 minutes to an hour. If you have chest discomfort or excessive shortness of breath, stop and call your doctor.

After four weeks of this regular aerobic activity, it is safe and effective to add interval workouts.  Interval training can then be really helpful to help break through a barrier if you are stuck at a certain speed and want to take things to the next level.

Training for a run such as Broad Street can be fun, especially if you set goals and follow a program.  The objective is not just to finish the race, but also to feel good about it. You will have a sense of accomplishment, improve your health, feel better, lose weight, and get in shape.  Don't show up the day of the race without preparing. That is not healthy for you or the people you are running with.

Having narrowly averted collisions with poorly prepared runners who suddenly stop to take a walking break — without checking to see whether others are right behind them — I can attest that training helps everyone have the best race-day experience.

David Becker, M.D., is a runner and a board-certified cardiologist with Chestnut Hill Temple Cardiology in Flourtown, Pa. He has been in practice for 25 years.