Q: I am severely obese—I am 5 feet 4 inches and weigh 300 pounds. I stand all day at work and by 5 p.m. my knees are screaming. I would like to start exercising, but I don't want to damage my knees. What should I do and how do I begin?
A: It's not easy to decide to start exercising when you are in pain and feel physically limited. But it's great that you've decided to do so, since you can improve many aspects of your health by becoming more physically active.
It's likely that your extra weight is putting more pressure on your knees, and with an all-day, on-your-feet job, you could be standing in such a way that your knees are out of alignment (either hyperextended—locked out straight—or rotated), which can add more stress to the joints. Often, doctors recommend weight loss as a way to reduce knee pain. While this is a good idea, sometimes overweight and obese people feel that they should only start exercising after they have first lost some weight. Others think exercise isn't as important as dieting, so they skip the workouts.
But exercise plays a major role in healthy weight loss—and, most importantly, in improving health, strength and stamina regardless of whether weight is lost. A 2009 study in the Archives of Internal Medicine profiled 430 obese, sedentary women who exercised for three to four days a week for six months. Some of the women were doing very minimal, very-low intensity exercise (around 18 to 25 minutes of easy walking per session). Even so, not only did the women lose an average of 6 to 8 pounds from the exercise alone, but even these small amounts of exercise improved their heart health and quality of life. And the more exercise the women were able to do, the more improvement they saw in areas of mental and physical functioning.
Because you are very overweight and already experiencing pain, you're right to proceed cautiously. Your first step should be to get the okay from your physician. Ask if you qualify for a prescription to a physical therapist or exercise physiologist rehab program for obesity-related conditions. If so, you can get expert guidance to start an exercise program and possibly have some or all of it paid for by insurance if you have it.
You may feel out of breath quite easily, not only from being out of shape, but from the increased oxygen demands from being very overweight. Also, you may need to monitor your blood pressure and glucose levels. Your physician can help you determine any special needs you may have.
Once you have the go-ahead, if you are not consulting with a health-care professional, then you need to figure out what you can do and what you like to do. Even though there may be some activities that you don't feel comfortable doing, you have plenty of options.
Since you have knee pain when standing, you may want to start very conservatively with a workout that's low-impact, or even done while seated. Here are some ideas:
At first, any class is a good idea, so you should try a variety of cardio and weights workouts. Workouts that incorporate weights, especially at a beginner level, will help you to become stronger and develop more muscle endurance, but may not provide a sufficient cardiovascular boost, so make sure you include more aerobic activities such as water exercise, walking, cardio machines, dancing or cardio classes.
Monitoring your effort level
If you haven't been exercising, it is very easy to work harder than you should. Instinctively judging your individual effort by using what is known as rate of perceived exertion is a common way to gauge intensity during exercise. To work at a moderate level it's suggested that the exercise feel like it's "somewhat hard." Higher intensities and more vigorous workouts will feel hard or even very hard. As a novice person, it's a good idea to avoid working out hard or very hard when you first start out.
To stay on the safe side, rather than gauge how you feel with the perceived-exertion approach, use your heart rate to gauge your intensity. First you need to figure out what your "target" heart rate should be during a workout. There are several ways to estimate this, but a 2008 study in the journal Medicine & Science in Sports & Exercise evaluated ways to determine exercise intensity in obese people. They found that using a formula that takes resting heart rate into account is the preferred approach for overweight to severely obese individuals.
Here is the recommended formula to determine your target heart rate:
Step 1. Estimate your maximum heart rate, or HRmax. This is your age subtracted from 220. For example, if you are 40, your HRmax is 180.
Step 2. Determine your resting heart rate: When you wake up in the morning, while still in bed, measure your resting heart rate by placing two fingers on the inside of your wrist, or just off-center from the front of your neck. (Don't use your thumb, as it has its own pulse.) Pause until you feel a pulse. Then, start counting at zero for 30 seconds. Multiply the number by two, and that's your resting heart rate.
Step 3. Choose the target range of your desired exercise intensity, or how hard you want to work. Research shows that cardiovascular improvements come from exercising at 50 percent or more of your maximum heart rate. Since you aren't fit yet, stick to this low end of the range. After a period of three to six months or longer, once you are fit and in shape, you may want to push yourself to exercise at higher levels.
Use the 50- to 60-percent intensity range to determine your target heart rate. This is the heart rate that you want to stay at, or below, during your workouts. If you go above this number, you may be pushing yourself too hard.
Step 4. Plug the numbers into the following formula:
Target Heart Rate = [Intensity x (HRmax - resting HR)] + resting HR
Here is an example:
Step 1. A 46-year-old person has a HRmax of 174 beats per minute. (Theoretically, this is the maximum number of beats per minute that the heart will beat; this is just an estimate and varies with individuals, however.)
Step 2. Let's say her resting heart rate is 80.
Step 3. We're aiming for a target intensity of 55 percent, or 0.55.
Step 4. So we plug the numbers into the formula:
This person should then work out at a level where she stays at 132 beats per minute or fewer.
Once you've gotten your doctor's approval and you've figured out which activities to try, you can start adding exercise according to your level. During each cardio workout, slow down, but do not stop, and periodically assess your heart rate. If you find it difficult, purchase a heart rate monitor. Some cardio machines also have heart-rate monitors built in.
Once you start, play close attention to how you feel. If something hurts, modify or stop what you are doing. Don't think that just because you are out of shape means you need to work through any pain or severe discomfort. If your knees or other joints bother you, you may need to try another type of exercise. In the days after your workouts, if your muscles feel sore or your joints hurt, you may need to work a little easier next time, or change to a different type of workout.
After you have become used to your workouts, you will get fitter and you will find that you can do harder workouts without feeling as if they're as difficult. You can increase the intensity, or your heart rate, as you get fitter, too. Eating more healthfully will help provide the energy to exercise and can definitely help you to lose weight. But even without weight loss, exercise can make you stronger and healthier. Good luck!
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