by Jack B. Fu, MD
My doctor told me I should exercise regularly. What does that mean? How long and how often should I work out? What types of exercise should I do?
As a cancer physiatrist, part of my job is to guide cancer survivors through starting an exercise program. Like most cancer exercise specialists, I follow the cancer survivor exercise guidelines published by the American College of Sports Medicine Roundtable in 2010. The ACSM divides exercise into three categories.
1. Strengthening Exercise
Cancer survivors should try to do strengthening exercises two to three times per week on nonconsecutive days. When you start, use light weights of one to five pounds, resistance bands, or no weight at all. Perform exercise sets of five to ten repetitions. Increase the weight incrementally until you feel your muscle is worked after a set. As time passes, you will slowly notice that a weight or resistance level that once made you feel worked after a set no longer does so. This means you are getting stronger. At this point, you may slowly and incrementally increase either your repetitions, or the weight or resistance. However, don’t increase weight or resistance while sacrificing good form. Also, be sure to balance your strength training by working out different muscle groups.
2. Flexibility Exercise
Survivors should aim for three to four nonconsecutive days per week of flexibility exercise on the days you are not strength training. Be sure to perform these exercises after your muscles have warmed up. Stretch muscle groups slowly and steadily, and avoid bouncing. You should also never stretch to the point of feeling pain; however, some mild discomfort is acceptable.
3. Aerobic Exercise
The ACSM guidelines recommend at least 150 minutes per week of moderate-intensity aerobic exercise, or 75 minutes per week of vigorous-intensity aerobic exercise. Where this can get confusing is what may be “high intensity” for one person may be “low or moderate intensity” for someone else. For example, brisk walking could be moderate intensity for some people, but vigorous intensity for others.
The ACSM guidelines recommend at least 150 minutes per week of moderate-intensity aerobic exercise, or 75 minutes per week of vigorous-intensity aerobic exercise.
So how do you figure out what’s considered “vigorous intensity” or “moderate intensity” for you? There are several ways to determine the intensity of an aerobic exercise. The two methods I find the most practical and easy to implement are the talk/sing test and the percentage of maximum heart rate calculation.
• Talk/Sing Test: To determine the intensity of an aerobic exercise, try to see how much you can talk and whether you can sing while doing the exercise. If you can sing without straining, then the exercise is low intensity. If you can talk but can’t sing, then it’s moderate intensity. And if you’re only able to say a few words without struggling, then you are performing a high-intensity, or vigorous, aerobic exercise.
• Percentage of Maximum Heart Rate: Due to the proliferation of wearable fitness trackers, like Fitbit, using your heart rate to determine exercise intensity has become much easier. Ten years ago, you would have to interrupt your exercise, put your fingers on your wrist and count the pulses of your radial artery for a full minute. But now with wearable fitness trackers, you can easily check your heart rate throughout your exercise. Some devices are even able to show your exercise intensity (by calculating it using your age). However, if your wearable activity device does not display exercise intensity, you can do some quick math to figure out your exercise intensity ranges as they relate to the percentage of your maximum heart rate. Afterward, you can just jot down these ranges, or remember them, so you’ll have them on hand whenever you exercise.
A Word of Caution
Before beginning any regular exercise program, speak with your physician. Your doctor may identify specific medical concerns or precautions (like your fall risk, musculoskeletal issues, laboratory values, or a compromised immune system) that you should take into consideration when implementing an exercise program.
Here is how to calculate exercise intensity using your heart rate:
- First, calculate your maximum heart rate. That is 220 – your age. So, if you are 60 years old, your maximum heart rate is 220 – 60, or 160 beats per minute.
- Next, calculate your aerobic exercise intensity zones:
- Low Intensity Aerobic Exercise is 40-50% of your maximum heart rate. In our example, this would be 64-80 beats per minute.
- Moderate Intensity Aerobic Exercise is 50-70% of your maximum heart rate. In our example, this would be 80-112 beats per minute.
- High Intensity Aerobic Exercise is 71-85% of your maximum heart rate. In our example, this would be 113-136 beats per minute.
For many cancer survivors, the barriers to exercise can be difficult to overcome. As such, many cancer survivors report declines in their physical activity after cancer diagnosis. Research has shown that cancer survivors want to talk about physical activity with their physicians; however, doctors often neglect to address the topic. Furthermore, the symptoms and side effects associated with cancer and its treatment can discourage physical activity.
However, exercise has not only been shown to increase cancer survivors’ well-being, but it has also proven to be one of the most useful treatments for cancer-related side effects, including fatigue. It also may improve cancer survival and reduce your risk of cancer recurrence. Knowing these facts, you owe it to yourself to exercise. At first, it may be difficult to exercise regularly but, over time as the habit forms, it will become much easier. So, don’t let these obstacles stand in your way. Make the effort to incorporate physical activity into your routine. You will feel better, and you may even live longer.
Dr. Jack Fu is a physiatrist and an associate professor in the Department of Palliative, Rehabilitation & Integrative Medicine at the University of Texas MD Anderson Cancer Center in Houston, TX. You can follow Dr. Fu on Twitter @JackFuMD.
This article was published in Coping® with Cancer magazine, January/February 2018.