Exercise During Cancer Treatment

Exercise during cancer treatment is not just permitted. It is recommended, and the recommendation comes with figures.

The American Cancer Society publishes a Nutrition and Physical Activity Guideline for Cancer Survivors. It sets a weekly target: build up to at least 150 to 300 minutes of moderate-intensity activity. Or 75 to 150 minutes of vigorous activity. Or a mix of the two. It also calls for muscle-strengthening exercise on at least 2 days a week.

Moderate intensity has a plain definition: about as much effort as a brisk walk.

A more technical measure exists too. Intensity is described in METs, short for metabolic equivalents of task. One MET is the energy you use sitting still. Light activity is under 3 METs. Moderate is 3 to 6. Vigorous is 6 or more.

Those are targets to build toward, not a starting line. Starting slowly and increasing over time is part of the guideline itself.

In 2018 the American College of Sports Medicine convened an international roundtable. It reviewed the evidence. NCI reports its conclusions. The useful part is that they are graded, not uniform.

Strong evidence:

• Aerobic training at moderate intensity, resistance exercise, or both, during and after treatment, reduces anxiety, low mood, and fatigue. It also improves quality of life and physical function.
• Exercise training is safe in people who have, or might develop, breast cancer-related lymphedema.

Some evidence: benefits for bone health and sleep quality.

Insufficient evidence: that activity prevents heart damage from treatment. Or that it prevents chemotherapy-induced nerve damage in the hands and feet. Or that it improves thinking, falls, nausea, pain, sexual function, or how well treatment is tolerated.

That last list matters. If someone tells you exercise will protect your nerves during chemotherapy, the evidence does not currently support it.

The roundtable reached one overall conclusion. Exercise training and testing are generally safe for cancer survivors. And every survivor should keep up some level of physical activity.

Fatigue is where the evidence is strongest. NCI's fatigue summary for health professionals puts numbers on it.

The National Comprehensive Cancer Network rates physical activity as category 1 for cancer-related fatigue, during and after treatment. Category 1 is its top tier of evidence. Randomized trials have cut fatigue by about 35%. Vitality rose by about 30%.

A Cochrane review of 56 studies, covering 4,068 people, found that aerobic exercise significantly reduced fatigue during or after treatment. A 2018 review of 245 studies compared approaches. Aerobic exercise and resistance exercise each beat usual care. Doing both gave the largest effect.

Strength training holds up on its own. One trial gave 160 people with stage 0 to III breast cancer twelve weeks of strength training, twice a week. It beat a relaxation program on reported fatigue, and attendance reached 97%.

The same NCI summary names a goal of 3 to 5 hours of moderate activity a week. It also says building up takes time. Start lighter and shorter. Studies have shown this can be done safely both during and after treatment.

One study followed 1,033 people who had chemotherapy in the past two weeks. It sorted them three ways: no exercise, under 150 minutes a week, and 150 minutes or more. The group doing nothing had more morning fatigue, less energy, and worse sleep. Walking was the activity people reported most.

Observational studies have linked activity to better survival in three cancers. NCI reports:

• Breast cancer. A 2019 review and meta-analysis compared the most active survivors with the least active. The most active had a 42% lower risk of death from any cause. They had a 40% lower risk of death from breast cancer.
• Colorectal cancer. Activity after diagnosis was associated with a 30% lower risk of death from colorectal cancer and a 38% lower risk of death from any cause.
• Prostate cancer. Limited evidence linked activity after diagnosis with a 33% lower risk of death from prostate cancer and a 45% lower risk of death from any cause.

NCI is careful about what these mean. Observational studies cannot fully separate exercise from other healthy habits that active people tend to share. Randomized trials are under way to settle it. They include BWEL in newly diagnosed breast cancer, CHALLENGE in colon cancer after chemotherapy, and INTERVAL-GAP4 in metastatic prostate cancer.

For other cancers the picture is thinner. NCI calls the evidence very limited for non-Hodgkin lymphoma, stomach cancer, and malignant glioma.

Check with your health care team before starting a program, and specifically if any of these apply to you:

• Heart or lung disease.
• An ostomy.
• Severe fatigue.
• Balance problems or unsteadiness on your feet.
• Weak bones, or cancer that has spread to bone.

Also ask whether any of your medicines affect how active you can be. That question gets skipped often. The answer sometimes changes the plan.

These are specific enough to act on:

• Do not exercise above a moderate level of exertion without talking to your doctor first.
• Skip exercise entirely on a day when you feel dizzy or unsteady.
• Avoid any activity that puts you at risk of a fall or an injury.
• Call your doctor right away for swelling, pain, dizziness, or blurred vision.
• Numbness in the feet or balance problems raises fall risk. Ask about devices that can help.

Tell your team about four things after a session: injury, pain, shortness of breath, or a longer recovery than usual. Those are the signals that the plan needs adjusting.

Before treatment. Being as active as possible may reduce complications from surgery. It may also help with distress and anxiety, energy, and sleep going in.

During treatment. The goal shifts from progress to holding ground. What you can do depends on your cancer type and stage, your treatment, and your fitness beforehand. If you exercised before, expect to do less or go lighter. If you were inactive, start small. Short, slow walks count. NCI names swimming, walking, yoga, and biking, or anything that gets the body moving. Never having exercised is not a barrier, and NCI says there are things a person can do even while stuck in bed.

As you recover. Most people can gradually increase time and intensity as side effects ease. A pace that feels light to a healthy person can feel hard after treatment. That is expected, not a failure.

With advanced cancer. Activity may still reduce fatigue and improve quality of life. It may make movement easier. How much you can tolerate depends on your cancer, your current ability, side effects, and other health problems. Clearance from the team comes first.

Some people manage on their own. Many do better with a certified trainer or a physical therapist who understands cancer treatment.

Two conditions apply. Check with your doctor before starting with a trainer or therapist. And make sure that person knows your diagnosis and any limits you have been given.

Three related pages go further. For what changes once treatment ends, see exercise after cancer treatment. For eating alongside activity, see nutrition during treatment. If numbness in your hands or feet is the barrier, see exercise with neuropathy. For the weeks in a cycle that need the most caution, see exercise when blood counts are low.

• American Cancer Society, Physical Activity and the Person with Cancer, accessed August 6, 2026
• National Cancer Institute, Physical Activity and Cancer, reviewed February 10, 2020; accessed August 6, 2026
• National Cancer Institute, Fatigue (PDQ) — Health Professional Version, accessed August 9, 2026
• National Cancer Institute, Day-to-Day Life: Keeping Your Daily Routine, accessed August 9, 2026