Strengthening During and After Cancer

Author: Lora Packel, PT, PhD, Associate Dean of the School of Health Professions at Saint Joseph’s University

Last Reviewed: December 30, 2025

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Disclaimer: You should discuss your health risks with your provider before starting any exercise program.

What can cause weakness during and after cancer treatment?

Strength training is an excellent addition to your exercise routine during and after cancer treatment. Cancer treatments and their side effects can have an impact on your muscles and bones while it does its job in attacking your cancer.

Some things that can lower your strength or bone density during the cancer experience are:

Cancer treatments: Some of the essential cancer treatments also have side effects that impact your muscles and bones. Some chemotherapy agents affect your muscles, contributing to weakness. Steroids, especially if given in high doses or for long periods, cause muscle weakness and lower the strength of your bones.
Changes in diet or nutrition: During treatment, you may experience changes in your diet due to altered taste, nausea, or diarrhea. Your muscles may lose strength if they don’t receive the protein, vitamins, and minerals necessary for muscle maintenance or growth.
Being less active: Lower amounts of your regular activity may cause your muscles to lose strength and endurance. This is common as people experience fatigue from cancer treatments or lack time due to the frequency of medical appointments leaving less time for activity.

What can cause your bones to weaken during cancer treatments?

Some things that can lower your bone density during the cancer experience are:

Cancer treatments: Some treatments can weaken your bones while also fighting cancer. Hormone-lowering or blocking agents that are sometimes used to treat prostate cancer, breast cancer, and other types of cancers can have a side effect of weakening bones.
Changes in diet or nutrition: During treatment, you may experience changes in your diet or nutrition due to altered taste, nausea, or diarrhea. Dietary changes, vomiting, or diarrhea can cause loss of muscle strength and lower your bone density. Muscles pull on bones when they contract, and this is one of the mechanisms that maintain the strength of bones. If muscle is lost, it will impact bone strength.
Being less active: Lower amounts of your regular activity will contribute to the weakening of bones. Bones require force as the signal to maintain their strength. “Force” can be things like weight-bearing exercises where one puts weight through their arms or legs (e.g. walking). The lower one’s activity levels, the lower the signals to your bones to keep them strong.

What are the benefits of strength training?

Making your bones stronger (increased bone density).
Preventing loss of muscle during treatment and increasing it afterward.
Reducing the amount of fat in your body.
Reducing levels of cancer-related fatigue.
Improving overall health-related quality of life.
Might improve sleep when combined with aerobic training.
May improve anxiety and depression when combined with aerobic training.

There will be days when you should not do strength-training exercises.

Strength training should not be done when your platelet count is below 50,000 due to the risk of bleeding.
Strength training should not be done if you feel off balance or dizzy.
If you have metastases (cancer that has spread) to your bones or primary bone cancer, you should discuss the safety of strength training with your oncologist before beginning any program.
If you have balance problems, you should perform exercises under the supervision of a physical therapist

Will lifting weights cause lymphedema?

A supervised strength training program with a slow gradual progression of weights has not been shown to cause or worsen lymphedema.⁵ Those with breast cancer who have lymphedema or who are at risk of lymphedema should consult with a lymphedema specialist before starting a strength training program.

How do I get started with strength training?

To increase your muscle strength, you need to OVERLOAD the muscles. This means using a weight that makes the exercise difficult, but not impossible! In the beginning, you may choose to use light weights or no weights at all and work your way up to weights. You should follow the general principle of starting with low resistance and progressing slowly.

Strength training can be done with or without equipment at home or at a gym. If you’ve never lifted weights before, you should consider working with a physical therapist or exercise specialist who has experience working with people who have cancer. The American Physical Therapy Association has a database of therapists who have an oncology specialty, and the American College of Sports Medicine has a list of exercise specialists who have additional training related to working with those who have cancer.

For whole-body strength training, find exercises that target multiple muscle groups in one exercise.

How often?

Aim for a minimum of 2 days per week, with a rest day in between sessions.

How much weight should I lift?

With the help of an exercise specialist, you can perform a 1 rep max exercise. This is the maximum amount of weight that you can lift with good form only one time. Once you have that number, you can follow the recommendations below.

Stage I: If you’ve never lifted weights before or haven’t lifted in a long time, pick a weight that is about 40-50% of your 1 rep max weight.

When you can perform the repetitions with ease or if you can perform more than the repetitions you’ve planned, it’s time to increase the weight!

Stage II: Once you can perform 15 repetitions at the state I weight with ease, you can increase the weight to 55-65% of 1 rep max.

When you can perform the repetitions with ease or if you can perform more than the repetitions you’ve planned, it’s time to increase the weight!

Stage III: Once you can easily perform 15 repetitions at the stage II weight, increase to 65-75% of your 1 rep max weight.

How many times should I repeat each exercise?

You should rest for 1-2 minutes between each set of 15 repetitions and perform the exercise 2-3 times.

The last repetition should be hard to complete and your muscles should be tired.

Thanks to oncology rehabilitation researchers and guidelines from the American College of Sports Medicine⁶, we now know more precise strength training amounts that you should perform to alleviate some common things that people with cancer experience. Visit these guidelines here.

To improve energy levels and reduce cancer-related fatigue:

Strength training 2 times per week.
Perform 2 sets (repeat the exercises 2 times).
In each set, lift the weight 12-15 times (repetitions or reps).
Perform strength training at a moderate intensity.

To improve health-related quality of life:

Strength training 2 times per week.
Perform 2 sets.
In each set, lift the weight 8-15 times (reps).
Perform strength training at a moderate to vigorous intensity.

To improve physical function:

Strength training 2-3 times per week.
Perform 2 sets.
In each set, lift the weight 8-12 times (reps).
Perform strength training at a moderate to vigorous intensity.

The following exercises can be modified to adjust for any muscle or bone issues that you may have (i.e., low back pain, osteoarthritis, etc.). They can also be modified to increase the difficulty should you need more challenges. If you need assistance with exercises or guidance, seek out a physical therapist who specializes in cancer rehabilitation.

Find a PT: https://aptaapps.apta.org//APTAPTDirectory/FindAPTDirectory.aspx