As living standards improve, exercise and fitness and staying in shape are becoming more and more important to people of all ages. On the other hand, with an aging population, the incidence of cancer is increasing. Soon after a diagnosis of cancer, many patients ask various questions, and exercise and fitness is one of the areas that people often focus on, such as: Should I exercise more? Should I gain weight or lose weight? Is there a specific risk of exercising for cancer patients? Cancer patients receive a wide range of advice from a variety of sources. However, this advice often comes from friends, family, patients, television and newspaper campaigns, overwhelming advertisements, and friendships, and is often unscientific and contradictory. To provide the most scientific answers to these questions, the American Cancer Society (ACS) brought together experts in the fields of nutrition, physical activity, and cancer to synthesize the latest scientific evidence and best clinical practices to develop guidelines for nutrition and physical activity in cancer patients. The guidelines are a summary of the most current and scientific findings on physical activity in cancer patients. Let us read the guidelines on physical activity for patients below. After diagnosis, cancer patients can be broadly divided into three stages: 1. active treatment and recovery; 2. recovery without disease or stable disease; 3. advanced stage with hospice care. At different stages, the exercise needs of cancer patients vary, and the lifestyle choices of cancer patients are of particular importance. During treatment and recovery, available evidence suggests that exercise is not only safe and feasible during cancer treatment, but can also improve physical function, relieve fatigue and fatigue, and improve quality of life. Some studies also suggest that physical activity may even increase the completion rate of chemotherapy. Choices about when to start and how to maintain physical activity need to be tailored to the patient’s condition and personal preferences. Patients receiving chemotherapy or radiation therapy may only be able to exercise at lower intensities or for shorter periods of time during treatment, but it should also be a good idea to maintain as much activity as possible. For patients who were sedentary prior to diagnosis, low-intensity activities, such as stretching and slow walking, should be adopted and gradually increased. For older individuals, those with bone metastases or osteoporosis, or severe injuries such as arthritis or peripheral neuropathy, balance and safety should be observed to reduce the risk of falls and injuries. Regular physical activity is essential during the recovery period after treatment to aid in the recovery and fitness enhancement process. During the disease-free or disease-stabilized period after recovery, maintaining an appropriate weight, being physically active and eating a healthy diet are important to promote overall health, improve quality of life and extend life expectancy. Exercise can improve cardiovascular function, increase muscle strength, reduce fatigue and fatigue, and relieve anxiety and depression, which can benefit patients’ physical and mental health and significantly improve their quality of life. A large number of prospective observational studies have shown that active cancer patients have a lower risk of cancer recurrence and higher survival rates than less active cancer patients. For people with advanced cancer, nutrition and physical activity recommendations are best based on individual nutritional needs and physical abilities. Currently, overweight and obesity are becoming more common. Studies have found that overweight and obesity are significantly associated with the risk of many cancers, including breast cancer, colon and rectal cancer, endometrial cancer, kidney cancer, and pancreatic cancer in postmenopausal women. Obesity may also be associated with an increased risk of gallbladder cancer and may also be associated with liver, cervical and ovarian cancers and non-Hodgkin’s lymphoma. As a result, many cancer patients are already overweight or obese at the time of diagnosis. There is growing evidence that being overweight increases the risk of cancer recurrence and decreases the survival time of patients. For patients who are normal weight at diagnosis, overweight or obese, it is important to avoid weight gain during treatment, and overweight and obese individuals are more likely to benefit from weight loss. For patients who are malnourished at diagnosis or during treatment, further weight loss may impair quality of life, interfere with completion of treatment, delay wound healing, and increase the risk of complications, and should be carefully assessed in terms of dietary intake and factors affecting energy expenditure to achieve a positive energy balance leading to weight gain. The most common indicator of normal weight is body mass index (BMI), which is calculated by dividing body weight (kg) by the square of height (m), and the result is healthy between 18 kg/m2 and 24 kg/m2. It is recommended that cancer patients maintain their body weight within the normal range. Numerous studies have demonstrated that physical activity after cancer diagnosis can reduce the risk of cancer recurrence and improve overall survival in a variety of cancers (including breast, colorectal, prostate and ovarian). Considering the peculiarities of cancer patients’ physique, the following things need to be noted in exercise: 1. Patients with severe anemia should delay exercise (except for activities of daily living) until the anemia is corrected. 2. Patients with impaired immune function should avoid activities in public places until their white blood cell counts return to safe levels. Survivors who have completed a bone marrow transplant are usually advised to avoid such exposure for one year after transplantation. 3. For patients with severe fatigue and weakness, they may be encouraged to do 10 minutes of light exercise daily. 4. Patients undergoing radiation therapy should avoid irradiated skin contact with chlorine (e.g., swimming pools). 5.Patients with indwelling catheters or nutrient tubes should avoid catheter contact with swimming pools, lakes, seawater or other factors that may lead to infection, as well as activities to the muscles in the catheter area to avoid catheter slippage. 6. Patients with other comorbidities need to consider the effects of other diseases and are advised to consult a specialist. 7. Patients with significant peripheral neuropathy or ataxia may have reduced mobility due to weakness or poor balance and should choose an appropriate activity program to avoid causing injury. The guidelines recommend returning to normal activity as soon as possible after diagnosis or treatment. adults aged 18 to 64 years should engage in at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic physical activity per week. Moderate-intensity activities include brisk walking, slow cycling, slow swimming, rowing, baseball throwing, softball, volleyball, and doubles tennis, and are simply judged by the ability to talk and chat, but not sing, during the activity. High-intensity aerobic physical activities include fast cycling, plowing, hiking, rope skipping, martial arts, race walking, jogging, basketball, soccer, fast swimming, singles tennis, etc. A simple way to judge is to be able to speak only a few words in short sentences during the activity, but not to speak and chat. Even if you cannot complete the above-mentioned intensity activities in full, performing a small amount of activities can bring benefits. As much activity as physical strength allows, more activity than the above can bring additional benefits. Each activity should last at least 10 minutes and be spread as evenly as possible throughout the week. In addition, adults should perform muscle-strengthening exercises involving all major muscle groups at least 2 days per week. Adults over the age of 65 should also follow these recommendations as long as their physical strength allows. If chronic conditions limit activity, older adults should try to perform as much physical activity as they can and avoid prolonged physical inactivity. It is important to clarify that the above physical activity recommendations are an important complement to standard cancer treatment and do not imply that physical activity is more important than other methods of treatment and care. The promotion of physical health through appropriate activity is predicated on the standardized treatment of cancer. And, just as treatment options vary depending on the type of cancer and the patient’s own circumstances, physical activity factors affect different types of cancer and different patients differently. In addition, the above guidelines are oriented to American cancer patients. Considering the great differences between China and the United States in terms of ethnicity, economic level, living customs and social ethos, the above recommendations are for reference only and must be combined with the specific situation in China in practice. According to statistics, only less than 10% of cancer patients during treatment have reached the recommended level of physical activity, and only about 20% to 30% of patients are actively physically active during the post-treatment recovery period. Therefore, there is still a long way to go to be physically active among cancer patients.