Benefits of Exercise as an Adjuvant Therapy for Cancer: A Study on Safe Training During Chemotherapy

Preface: A Scientific Bridge from the Laboratory to Taiwan’s Roads

Cancer treatment was once thought to require “more rest, less activity,” but this notion has been overturned by evidence. A growing body of research shows that moderate exercise can be performed safely during treatment, significantly improving cancer-related fatigue, physical function, and quality of life, and may even influence prognosis for certain cancers. Exercise is shifting from “post-treatment rehabilitation” to “adjuvant therapy during treatment.” This article analyzes the role, mechanisms, and safety principles of exercise in cancer adjuvant therapy.

Exercise Against Cancer-Related Fatigue

Cancer-related fatigue is the most common and distressing side effect of treatment, and paradoxically, exercise—rather than rest—is the most evidence-based countermeasure. Multiple meta-analyses show that aerobic and resistance exercise moderately improve cancer-related fatigue, with effects superior to medication and rest alone. The ACSM Roundtable on Exercise and Cancer confirmed the benefits of exercise on fatigue, quality of life, physical function, and certain psychological indicators, and proposed safe exercise guidelines, making exercise a component of cancer care.

Mechanisms and Prognostic Impact

The mechanisms by which exercise benefits cancer patients include: counteracting treatment-induced muscle loss and deconditioning, reducing chronic inflammation, improving immune surveillance (NK/T cells), modulating hormones (such as estrogen in breast cancer), and improving metabolic and insulin pathways. Epidemiological studies show that patients with breast cancer, colorectal cancer, and others who exercise regularly after diagnosis have lower risks of recurrence and mortality. Although more randomized trials are needed to confirm causality, the associations are consistent and the mechanisms are plausible, supporting exercise as an adjunctive strategy.

Safe Training Principles During Chemotherapy

Exercise during treatment requires individualization and safety precautions: adjust or pause based on blood counts (e.g., severe anemia, very low platelets, neutropenia), avoid crowded places when infection risk is high, watch for balance impairment from peripheral neuropathy, and flexibly adjust intensity based on daily condition. The principle is “moving is better than not moving, but move smartly”: low-to-moderate intensity, gradual progression, and listening to your body. Exercise should be conducted under joint assessment by oncology and exercise professionals, not as self-directed intense training.

Possible Mechanisms of Exercise Against Cancer: From Inflammation to Immune Surveillance

The mechanistic hypotheses for how exercise influences cancer prognosis are multifaceted. Anti-inflammatory: exercise reduces chronic inflammation, which is a promoter of tumor growth and metastasis. Immune surveillance: exercise mobilizes and activates NK cells and cytotoxic T cells, potentially enhancing the clearance of tumor cells. Hormonal: exercise modulates estrogen, insulin, and IGF-1, which are associated with the risk of breast and colorectal cancers. Metabolic: improves insulin sensitivity and reduces visceral fat, lowering a pro-tumorigenic metabolic environment. Additionally, exercise counteracts treatment-induced muscle loss and cardiopulmonary deconditioning. Together, these mechanisms support the biological plausibility of exercise as an adjunctive strategy in cancer care. Although the causal link between exercise and improved prognosis still requires more randomized trials, the consistency of mechanistic and epidemiological evidence is sufficient to support incorporating exercise into cancer care.

Implementing Exercise Prescriptions in Oncology Care

Putting “exercise as medicine” into practice in oncology care requires interdisciplinary collaboration and individualization. Guidelines proposed by the ACSM and others recommend that most cancer patients should avoid sedentary behavior and aim to meet weekly aerobic and resistance exercise targets, but with adjustments based on treatment phase, side effects, and individual circumstances. In practice: flexibly adjust during chemotherapy based on blood counts, watch for infection and bleeding risks, be mindful of balance issues from peripheral neuropathy, and use subjective tolerance as the guide. In terms of exercise types, low-impact cycling (including indoor trainers), walking, and water-based exercise are suitable for patients with limited physical capacity. The ideal model is joint design and supervision by oncology, rehabilitation medicine, and exercise professionals. The goal is not athletic performance, but maintaining function, improving fatigue and quality of life, and supporting treatment tolerance and recovery.

Levels of Evidence for Exercise and Cancer: A Cautious Interpretation

Evidence on exercise and cancer must be interpreted in layers with caution. The evidence for improving “cancer-related fatigue, physical function, and quality of life” is strongest (from multiple randomized controlled trials and meta-analyses) and is sufficient to support incorporating exercise into cancer care. The evidence for influencing “cancer prognosis (recurrence, survival)” is largely observational—those who exercise after diagnosis have better outcomes, but it is difficult to fully exclude reverse causation (healthier individuals are more able to exercise), and causality requires more randomized trials to confirm. Therefore, a clear distinction should be made: exercise improving symptoms and quality of life during treatment is “established,” while improving survival is “promising but requires more evidence.” This layered interpretation avoids overpromising (such as claiming “exercise can cure cancer”) while affirming the clear value of exercise as an adjunct. The practical message for cancer patients is: moderate exercise is safe and can significantly improve fatigue and quality of life during treatment, and is worth incorporating under professional guidance, while its potential benefit on prognosis is an additional, encouraging possibility.

Interdisciplinary Perspective: Integrating Oncology and Sports Medicine

Research on exercise in cancer adjuvant therapy represents an important advance at the intersection of oncology and sports medicine, elevating exercise from “post-treatment rehabilitation” to “adjuvant therapy during treatment.” It overturns the old notion that “cancer treatment requires rest,” demonstrating that moderate exercise is safe during treatment and significantly improves cancer-related fatigue, physical function, and quality of life. The value of this interdisciplinary integration lies in providing cancer patients with a powerful adjunctive strategy beyond medication. From a symptomatic perspective, exercise is the most evidence-based countermeasure for cancer-related fatigue; from a mechanistic perspective, exercise is anti-inflammatory, improves immune surveillance, modulates hormones and metabolism, and counteracts muscle loss; from a prognostic perspective, regular exercise after diagnosis is associated with lower risks of recurrence and mortality (though more RCTs are needed to confirm causality). This perspective extends “exercise as medicine” into oncology care, reflecting the role of exercise in managing chronic and major diseases. It requires interdisciplinary collaboration—oncology, rehabilitation medicine, and exercise professionals jointly designing individualized, safe programs. For Taiwan, with its high cancer incidence, this integration carries significant meaning: moderate exercise can improve quality of life during treatment and support recovery, and deserves to be incorporated into routine cancer care.

From Research to Clinical Practice: An Action Framework for Cancer Exercise Rehabilitation

Integrating exercise into cancer care can follow the framework of “dispelling myths—individualization—safety precautions—sustained recovery.” Dispelling myths: during treatment, “moderate exercise is better than rest alone,” and exercise has evidence-based benefits for cancer-related fatigue, physical function, and quality of life; patients should not remain completely inactive out of fear of fatigue. Individualization: design programs based on cancer type, treatment phase, side effects, and individual circumstances, combining aerobic training (improving cardiopulmonary function, reducing cardiovascular risk), resistance training (counteracting muscle loss), and mobility work; low-impact cycling (including indoor trainers), walking, and water-based exercise suit those with limited physical capacity. Safety precautions: adjust based on blood counts (modify or pause with severe anemia, very low platelets, or neutropenia), avoid crowded places when infection risk is high, and watch for balance impairment from peripheral neuropathy; exercise should be assessed and supervised jointly by oncology, rehabilitation medicine, and exercise professionals, not self-directed intense training. Sustained recovery: rebuild physical capacity at low-to-moderate intensity with gradual progression; continuing regular exercise after recovery is associated with better prognosis. For Taiwan’s healthcare system, promoting “exercise as medicine” in oncology care is an important direction. The core of this framework is: under professional oversight, moderate exercise becomes a safe adjunct for cancer patients to improve quality of life, support treatment tolerance, and aid recovery.

Local Application in Taiwan: Climate, Events, and Cultural Context

Taiwan has a high cancer incidence rate and a large number of cancer patients, creating an urgent need for exercise rehabilitation. These studies convey an important message: during cancer treatment, “moderate exercise is better than rest alone,” improving fatigue and quality of life. Cycling (especially indoor trainers or flat routes) and walking are ideal low-impact, intensity-controllable options suitable for cancer patients with limited physical capacity. It is recommended that Taiwan’s healthcare system promote “exercise as medicine” in oncology care, with oncology, rehabilitation medicine, and exercise professionals jointly designing personalized programs. Cancer patients should, under professional assessment, rebuild physical capacity at low-to-moderate intensity with gradual progression, incorporating exercise into their recovery.

Taiwan’s high cancer incidence and large patient population create an urgent demand for exercise rehabilitation. These studies deliver a clear message: moderate exercise during treatment is better than rest alone. It is recommended that Taiwan’s healthcare system promote “exercise as medicine” in oncology care, with interdisciplinary teams designing personalized programs; cancer patients should rebuild physical capacity at low-to-moderate intensity with gradual progression, incorporating cycling and walking into recovery, and continue exercising after recovery to support long-term prognosis.

Frequently Asked Questions and Myth Clarification

Myth 1: Cancer treatment requires more rest and less activity? This has been disproven. Moderate exercise is better than complete rest, as it can improve cancer-related fatigue, physical function, and quality of life without worsening the condition.

Myth 2: Can exercise cure cancer? Exercise is adjunctive, not curative. Its benefits for improving symptoms and quality of life are well-established, while its impact on prognosis is promising but requires further research. These claims should not be overstated.

Myth 3: Is it completely impossible to exercise during chemotherapy? It is possible, but it must be individualized—adjusted according to blood cell status, avoiding environments with infection risk, and performed at low-to-moderate intensity under professional assessment.

How to Read Exercise Science Research: Developing Evidence Literacy

This article cites four studies from top international journals (such as Journal of Applied Physiology, Medicine & Science in Sports & Exercise, Sports Medicine, Nature, and the Cell series), but as a reader, cultivating “evidence literacy” can help you absorb this knowledge more rationally rather than accepting it at face value. First, distinguish study types: randomized controlled trials (RCTs) have the strongest causal inference, observational studies (cohort, cross-sectional) can only show associations rather than causation, and animal and cellular studies reveal mechanisms but require caution when translating to humans. Second, pay attention to samples and contexts: results from small samples or specific populations (such as elite athletes or particular age groups) may not apply to you; studies predominantly based on European and American populations also warrant consideration regarding their applicability to Taiwanese populations. Third, value effect size rather than merely looking at “statistical significance”: statistical significance does not equal a practically meaningful benefit; you must ask, “Is this difference important in real-world training or health terms?” Fourth, be wary of over-extrapolation and commercialization: preliminary findings from a single study are often exaggerated into “miraculous” products or methods; you should wait for replication and systematic reviews. Fifth, make holistic judgments based on the “consistency” of mechanistic, associational, and interventional evidence, rather than rejecting everything because of flaws in a single study or accepting everything because of a single impressive result. Sixth, understand that “individual variability” is the norm in exercise science: the same intervention produces different responses in different people due to genetics, training background, lifestyle, and environment; research presents group averages, so when applying findings to yourself, be sure to observe your own actual responses and adjust accordingly. Seventh, prioritize the “fundamentals”: sleep, nutrition, consistent training, and recovery—these basics with abundant evidence and clear benefits—should always take precedence over novel supplements, equipment, or methods; many seemingly sophisticated interventions offer marginal benefits far smaller than getting the basics right. Exercise science is a constantly evolving field; maintaining an open yet critical attitude, updating your knowledge as evidence evolves, while respecting individual variability and valuing fundamentals, is the only way to truly translate cutting-edge research from international journals into training and health decisions that are useful, safe, and sustainable for you—without blindly following trends or deferring to any single authority.

Key Takeaways from This Article

Synthesizing the interdisciplinary research and mechanistic analyses above, the core points can be distilled as follows: Exercise is better than complete rest during treatment: moderate exercise has empirical evidence for improving cancer-related fatigue and quality of life. Low-to-moderate intensity, progressive approach: listen to your body and adjust flexibly based on daily condition. Requires professional collaboration: adjust according to blood cell status and other factors, with assessment by oncology and exercise professionals. Cycling/walking is suitable for cancer patients: low-impact, controllable intensity, rebuilding physical fitness. Continued exercise after recovery: regular exercise is associated with better prognosis, and long-term adherence is beneficial. Behind these points lies the convergence of multiple fields—sleep science, immunology, genomics, neuroscience, microbiology, endocrinology, and data science—which together convey a core message: the benefits and adaptations of exercise are the integrated result of multiple body systems working in coordination, not something captured by any single factor. Understanding this interdisciplinary, integrative perspective helps us move beyond fragmented “treat-the-symptom” thinking and approach training, recovery, and health in a more comprehensive way. Only by incorporating these principles into daily training and life, and dynamically adjusting them according to individual circumstances, actual responses, and professional advice, can we translate cutting-edge findings from top international journals into practices that are truly feasible, safe, and sustainable within Taiwan’s climate, racing calendar, and lifestyle context. The ultimate value of exercise science lies in helping every athlete—elite or amateur, young or old—exercise smarter, healthier, and with greater enjoyment, achieving both physical and mental growth in the process.

Practical Recommendations for Taiwanese Athletes

1. Exercise is better than complete rest during treatment: moderate exercise has empirical evidence for improving cancer-related fatigue and quality of life.
2. Low-to-moderate intensity, progressive approach: listen to your body and adjust flexibly based on daily condition.
3. Requires professional collaboration: adjust according to blood cell status and other factors, with assessment by oncology and exercise professionals.
4. Cycling/walking is suitable for cancer patients: low-impact, controllable intensity, rebuilding physical fitness.
5. Continued exercise after recovery: regular exercise is associated with better prognosis, and long-term adherence is beneficial.

Research Citations and Further Reading

• Schmitz, K. H., et al. (2019). Exercise is medicine in oncology. CA: A Cancer Journal for Clinicians, 69(6), 468–484.
• Campbell, K. L., et al. (2019). Exercise guidelines for cancer survivors. Medicine & Science in Sports & Exercise, 51(11), 2375–2390.
• Cormie, P., et al. (2017). The impact of exercise on cancer mortality, recurrence, and treatment-related adverse effects. Epidemiologic Reviews, 39(1), 71–92.
• Mishra, S. I., et al. (2012). Exercise interventions on health-related quality of life for cancer survivors. Cochrane Database of Systematic Reviews.

This article is a translation of exercise science knowledge. Individual physiological responses vary; please consult professional coaches and sports medicine physicians before making any training or intervention adjustments, and proceed gradually according to your personal health status.

Related Topic Reading

• Cycling Rehabilitation After Cancer Treatment: The Two-Wheeled Path to Rebuilding Fitness and Confidence
• The Anti-Cancer Mechanisms of Aerobic Training: Research on Exercise-Induced Changes in the Tumor Microenvironment
• Exercise and Cancer: From Prevention to Recovery—A Sports Science Consultant’s Practical Prescription and Training Plan
• Cancer Prevention Benefits for Cyclists: Research on Regular Aerobic Exercise Reducing the Risk of Multiple Cancers