Exercise as it relates to Disease/Exercise interventions to improve physical fitness and decrease markers of oxidative stress amongst cancer patients

The following critical analysis is devoted to the journal article "oxidative stress and fitness changes in cancer patients after exercise training" by Chris P. Repka and Reid Hayward(2016)[1]

What is the background to this research?


Cancer patients are consistently worn down physically by the manifestation of cancer cells in their body. Due to the rapid growth of these cancerous cells around the body,the body is influenced negatively which causes muscle wastage, decrease in cardio respiratory fitness and oxidative stress increases. Muscle mass declines due to the cytokine cells in the body that activate in response to cancer cells infiltrating the body which leads to weight loss, muscle loss and decrease in appetite[2]. Therefore the process of catabolism takes place in the body which is known as muscle wastage. catabolism occurs due to the weakened ability of cancer patients to maintain their natural homeostasis in protein synthesis and protein degradation as their immune system defends against foreign cancer cells [3]. In addition to this, a method of destroying cancer cells known as chemotherapy also causes damage to the body. Chemotherapy further contributes to the constant degradation of muscle mass, including the induced side effects of nausea and physical exhaustion. Following these poor physical conditions induced by cancer, the patient becomes more physically fatigued which leads to a sedentary lifestyle[2][3]. Oxidative stress is also a factor that contributes to the rapid growth of cancer cells in the body. Cancer cells can potentially multiply in the body due to an over production of free radicals[4]. The imbalances of the body’s antioxidants and immune defenses causes free radicals to damage cellular proteins, cause DNA injury and inflammation of various bodily tissues[4]. This leads to damaged cells of the body being exposed to cancer cell proliferation[4]. The purpose of this journal article is to discover the beneficial outcomes of implementing exercise routines for cancer patients. The desired results were to find decreased markers of oxidative stress, improved muscle mass and cardiovascular fitness in cancer patients while comparing their results to healthy individuals[1].

Where is the research from?


This study was conducted by the department of health sciences in the University of Northern Arizona. There are no conflict of interests disclosed by either authors of this article which also received no funding. One of the main authors of this journal article is a notable PHD professor in the University of Arizona who possesses expertise in the fields of exercise sport science and rehabilitation. His life studies have boasted 23 different research citations that he has been involved with including this journal article. His profile can be found in the following hyperlink[5].

What kind of research was this?


This experiment was a randomized control trial. This experiment had a control group of cancer patients that underwent physical activity for a period of 10 weeks. The healthy individuals completed a standard care routine. The variables being tested are the different advances in physical health between the two control groups[6].

What did the research involve?


15 cancer patients and 7 healthy individuals with no history of chronic illnesses were chosen for the 10 week study [1]. The subjects were also age matched to each other to avoid any bias and contradictions of the study results. A single baseline blood extraction from healthy individuals were required due to their healthy oxidative stress values [1]. The Cancer positive participants were required to extract blood pre and post testing due to the oxidative stress they induce from radiation and chemotherapy treatment [1]. There were less cancer patients to test due to the severity of their physical in-capabilities induced by their stages of cancer which hindered their participation in the study. in addition to this, other cancer participants did not meet the participation standards required for the experiment. The inclusion criteria of both cancer and non-cancer patients were that they do not consume supplementation that boosts their immune system and also did not smoke[1]. A 1mph (1.6kmph) treadmill exercise was administered to the cancer patients for 10 weeks with a gradual increase of workload throughout. Their blood pressure and heart rate were recorded while also being encouraged to exercise until fatigue. Blood pressure was recorded every 3 minutes of exercise, during rest and post exercise in recovery [1]. Muscular strength assessment was made with a 1 repetition max test. In addition to this cancer patients were required to choose a weight resistance for the muscle groups they were testing that causes muscle failure in repetitions of 4 – 6 to observe improvements[1]. Every day exercise interventions consisted predominantly of:

• 5 minute warm ups

• 25 minutes of aerobic exercise

• 25 minutes of resistance training

• 5 minutes of flexibility and balance training

Blood handling and analysis was extracted to discover the activity of antioxidant capacity and oxidative stress [1]. All of the accumulated physical tests of both cancer and non-cancer patient control groups were calculated through statistical analyses using independent t-tests[1]. This methodology of using Randomized control trials for this study is the most effective tool. It is predominantly used for clinical researches that provide clear evidence for improving the quality of life of people suffering from chronic illnesses [6].



The limitations of this study was that there were a large number of cancer patients who could not continue the experiment. It would have improved the reliability of the study if there were a sufficient number of subjects that participated in this study. There was also no dietary alteration follow ups which could have possibly implicated the outcome of the experiment further.

What were the basic results?


As hypothesized, the outcomes of the exercise intervention proved beneficial for the cancer patients:

• Exhibited lower markers of oxidative stress

• Increased muscular mass

• Increase in antioxidant capacity to help fight free radicals

• Increase in cardiovascular fitness

These results are further supported by the study conducted by Galvao et al, which demonstrated that exercise routines for cancer patient’s improves their quality of life, less muscle wastage and improved mental health[7].

What conclusions can we take from this research?


This research demonstrated strong evidence of how exercise positively affects a cancer patient’s quality of life. A prescribed training schedule that involves a combination of aerobic and resistance training can potentially improve a cancer patients physical and mental health. This is opposed to leading a sedentary lifestyle which causes detrimental effects to the body such as an increased rate of muscle catabolism and decline of physical capabilities. A similar study that supports the results of this research was conducted by Hayes et al, which proved that prescribed exercises modules for cancer patient populations increases their overall muscular functionality and enhances their quality of life[8].

Practical advice


This research provides clear evidence that physical activity amongst cancer patients is imperative for them to live longer and improve their physical health. Moderate to high intensity resistance and aerobic training is the most effective method for maintaining physical health. By implementing exercise routines into the daily routine of cancer patients, they are able to live longer and reduce the severity of the symptoms they experience from chemotherapy. This includes the possibilities of slowing down the process of cancer cells spreading throughout the body while simultaneously reducing the body fatiguing side effects as well.

Further information and resources


For further information on the effects of physical activity on cancer, read the following reading materials:





1. REPKA C, HAYWARD R. Oxidative Stress and Fitness Changes in Cancer Patients after Exercise Training. Medicine & Science in Sports & Exercise. 2016;48(4):607-614.

2. Cancer, Weight Changes, Muscle Loss, Fatigue | CancerCare [Internet]. CancerCare. 2016 [cited 17 September 2018]. Available from: https://www.cancercare.org/publications/140-coping_with_cancer-related_weight_changes_and_muscle_loss

3. Aversa Z, Costelli P, Muscaritoli M. Cancer-induced muscle wasting: latest findings in prevention and treatment. Therapeutic Advances in Medical Oncology. 2017;9(5):369-382.

4. Uttara B, Singh A, Zamboni P, Mahajan R. Oxidative Stress and Neurodegenerative Diseases: A Review of Upstream and Downstream Antioxidant Therapeutic Options. Current Neuropharmacology. 2009;7(1):65-74.

5. Chris P Repka [Internet]. Research Gate. 2018 [cited 18 September 2018]. Available from: https://www.researchgate.net/profile/Chris_Repka

6. Melissa Conrad Stöppler M. Clinical Trials: Read About Phases, Testing, and Types [Internet]. MedicineNet. 2018 [cited 19 September 2018]. Available from: https://www.medicinenet.com/clinical_trials/article.htm#clinical_research_and_clinical_trials_facts

7. Galvão D, Newton R. Review of Exercise Intervention Studies in Cancer Patients. Journal of Clinical Oncology. 2005;23(4):899-909.

8. Hayes S, Spence R, Galvão D, Newton R. Australian Association for Exercise and Sport Science position stand: Optimising cancer outcomes through exercise. Journal of Science and Medicine in Sport. 2009;12(4):428-434.

9. What is cancer? [Internet]. Cancer Research UK. 2018 [cited 20 September 2018]. Available from: https://www.cancerresearchuk.org/about-cancer/what-is-cancer

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