Exercise as it relates to Disease/Aerobic Exercise can Increase Physical and Mental Health in Men with Bone Metastatic Prostate Cancer

What is the background to this research?
This study conducted by Zopf E et al. 2016 examines the relationship of aerobic exercise in men with bone metastatic prostate cancer. Bone metastases is a side effect of advanced prostate cancer. This disease can impair mobility, increase the risk of bone fractures and cause significant body pain. This is the first study to examine bone metastatic prostate cancer and aerobic exercise, as previous studies have excluded this population due to their risk of bone fractures. This research looks to assess the clinical benefits of aerobic exercise, and its effect in increasing quality of life and physical capabilities, for future therapies and supportive methods. The study also compares patients who are inactive, to those meeting the aerobic exercise guidelines, and their perceived quality of life and physical function.

Where is the research from?
This study was conducted on an Australian population in Perth at the Edith Cowan University’s Exercise Medicine Research Institute. This Institute examines the relationship of exercise and cancer. It is funded by the National Health and Medical Research Council.

All authors work within the field of exercise and oncology and have a good reputation, both nationally and internationally. Most authors are from the Exercise Medicine Research Institute, such as the director Dr Daniel Galvão.

This study was funded by the Prostate Cancer Foundation of Australia. This study had no conflict of interest.

What kind of research was this?
This study was a preliminary random control trial. Participants were referred by a Perth Urologist or Oncologist, as part of an ongoing cross-sectional RCT with the Exercise Medicine Research Institute.

As this was the first study to include participants with bone metastases, evidence in this area are minimal. However, other research on aerobic exercise and prolonged prostate cancer survival, have shown a positive association.

What did the research involve?
Data from this study, such as a the 400m and 6m walk test and timed up and go test, were used from a cross-sectional baseline data bank, reported from other RCT’s within this population.

Significant to this study, the participants had to self-report their physical activity levels from the previous month. This was completed by filling out the Modified Godin Leisure-Time Exercise Questionnaire. The time spent doing low, moderate and vigorous activity was calculated in minutes, and was compared to ACSM cancer survival exercise recommendations. Participants who met the exercise guidelines, accumulated over ≥150 minutes/per week.

Participants had to also self-report aspects of their quality of life. This included, body pain, social, physical and role functioning and mental and general health. They did this through The Medical Outcomes Study 36- Item Short-Form Health Survey (SF-36).

Body composition was measured using waist and hip circumference and a DEXA scan. Participants prostate-specific antigen level were also measured.

This methodology was not the best approach. Using self-reported data can over/under report the results, which may not be a true representation of the population, causing limitations.

Limitations
The referred participants had to meet a certain criterion to be eligible for this study. Participants had to be clear of acute illnesses/diseases which could be affected by exercise. They were excluded if they already participated in a supervised exercise program, couldn’t speak and read English and had to have evidence of bone metastases in their last scan.

Of the 103 participants screened, 46 participants were excluded from the data set. This specific criterion, and exclusion, may hinder the true representation of this population.

Using cross-sectional baseline data, limits the reasoning behind the results. For example, the study couldn’t explain why participants, of similar body pain, are meeting the exercise guidelines while others are not.

What were the basic results?
The important findings were:
 * The participants who met the aerobic exercise guidelines had a higher self-reporting of general health, emotional and physical functioning.
 * Participants who met the aerobic guidelines had a better 400 and 6-meter walk, compared to patients who didn’t meet the guidelines.
 * Participants who met the guidelines also had better hip and waist circumference, compared to the participants that didn’t meet the guidlines.

Therefore, meeting the exercise guidelines may be significant in preserving health with prostate patients with bone metastases.

However, due to the small, self-reported, participants that met the aerobic exercise guidelines, the author may have overly emphasised the important results.

What conclusions can we take from this research?
Aerobic exercise can improve mental health and physical functioning in men with bone metastatic prostate cancer. However, as this study excluded participants in a supervised exercise program, or in a more disease state, it can’t assume that this is the case for all prostate patients with bone metastases.

These results are consistent with newer studies, where both found aerobic or multi model exercise, in prostate patients with bone metastases, was linked to an increase physical and mental health outcome.

Practical advice
Even though the study had a small sample size, they still showed that the participants who engaged in aerobic exercise, experienced better mental and physical outcomes, even though bone pain was similar across all participants. This finding could encourage people with bone metastases, to engage in aerobic exercise, to improve their physical function and mental health, a common side effect of the disease.

However, more research is needed on what type of aerobic modalities are appropriate for this population, with emphasis on fracture prevention and unnecessary bone loading/tension. Frequency, intensity and time of the exercise bout also needs to be explored, to prevent symptoms of chronic fatigue and excessive bone and muscle pain.