Exercise as it relates to Disease/Reviewing the cardiac and stress response to high intensity interval training on breast cancer survivors

What is the background to this research?
- In Australia, there is an estimated 19,807 females diagnosed with breast cancer in 2020 alone. . In addition, cardiovascular disease (CVD) includes a range of conditions that affect the heart and blood vessels. It is estimated that 1.2 million Australians have one or more heart or vascular conditions (2017-2018). Sadly, CVD remains the largest cause of death for breast cancer survivors.

- Whilst there is abundant research showing the physical and psychological benefits of physical activity, research to the specific dose of exercise is still undetermined. The aim of this pilot study was to determine the impact of exercise intensity on aerobic fitness. It was the first of its kind to measure the combination cardiovascular fitness with cardiac regulation (HRV), salivary biomarkers of stress in breast cancer survivors.

Where is the research from?
- This study was conducted at the University of Canberra, Australia. The study was published online 20 August 2020. Kellie Toohey, Kate Pumpa, Andrew McKune, Julie Cooke, Marijke Welvaert, Joseph Northey, Clare Quinlan & Stuart Semple we all contributing authors in the study. All authors involved have been part of numerous research studies in this field and are considered to have great experience and knowledge in this field of work and research.

- This study was registered through the Australian New Zealand Clinical Trials Registry and was approved by The University of Canberra Human Research Ethics Committee.There were no organisations or funding linked to this research project that may cause bias or conflict in this paper.

What kind of research was this?
- This research paper was a pilot randomized control trial (RCT). The RCT is considered to have a high level of evidence as its designed to be unbiased and help reduce the risk of systematic errors.

- Being a pilot study, the research conducted was examined on a small scale and sample size. Therefore, it can be difficult to fully examine the effectiveness of the intervention on a small population. However, the research conducted provides appropriate preparation and is a fundamental phase allowing further research on a much larger scale intervention.

What did the research involve?
- This study was a pilot 3-arm intervention which took place over 12 weeks. To be considered for the study individuals had to be:

1) Females aged 50-75 years

2) Sedentary as classified by the America College Of Sports Medicine

3) Within 2 years post cancer treatment

4) Did not take blood pressure medication

5) Did not have secondary cancers or bone metastasis

6) Ability to perform exercise sessions on a stationary cycle ergometer.

- Once each participant was randomly selected to their exercise intensity group they attended the University of Canberra laboratory 3 times per week for 12 weeks (up to 36 sessions). The testing was conducted on a Monark Cycle Ergometer. Participants in the HITT group completed 7/ 30-second intervals with a 2-minute active recovery cycle between efforts.

- Participants in the CMIT group cycled for 30 minutes at 55-65% of their maximal power and workload was adjusted. All sessions were monitored by an Accredited Exercise Scientist and participants heart rate and rate of perceived exertion (RPE) was monitored throughout the session to ensure exercise was safe and effective. There was a control group used, who undertook normal daily lifestyle for the entirety of the 12 weeks.

Study limitations

→ With a sample size of only 17 participants, it is difficult to draw meaningful conclusions of the effectiveness of the finding and results of the study

→ Eligibly of the study excluded males, despite males developing breast cancer. Therefore, results and conclusions are gender selective and further research is needed to make conclusions on the male population.

→ While participants received training on saliva collection, self-collection allows for inaccuracy and human error. Saliva collection by the Accredited Exercise Physiologist may have improved data accuracy.

→ As the intervention was conducted on the Monark Cycle Ergometer, only the lower body was targeted.

Study strengths

→ Each exercise session was closely monitored by an Accredited Exercise Physiologist to ensure safety and compliance.

→ On completion of the 12-week program, participants in the control group were offered the 12-week fully supervised intervention.

→ A maximal graded incremental cycle test was conducted to determine VO2 peak.

→ Participants were also monitored with a 12 lead electrocardiogram and blood pressure was also assessed every two minutes to further ensure that the exercise intervention was safe for the breast cancer survivors.

What were the basic results?
- On completion of the 12-week intervention results showed:

Exercise intervention:

→ The average heart rate (HR) during the exercise intervals was 150 ± 9 beats per minute (bpm) in the HITT group compared to 136 ± 16 in the CMIT group. → In both exercise groups there were no adverse events from the exercise intervention, therefor the cycle ergometer was safe and effective for breast cancer survivors.

Cardiovascular Fitness:

→ There was a significant increase in cardiovascular fitness. VO2 peak increased 19.3% in the HITT group compared to a 5.6% in the CMIT group whilst showing a -2.6 decrease in the control group.

Heart rate variability:

→ There were no significant changes from pre and post for any of the groups.

Salivary biomarkers:

→ There was no significant difference over time or between groups from pre and post testing.

What conclusions can we take from this research?
- It can be concluded from this study that when comparing dose of exercise intensities HITT and CMIT. The HITT group had a higher increase in cardiovascular fitness with a 19.3% increase in V02 peak when compared to 5.6% in the CMIT. Conclusions can be made that this increase in cardiovascular fitness may help reduce the risk of developing cardiovascular disease in the group of breast cancer survivors.

- However, authors stated that due to the small sample size caution must be taken regarding the findings and further clinical trails should be conducted on a longer and larger scale to confirm results. This conclusion aligns with other research relating to HITT physical activity interventions for participants with cancer survivors.

Practical advice
- High intensity interval training is becoming a popular exercised regime. With the busy world we all live in finding the time to exercise can be challenging, and for the majority of the population knowing type, frequency and duration of exercises can be difficult and confusing. Fitness centres such as HITT Republic and F45 focus on just that, high intensity interval training; with full body workouts lasting 30 minutes to an hour. A fitness trainer that has a Certification 4 in personal training runs classes; workouts are monitored and designed by a professional with knowledge and experienced.

- Sessions can be tailored for individual exercise levels to help improve physical fitness and overall health and wellbeing. However, individuals with any prior health conditions or concerns should visit their local general practitioner before participating in any physical activity.

Further information/resources
- If interested here is some more information.

Support groups

Breast cancer support group

The Heart foundation

Related articles

High-intensity exercise interventions in cancer survivors: a systematic review exploring the impact on health outcomes

Cognition in breast cancer survivors: A pilot study of interval and continuous exercise

Does low volume high-intensity interval training elicit superior benefits to continuous low to moderate-intensity training in cancer survivors?