Exercise as it relates to Disease/The effects of high-intensity interval training compared with resistance training in prostate cancer patients

This is a critique of the research paper 'The Effects of high-intensity interval training compared with resistance training in prostate cancer patients undergoing radiotherapy: a randomized controlled trial. Prostate Cancer and Prostatic Diseases' by Elise Piraux and colleagues.

What is the background to this research?
Prostate cancer is the fifth leading cause of cancer related deaths in men worldwide, with cancer related fatigue and cancer-treatment-related-fatigue being a debilitating side-effect of the treatments and disease. Exercise appears to reduce cancer-treatment-related-fatigue, during and post-treatment. Although, the specifics surrounding cancer and treatment type require extensive investigation, as do the exercise characteristics such as type, intensity, frequency and more. Therefore, Elise Piraux and colleagues aim to investigate such questions.

The primary outcome of the study was to compare the effectiveness of Resistance Training (RES) and High-Intensity Interval Training (HIIT), compared to the control group of Usual Care (UC) on Cancer-Treatment-Related Fatigue (CTRF), in Prostate Cancer patients (PCa) undergoing Radiation Therapy (RT). The secondary outcomes assessed each interventions effects on: quality of life, insomnia, depression, daytime sleepiness, sleep quality, functional exercise capacity and executive function.

Where is the research from?
The study was conducted by researches at the Institute of Experimental and Clinical Research at UCLouvain, in Brussels, Belgium, where prostate cancer is the most prevalent cancer among men. Ethics approval was completed by the Ethics Committee of the Cliniques universitaires Saint-Luc and Université catholique de Louvain. The study was published in the journal 'Prostate Cancer and Prostatic Disease', by Nature Publishing Group.

The authors have considerable amounts of research published within cancer and/or exercise, and other related fields. Particularly Elise Piraux, who has had multiple articles published in relation to exercise interventions for cancer patients.

The funding was supported by grants from the National Fund for Scientific Research (Belgium) and the Institute of Experimental and Clinical Research at UCLouvain. The authors claim there is no conflict of interest.

What kind of research was this?
The study is a randomized controlled trial, which is considered the gold-standard for assessing the effectiveness of an intervention. It works by randomly assigning participants to a group, which minimizes the ability of participant characteristics or bias to effect outcomes. The study was 'three-armed' which refers to the three groups within the study, the study was not blinded as the outcome assessors were not blinded.

What did the research involve?
Participants that fit the inclusion criteria were randomly assigned to either the RES, HIIT or UC. using a random computer generator. Originally, 78 participants agreed to the study, 26 were assigned to UC, 27 to HIIT and 25 to RES. When the study concluded, there was 24 participants in each group. The outcomes measurements were recorded 10 days before radiotherapy treatment started and after the last fraction of radiotherapy. The interventions lasted 5-8 weeks in length.

Measurements Interventions Limitations

Although the randomized controlled trial was the best approach to establishing the effects of differing types of exercise on CTRF in PCa undergoing RT, the study does have some limitations. Firstly, the length of the study was short in relation to how long CTRF may continue post-treatment. Secondly, was the lack of quantitative measures, during the RES programming, as well as outcomes. Finally, the outcome assessors were not blinded which reduces the power that comes with double-blind studies.

What were the basic results?
Considerable differences were produced between the RES & HIIT groups, in comparison to the control UC group. Firstly, the HIIT (+0.2) & RES (-0.7) groups prevented the increases of CTRF that was seen in the UC (-5.3). They also observed differences in Functional Exercise Capacity as seen in the 6-Minute Walk Test results, where HIIT (+7.5%) & RES (+6.6%) groups improved considerably in comparison to the UC (+0.1%). They failed to observe any differences between groups in reference to other secondary outcomes such as quality of life, depressive symptoms, daytime sleepiness, insomnia and sleep quality.

The conclusions the researches drew from the study were consistent with the results that were produced. They concluded that HIIT or RES is a viable option for reducing CTRF in PCa whilst undertaking RT. They also concluded that HIIT and RES improve functional exercise capacity within the population, also consistent with the results. They then theorized that the attenuated increases in CTRF may be linked to the improvements seen in functional exercise capacity as HIIT enhances oxygen consumption abilities and RES results in neuromuscular adaptations, these claims are consistent with the literature.

What conclusions can we take from this research?
The results from this study coincide with the limited yet growing body of literature, that both strength and aerobic exercise during cancer treatment can be beneficial for reducing cancer-treatment-related-fatigue, as well as improving functional capacity. The study provides further insight into the specifics of aerobic intensity and its effects on improving functional capacity, in comparison to other studies. Particularly that HIIT appears to be a greater stimulus for improvements in CTRF, in comparison to lower-intensity, continuous aerobic exercise.

Practical advice
The study provided multiple considerations for the practical implication of exercise interventions for cancer treatment patients.
 * 1-on-1 supervision of training sessions by a trained health professional, to better improve compliance to the program. As well as ensuring proper exercise performance and avoid adverse health events.
 * The use of cardiac stress testing prior to participating in high-intensity exercise, as well as in-depth health screening. Exercise tolerance is reduced during cancer treatment, and the use of stress testing and pre-exercise screening reduces the chances of adverse health events.
 * High-Intensity-Interval-Training produces greater improvements in functional capacity in comparison to Moderate-Intensity-Continues-Training, and where possible should be implemented.

Further information/resources

 * Exercise During Cancer Treatment
 * Exercise and Cancer: Overview
 * The Effect of Physical Exercise on Cancer-related Fatigue during Cancer Treatment: a Meta-analysis of Randomised Controlled Trials