Principal findings
Men and women with a broad range of ages, cancer diagnoses, disease statuses, and chemotherapy regimens participated in this study. The multimodal intervention of high intensity exercise, relaxation, body awareness training, and massage for patients undergoing chemotherapy showed broad effects. We noted significant effects on fatigue, vitality, physical functioning, role functioning, role emotional, mental health, physical component scale, and mental component scale, physical capacity (Vo2max and muscular strength), and physical activity levels, while global health status/quality of life and symptom scales did not show improvements.
The intervention was offered as a package, and it must be viewed as an entity, whereby each component has had a role in the outcomes. Our findings confirmed that both men and women benefited from training in mixed groups, and no differences between men and women were observed in the dropout rate.
The primary outcome, fatigue, was the most frequently reported symptom; 65% of the study population reported a fatigue level greater than that of the general population (mean >20) at baseline31 and 29% reported severe fatigue (mean >60).
The effect size of the improvement in fatigue (0.33) suggests a small to medium clinically important change.29 30 32 Our result differs from findings of a meta-analysis which indicated that the magnitude of effect from exercise on cancer related fatigue might be too small to be clinically meaningful (effect size=0.13, 95% CI −0.06 to 0.33).7 A Cochrane meta-analysis found the association between exercise and fatigue to be insignificant and inconclusive owing to lack of studies.9 Likewise, two recent exercise studies of moderate intensity in women with breast cancer receiving adjuvant chemotherapy found no significant improvements in fatigue.33 34
The cause of fatigue in cancer patients remains nebulous and multifactorial. Patients report fatigue as a state of physical disturbance and loss of function, with exhaustion being the lead factor in reduced physical activity. Severe fatigue results from extreme muscular de-conditioning caused by both the disease and treatment but can also be triggered by a sedentary lifestyle.35 However, only 18% of the study population had a sedentary lifestyle at baseline, which may indicate that their fatigue burden was primarily due to the disease or to the chemotherapy. The patients’ level of fatigue (mean 39.7, SD 25.8) corresponded to those obtained in other studies investigating cancer patients with the same WHO performance status and severity of disease (mean 40, SD 26).32
Although the intervention reduced the patients’ levels of fatigue after six weeks (mean 34.6, SD 24.3) the scores after intervention did not reach the level of the general population (mean 21).
Our qualitative research with participants from the pilot study showed that a reduction in fatigue could not be interpreted as an overall improvement in quality of life. However, a complete, partial, or periodic reduction in fatigue affected the patients’ daily lives.36
Consistent with recently published studies and meta-analyses on exercise interventions, including those in women receiving adjuvant therapy for breast cancer7 8 9 33 34 we found no significant improvements in global health status/quality of life (EORTC QLQ-C30), which incorporates two questions: “How would you rate your overall health during the past week?” and “How would you rate your overall quality of life during the past week?”
Courneya et al tested resistance versus aerobic exercise for the duration of the patients’ chemotherapy (17 weeks) in 242 patients with breast cancer. Neither aerobic exercise nor resistance training significantly improved cancer specific quality of life (as measured by functional assessment of cancer therapy questionnaire—anaemia).34 Mutrie et al conducted a 12 week supervised group exercise programme during chemotherapy for early stage breast cancer in 203 women, and no significant effect was seen for general quality of life (functional assessment of cancer therapy questionnaire—general).33
The failure of the intervention to significantly improve global health status/quality of life indicates that this type of short term intervention was not able to overcome the complexity of patients’ overall negatively affected situation. Being diagnosed with cancer and exposed to chemotherapy disrupts the patient’s life, affecting physiological and psychological functioning and contributing to negative effects on the global health status/quality of life.37 38 Improvements in this measure may have been too ambitious a goal in this short term clinical trial.
The intervention showed no significant effect on seven of eight somatic symptom scales in the EORTC QLQ-C30 questionnaire. This finding might because many side effects induced by chemotherapy can be prevented or treated by supportive care drugs; for example, evidence based guidelines exist for the prevention and treatment of nausea, vomiting, and diarrhoea.39
Supportive medical treatment may consequently have caused the observed floor effect where 50-70% of the study population were placed in the lowest quartiles on six of the symptom scales. Similarly we found a ceiling effect on three EORTC QLQ-C-30 functional scales.
By contrast, no such floor-ceiling effect was seen when applying the general wellbeing MOS SF-36 scale—which might be a more sensitive tool than the others for measuring effects of exercise in cancer patients—a finding confirmed in other exercise intervention studies.11 40
Significant effects of the intervention were recorded for seven of 10 subscales for general wellbeing (MOS SF-36), with small to medium effect sizes for six of the scales. The present multimodal intervention showed greater significant effects and higher mean differences on several scales (MOS SF-36) compared to a 26 week supervised aerobic exercise programme in breast cancer patients receiving less toxic chemotherapy.40 Particularly, vitality showed an effect size that was greater than medium (0.55). In existing meta-analyses regarding exercise based interventions, fatigue and quality of life are often highlighted, while measurement of vitality and its association with fatigue are not.7 8 9 In the present study an explorative general linear model analysis demonstrated that changes in fatigue were strongly affected by an increase in vitality. This finding may suggest that the multimodal intervention including a high intensity component generates vitality and thereby reduces fatigue. The patients’ perception of improved vitality is important especially during chemotherapy treatment periods.36
At baseline, the patients had a mean score of 30.5 (SD 35.2) on the role physical scale, which was below that of the general Danish population range (mean 83.1, SD 31.7).41 By comparison with the control group the intervention group showed a lesser degree of limitation by their physical status when carrying out daily activities after intervention. Overall, they are ranked at a considerably lower level than the general population. By contrast, the patients in the intervention group scored high on the physical functioning scale at baseline (mean 84.3, SD 37.2) and after the six week intervention (mean 88.2, SD 13.2), their score was similar to that of the general Danish population (mean 87.6, SD 19.4).41 This finding confirms possibly the patient group’s predisposition for doing physical activity and that the intervention group was prepared to partake in demanding activities without health related constraints. With respect to the role emotional, mental health scales, and mental component scale, the patients in the intervention group showed significant improvement but had lower scores than their age equivalents in the general population.
In summary, our results in patient rated outcomes show small to medium effect sizes across a broad spectrum of physical and emotional wellbeing scales, including vitality and self reported physical activity levels. Furthermore, we found a reduction in fatigue, which we consider to be of importance to the patients’ daily lives, even though no change was seen in the global health status/quality of life.
Objectively measured physiological outcomes also showed significant improvement in aerobic capacity and muscular strength. Studies in healthy adults and in people with cardiac and renal illnesses and with diabetes have shown that combined resistance and cardiovascular training programmes can have a range of beneficial effects such as increased physical function, aerobic capacity, and reduced muscular fatigue.42 43 44 45 46 Similarly, the results of the present study confirm that patients with cancer, even those undergoing chemotherapy, gain physiological benefits from combined resistance and cardiovascular training programmes.
According to a review of 26 studies by Galvao and Newton, the present study is the first of its kind to incorporate a high intensity design.47 The results indicate that the high intensity design is an effective training programme as both muscle strength and overall fitness improved during a short time period. Patients with evidence of disease experienced the same improvement as patients with no evidence of disease. Improvements in muscle strength and fitness in this intervention are within the same range as in the exercise interventions that included patients with lesser burden of disease post-treatment and who showed improvement in specific areas despite longer training periods. The duration and frequency of the high intensity training sessions in the present study (270 minutes per week) imply a larger training volume than in single mode exercise interventions (120-135 minutes per week).7 9 47
Improvement in the patients’ self reported vitality and physical functioning were probably attributable to the high intensity component, since a connection exists between high intensity training and vitality in healthy athletes.48
On days with high intensity exercise training, the sessions closed with low intensity relaxation training. The aim was to assist the patients to recognise and test their own physical reactions, such as dizziness, over-exertion, and cold sweat. The patients were advised to concentrate on breathing and muscle tension, and gain awareness of their physical and mental reactions. In this way the patients stabilised physically and emotionally before returning to their daily activities. These findings correspond to single intervention studies regarding patients’ perception of self control.49 On the other hand the intervention did not affect the patients’ levels of nausea, vomiting and pain suggesting non-effectiveness or simply that the patients in this study had a low level of symptoms at baseline.
Incorporating a heterogeneous group of cancer patients, each presenting different treatment related side effects, increases the need for daily pre-exercise screening by clinical nurse specialists. This has been of importance in preventing serious adverse events during high intensity programmes. Five participants were excluded from the high intensity physical training component (total of 25 times) during the study period because of leucopenia and/or increased blood pressure. Intermittent increase in heart rate and/or blood pressure were commonly observed in two or three patients weekly. In these cases, values for heart rate and blood pressure were retained after 10 minutes of recline, to meet pre-screening criteria and approval to enter the exercise room.
Five participants with breast cancer had lymphoedema at baseline; none experienced exacerbations during the intervention. One participant with a brain tumour experienced a grade 3 seizure after cardiovascular training. This participant was admitted to the hospital, recovered within 3 hours, and was discharged the same day. The participant was subsequently excluded from the intervention. We must therefore advise patients with brain tumours or brain metastases not to participate in high intensity exercise interventions. The inclusion and exclusion criteria, the daily screening procedures, the presence of the clinical nurse specialist during training, and training sphygmomanometer ensured the required level of safety. The combination of a training facility at the hospital and professional supervision was crucial and confirmed the patients’ understanding that the training programme was a supplement to medical treatment. Despite the multimodal intervention being short term (six weeks) the volume of the intervention seemed adequate.
Strengths and weaknesses
The trial had a large sample size and included male and female patients with advanced cancer and different types of diagnoses. The strengths of the trial include supervised and structured exercise, combined high and low intensity components, use of validated objective physiological measurements, validated questionnaires, intention to treat analyses, and limited dropout rate of 12.7%. All participants were undergoing chemotherapy during the study period. Limitations included adherence rate of 70.8% and a 53% recruitment rate, which are comparable with other exercise interventions including cancer patients with lesser disease burden.33 34
One weakness of the study is that while we were able to report the immediate effects of the intervention it was not possible to perform valid comparisons of the effect between the control and the intervention groups 3 months after intervention. The reason is that 59.7% of the control group patients subsequently elected to participate in the intervention following their six week participation in the study. Study allocation was not concealed, either to the patient or to the healthcare professionals, and the control group was allowed to freely increase physical activity.
Another weakness of the study is that the professionals conducting the daily exercise sessions also collected the data, which may have led to significant bias. However, research assistants who were not involved with the participants keyed in and analysed the data.
Self selection of participants in our study resulted in a sample of cancer patients who were overtly motivated to engage in group based physical activity.
Our findings suggest that population heterogeneity does not preclude use of this type of intervention. However, generalisation may be limited by the willingness of patients to allocate the necessary time to physical activity. Furthermore, all patients in the present study had a good performance status (WHO 0-1) and did not have brain or bone metastases. Our intervention may need to be modified in patients with a performance status of 2 or greater. Finally, we consider it a great challenge to motivate patients who are not interested in physical training in groups with mixed gender.
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