Intense Exercise in the Quality of Life of Breast Cancer Survivors: A Meta-analysis

The treatment of breast cancer (BC) leaves emotional and functional sequels affecting the quality of life (QOL) of the survivors. We aim to investigate, intense exercises in the rehabilitation of BC survivors. Using the systematic search model in the PubMed databases; Lilacs Bireme and Scielo. Meta-Analysis used the Meta package implemented in software R (version 3.3.2) p < 0.05. We selected 29 articles, and after reading in the integra we excluded 27 texts being included in the meta-analysis only 2. In the QOL, the heterogeneity in the emotional function showed a difference of 75%, in the social function 36% and in the physics 32%. Using intense exercises in BC survivors during rehabilitation improves overall QOL, muscle structure, and preserves functional capacity.


Introduction
Breast cancer (BC) is a malignant neoplasm regarded as a chronic degenerative disease that mainly affects women [1]. In Brazil, it is the first cause of death among this population. The risk of developing this cancer throughout life is one in seventeen Brazilian women, and two thirds of the cases occur after menopause and 15% in women before 40 years of age. It is noteworthy that at least one third of new cases of cancer occurring in the world, annually, could be avoided [2].
The impact of the diagnosis of this disease and the treatment process generate serious consequences that may be temporary or permanent in woman's lives [3]. For every process whether it is conservative or not (with surgical procedure) can cause important decreases in self-esteem, limitations of the physical capacity of the upper limb due to the presence of lymphedema, and also the change of the tactile sensation of the sinus after Its reconstruction that can affect the femininity and performance of motherhood [4].
On the other hand, studies indicate that in a clinical routine it is possible to aggregate and develop the regular practice of physical exercises, especially in order to prevent and mitigate the symptoms resulting from the treatment. As a consequence, there are also improvements in cardiorespiratory and functional capacity [4][5][6]. According to the World cancer Research Fund [5], the regular practice of physical exercise is considered a protective factor for the postmenopausal BC, however, despite the efficacy of the practice of physical exercise in the treatment of breast cancer to be widely known yet there is no a consensus on the exact prescription of the type, intensity, duration and method most appropriate for women who experience the treatment of BC.
The literature is still inconsistent, although there is strong evidence on the important health contributions brought by a physically active body [8]. This is probably due to the fact that both the complexity of the disease and the enormous heterogeneity of existing training exercises and protocols, which end up hindering such recommendations [9]. In general, the literature argues that during the recovery process, which occurs after the treatment of chemotherapy, radiotherapy and post mastectomy surgery, physical exercise acts by increasing the adaptability of the muscular and cardiac functional capacity of women undergoing these processes [10]. What is extremely important since a sedentary lifestyle at this stage can cause an additional decline in functional capacity and should be avoided as much as possible [11,12].
The recommendation most commonly used in the prescription of exercises in the posttreatment phase, are interventions of resistance exercises with low loads, especially in case of lymphedema after cancer and with mild intensities, performing only movements as a function that is closer to everyday life; Initially should prioritize exercises that require less strength or involvement of the pectoral muscles and gradually increase both the frequency and complexity according to the carrying capacity of these women [13,14].
However, the use of exercises with higher loads and intensities has also shown effective results; The exercises promote improvement of body composition, endurance, muscular strength, flexibility and improvement of cardiorespiratory fitness .
In view of the above, this article aimed to produce a bibliographic study, of a systematic review with meta-analysis, that would bring together the main literary data that were produced up to the present day on the benefits of the use of high Load or high intensity in women surviving breast cancer, in order to identify the positive effects of this type of intervention.

RESEARCH AND STRATEGY
This systematic review with meta-analysis is registered at the International Prospective In the investigation process, the advanced search tool was used during the searches and when available in the database, the filter for clinical trials was used. The following

Results
In the first selection, data were analyzed by means of the titles and abstracts and through this process 26 articles from the PubMed database were selected. And in the second selection that also followed the procedure to analyze the titles and summaries of the articles contained in the data, the search resulted in only three articles from the database Bireme, totaling 29 articles selected for the full reading.
It is noteworthy that in the databases: Scielo and Lilacs The results of the searches were equivalent to zero academic texts. Proceeding with the procedures, after the selection and reading in full of the 29 academic studies, 27 articles were excluded, thus remaining only two texts that were included in this meta-analysis, as described in graphic details shown in figure 3 (Flowchart of identification and selection of articles for systematic review).
It is important to report that in relation to the results of the permitted access articles there were no review studies of literature reviews of any specific modality (systematic, integrative, etc.), and that the discarded papers, 19 articles did not conform With the theme proposed by this research (in the case of high load and intensity exercises). Three were excluded from this research because of their study design that did not corroborate the inclusion criteria described earlier in the methodology of this review, two more were not used because they did interventions with exercises in parallel with the use of pharmacological methods, and finally the last three among the 27 excluded studies, were dispensed by the fact that they did not present the samples composed exclusively by individuals who were affected by breast cancer (BC).
Thus, only two literary data were left that fit the criteria proposed by the theme and methodology of the present study. The studies used in this study had in common the evaluation data of essential components of quality of life in survivors of BC who performed high-intensity physical exercises, such data underwent a statistical procedure of Metaanalysis and were exposed in detail in  Table 1 shows that in the first study we used an exercise protocol that made use of high loads between 75% and 85% of one repetition maximum (1 RM) versus low load exercises between 55% and 65% of 1 RM, for women survivors of Breast cancer (BC) with clinical diagnosis of Secondary lymphedema. We know that women who have undergone a surgical intervention due to BC, tend to report the increase of symptoms including pain, heaviness, numbness and stiffness in the upper limb [16].
In addition, there is a considerable loss of muscle strength in the affected arm [17,18]. And with the loss of strength come the limitations of biomechanical functions [19,20]. The physical exercise in particular the training with external loads, is one of the most used strategies for the improvement of the biomechanical function through the increase or restructuring of the muscular strength [20,21].
The treatment through training with external loads also contributes to the increase of lymphatic clearance through the natural effect of [22,23] muscle pump. It is observed that the exercise performed with the lifting of higher loads between 70% and 95% of 1RM, bring additional advantages in relation to the percentages of lower loads, the literature states that there is a relationship between the load response of the exercise of Strength and magnitude of gains in muscle structure and function [24,25].
The results of the first study in table 1 corroborated the physical evolution of CM survivors, considering that the group that performed the intervention between 75% and 85% of 1 RM, also presented higher gains in relation to the increase in the functionality of the force and muscular resistance when compared to the control group. It is noteworthy that the same occurred with the group that performed the interventions between 55% and 65% of 1 RM and that no differences were found between the groups, in relation to the level of the swelling of the lymphedema and the other symptoms. In addition, a significant improvement in quality of life (QOL) was identified in the women studied.
Therefore, the results indicate that women surviving BC, (provided they are accompanied by a qualified and appropriate professional to perform interventions with physical exercises), even if they are lymphedema secondary to BC, can make the use Low loads, and high in interventions for physical improvement and QOL. It is known that exercise is a beneficial and positive therapy for this population, whether it is applied during and or after the course of the disease, resulting in expressive clinically proven improvements, regardless of the intensity or type of exercise used in Intervention [26,27].
Another reason to use the practice of exercises in treatment procedures or oncologic prevention is that cancer cells feed on energy reserves, which are stored in the human body in the form of adipose tissue [28]. For this reason the adipose body mass potentializes the risks for the acquisition of various types of cancer, making it necessary to include regular physical exercise during the treatment process with the objective of decreasing and/or preventing the increase in the levels of Adiposity [29].
One of the training methods, which has been highlighted is the high intensity interval training known as HIIT (High intensity Interval Training), which in addition to showing good results in relation to its efficiency for body slimming [30], has become another tool to be used in the treatment of surviving women of BC.
In the results of the second article also contained in table 1, we observe the use of a multimodal rehabilitation protocol, which made use of HIIT with intensity at 95% of the peak of the maximal heart rate and compared with the exercises of low to moderate intensity.
The group that performed the intervention with HIIT obtained body fat reduction, while in the low to moderate intensity group there were no changes in relation to this variable.
Similar results are found in the study by Devin [31], who underwent intervention of four weeks of high intensity exercise and identified improvements in both cardiorespiratory fitness and body composition of the studied sample, which was Comprised of women surviving cancer. It is important to emphasize that women who experience the treatment of breast cancer present a great decline in QOL, especially in aspects that involve social and emotional life, which ends up affecting their functions of autonomy and biomechanics. Thus, general health impairment is observed, reducing the cardiorespiratory, metabolic, fitness and increase of body fat, being these risk factors predictors of the disease and quite detrimental to the success of the treatment [27,28].
Being physically active, it brings several contributions to the QOL and acts in parallel in the prevention of various types of diseases [8]. Moreover, they have a positive influence on mood, improves body image and self-esteem, acting in this way in the reduction of the sequels and the physical and emotional symptoms experienced during the treatment of Cancer [32].

Conclusion
The studies used in this meta-analysis, pointed out that it is so safe and effective to use high intensity exercises as moderate exercises in women survivors of breast cancer, and that in addition to ampliform the general quality of life the methods of high Intensity can also be used by health professionals to optimize the time of interventions, bringing a quality of benefits to improve resistance, muscle structure, maintenance of functionality, and contribute to a reduction Significant body fat, and in relation to physical, emotional and social functions related to quality of life, the data showed that there was no statistical difference between the use of mild to moderate and high intensities.
Declarations FUNDING Nothing to declare.

CONFLICTS OF INTEREST
All authors declare that there are no conflicts of interest.

COMPLIANCE WITH ETHICAL STANDARDS
The present study followed the international ethical principles for the production of a systematic review with meta-analysis, and was developed based on the PRISMA checklist  ii) Low to moderate intensity exercises (n = 14).
Group monitoring: heart rate was

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