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EXERCISE FOR THE PRIMARY PREVENTION OF BREAST CANCER AND OSTEOPOROSIS IN POSTMENOPAUSAL WOMEN WITH OVERWEIGHT OR OBESITY
Autor/aGonzalo Encabo, Paola
DepartamentoBiología de Sistemas
Director/aGarcía Honduvilla, Natalio Antonio
Codirectores/asValadés Cerrato, David; Pérez López, Alberto
Fecha de defensa03/06/2021
CalificaciónSobresaliente Cum Laude
ProgramaCiencias de la Salud (RD 99/2011)
Mención internacionalSi
ResumenMenopause is related to several endocrine changes that are associated to increases in fat mass and reductions in bone mineral density, thus, increasing the risk of obesity and osteoporosis in postmenopausal women. Obesity during menopause increases the risk of multiple diseases, particularly postmenopausal breast cancer risk. However, regular exercise participation can reduce the risk of fat mass gains following menopause and, ultimately, prevent these chronic diseases. Given the importance of exercise as a primary prevention strategy of multiple diseases in postmenopausal women, the hypothesis of the present thesis was that different exercise parameters (e.g., volume and type) would improve intermediate breast cancer markers and osteoporosis risk in postmenopausal women with overweight or obesity, after an exercise intervention and after a follow-up period. Four studies were conducted to test this hypothesis according to the following objectives: To examine the effects of a time-matched endurance versus concurrent training (endurance + resistance training) on circulating sex hormones levels and body composition in postmenopausal women (Study 1). To compare the dose-response effects of prescribed aerobic exercise volume on adiposity outcomes (Study 2). To explore the associations between breast cancer-related biomarkers and weight regain following exercise-induced weight loss in postmenopausal women (Study 3). And lastly, to examine the effects of different exercise volumes on bone mineral density and content in previously inactive, postmenopausal women during a 12-month intervention and one year after intervention completion (Study 4). In Study 1, thirty-five postmenopausal women with obesity were recruited and randomized to a 12-week endurance training intervention (N=10), concurrent training (N=13) or to a control group (N=12). Body composition and sex hormones were measured before and after the intervention. In Study 2 data from the Alberta Physical Activity and Breast Cancer Prevention (ALPHA) Trial and Breast Cancer and Exercise Trial in Alberta (BETA) were pooled for this analysis (N=720). These were 12-month randomised controlled trials, in which participants were randomised to 225 minutes/week of aerobic exercise versus usual inactive lifestyle (ALPHA Trial), or 150 minutes/week versus 300 minutes/week (high-volume) (BETA). Body composition was measure using DXA scans and computed tomography. In Study 3, from the 400 participants included in BETA, 214 lost weight during the intervention, and had body composition and blood sample data during the follow-up and were included in these analyses. For Study 4, data from the BETA trial was used to assess total bone mineral density (g/cm2) and bone mineral content (g), with measurements taken at baseline, 12-months (end of the intervention) and 24-months (follow-up) using whole-body dual-energy X-ray absorptiometry. Based on results from these four papers, it was concluded that exercise type and exercise volume are important components of exercise prescription for reducing osteoporosis risk, via influences on bone mineral density, breast cancer risk, via influences on adiposity and sex hormones reductions, in postmenopausal women with overweight and obesity. Moreover, there is a need to maintain adiposity changes to preserve exercise-induced reductions in breast-cancer related biomarkers after a follow-up period.