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Background Exercise has been shown to decrease breast cancer risk and slow the progression of breast cancer. Physician recommendations and clinical research data most often are for gym-based exercise programs. However, the importance of exercise location on mood and stress hormones that may influence adherence to exercise has not been addressed. Methods Women first walked for an hour outdoors along a university path and then a week later, for an hour indoors on a treadmill in a typical gym environment. Pre and post outdoor and indoor exercise moods (happy, pleased, sad, frustrated, worried, angry, delighted, and joy) were assessed by a 6 point Likert questionnaire, and saliva samples were collected for analysis of cortisol, and alpha amylase (a surrogate for serum norepinephrine). Results Nineteen healthy, non-smoking, postmenopausal women (average age 58 ± 4) participated. Compared with scores after walking outdoors, walking indoors was associated with higher scores of worry (p = 0.02; mean difference 0.9; 95% CI (0.17, 1.6) and frustration (p = 0.03; mean difference 0.9; 95% CI (0.12, 1.6), and lower scores for feelings of being pleased (p = 0.03; mean difference -0.8; 95% CI: -1.7, 0.1) and delighted (p = 0.05; mean difference -0.9; 95% CI: -1.75, -0.02). Changes in salivary hormone levels did not vary significantly between the two environments. Conclusion Walking outdoors was associated with improved mood, but walking indoors was not. Improved mood may reduce breast cancer risk indirectly by promoting regular exercise. Physician recommendations for exercise should include gym and non-gym based exercise options.
Teas et al. (Mon,) studied this question.