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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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INTENSITY AND TIMING IN LIFE OF RECREATIONAL PHYSICAL ACTIVITY IN RELATION TO BREAST CANCER RISK AMONG PRE- AND POSTMENOPAUSAL WOMEN |
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Joanna Kruk  |
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Institute of Physical Education, University of Szczecin, Szczecin, Poland |
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© Journal of Sports Science and Medicine (2010) 9, 311 - 319 |
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| ABSTRACT | |||
| Regular recreational physical activity has been found to be associated
with a decrease in breast cancer risk in women in the majority of epidemiologic
studies, but research findings are inconsistent regarding the intensity
of activity and timing in life. To address these issues the relations of
moderate and vigorous intensity recreational physical activity during ages
14-20, 21-34, 35-50, and over age 50 years to pre- and postmenopausal breast
cancer risk were examined. A case-control study of 858 women, with histological
confirmation of invasive breast cancer, and 1085 controls, free of any cancer
diagnosis, all subjects aged 28-79 years was conducted in the Region of
Western Pomerania (Poland). Physical activity was assessed using a self-administered
questionnaire with questions on type of activity, duration, frequency, and
intensity for each type of activity. Odds ratios (OR) and 95% confidence
intervals (CI) of breast cancer associated with physical activity were calculated
using unconditional logistic regression. Vigorous physical activity at ages
14-20 and 21-34 years lowered breast cancer risk by at least 35% in premenopausal
women and by at least 51% in postmenopausal women for the highest versus
lowest quartiles of the activity. The risk was also reduced in postmenopausal
women who reported on average more than 1.74 hours per week of vigorous
intensity recreational activity in ages >50 years (OR = 0.58; 95%CI =
0.27-0.97; P for trend = 0.013). For moderate activity the relationships
remained statistically significant only in postmenopausal women active during
ages 14- 20 years. The results indicate also a plausible risk reduction
among premeno-pausal women. These results support the hypothesis that recrea-tional
activity, particularly done early in life, is associated with a decrease
in the invasive breast cancer risk in postmenopausal women. Among premenopausal
women, only vigorous forms of activity may significantly decrease the risk.
Key words: Exercise, breast cancer, case-control study, prevention. |
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