Physically active women are 25 per cent less likely to get breast cancer, but certain groups are more likely to see these benefits than others — please see link.

The type of activity undertaken, at what time in life and the woman’s body mass index (BMI) will determine how protective the activity is against the disease.

Lean women who play sport or undertake other physically active things in their spare time, especially if they have been through the menopause, have the lowest risk of breast cancer.

The researchers reviewed the literature and analysed 62 studies looking at the impact of physical activity on breast cancer risk. They then examined how breast cancer risk was affected by type of activity, intensity of activity, when in life the activity was performed and other factors.

The most physically active women were least likely to get breast cancer. All types of activity reduced breast cancer risk but recreational activity reduced the risk more than physical activity undertaken as part of a job or looking after the house. Moderate and vigorous activity had equal benefits.

Women who had undertaken a lot of physical activity throughout their life had the lowest risk of breast cancer, and activity performed after the menopause had a greater effect than that performed earlier in life.

Physical activity reduced breast cancer risk in all women except the obese and had the greatest impact in lean women (BMI of less that 22kg/m2).

Women who were mothers, had no family history of breast cancer, were not white also had a reduced risk of breast cancer.

The authors said the way in which physical activity protected against breast cancer was likely to be complex and may involve effects on sex hormones, insulin-related factors, the immune system and other hormone and cellular pathways.

Contact:
Dr Christine M Friedenreich
Division of Population Health and Information,
Alberta Cancer Board.

BJSM Citation:
Walking or vitamin B for cognition in older adults with mild cognitive impairment? A randomized controlled trial.

Authors: Jannique G.Z. van Uffelen, Marijke J.M. Chinapaw, Willem van Mechelen, and Marijke Hopman-Rock
Links to:
ABSTRACT
ARTICLE

Although this study found that exercise improves some aspects of cognitive performance, it also confirmed a recent meta-analysis in concluding that that folic acid supplementation does not significantly benefit cognition. A recent article by our group suggested that much of the relationship between folate levels and cognition may be attributed to exercise because exercise is known to raise folate levels. The current article further reinforces the need for research investigating the interaction of exercise, folate, and cognitive performance.

Balk EM, Raman G, Tatsioni A, Chung M, Lau J, Rosenberg IH. Vitamin B6, B12, and folic acid supplementation and cognitive function: a systematic review of randomized trials. Arch Intern Med 2007; 167(1): 21-30.

Middleton LE, Kirkland SA, Maxwell CJ, Hogan DB, Rockwood K. Exercise: a potential contributing factor to the relationship between folate and dementia. J Am Geriatr Soc 2007; 55(7): 1095-8.

Take a look at this interesting response by Bradley Elliot, Centre de recherche de l’Hôpital Laval, Québec, Canada to Paul Joseph Boyle’s paper “Does occupational success influence longevity among England test cricketers?”

Sir,
I read the recent article by Paul Boyle (Boyle 2008) regarding the longevity of English test cricketers with interest. In this paper the authors linked length of international cricket career (’success’) with lifespan, suggesting that a successful life lead to a longer life. The hypothesis that quality of life grants one a physiological advantage and therefore increases length of life is well accepted in the medical field and its mechanisms deserve closer examination.

However, I feel that the author has potentially overreached with this conclusion by dismissing the effect of physical activity on lifespan. The author states that the increased levels of physical fitness we would expect in world class athletes are unlikely to affect lifespan because “cricket is not a sport which requires physical strength”. In this conclusion the author has incorrectly regarded fitness as musculoskeletal strength alone, ignoring the important aerobic component. Cricket is primarily an aerobic sport, and the fitness of its players is often underestimated (Noakes and Durandt 2000). Several studies in both animals and humans have demonstrated a link between aerobic activity and lifespan.
Rats subjected to only 10 minutes walking a day live 25% longer than sedentary littermates (Retzlaff et al. 1966). The classic London busmen study (Heady et al. 1956) and several others (reviewed by Warburton et al. 2006) all demonstrated that people who worked in physically active positions lived significantly longer then workmates who had more sedentary positions.

It is reasonable to assume that those who were honored to represent their country for longer had a higher level of physical activity for a longer period of time than those who did not, therefore likely having an effect on longevity.

Bradley Elliott,
Centre de recherche de l’Hôpital Laval, Québec, Canada

Boyle, P. J. (2008). “Does occupational success influence longevity among England test cricketers?” Br J Sports Med: bjsm.2007.041566.

Heady, J. A., J. N. Morris and P. A. Raffle (1956). “Physique of London busmen; epidemiology of uniforms.” Lancet 271(6942): 569-70.

Noakes, T. D. and J. J. Durandt (2000). “Physiological requirements of cricket.” J Sports Sci 18(12): 919-29.

Retzlaff, E., J. Fontaine and W. Furuta (1966). “Effect of daily exercise on life-span of albino rats.” Geriatrics 21(3): 171-7.

Warburton, D. E., C. W. Nicol and S. S. Bredin (2006). “Health benefits of physical activity: the evidence.” Cmaj 174(6): 801-9.