In response to “What factors are associated with physical activity in older people, assessed objectively by accelerometry?” (abstract, full article):

We have read with interest the recently reported accelerometer study of physical activity in community-living seniors in Oxfordshire (1).

Subjects were observed for 7 days, apparently in the winter or the spring, although the only clue to the important question of season is that invitations were sent out over a 20-week period, beginning in September of 2006. In discussing their data, the authors claim (p. 446) “This is the first moderately sized population-based study of older people published to date with objective PA measures and a broad range of health, psychological and anthropometric variables.”

In fact, a much more extensive community study of seniors aged 65-99 years has been conducted previously, in the Japanese community of Nakanojo. Many of the key findings from the Nakanojo Study have been published, and are summarized in a recent review (2). The Japanese subjects were monitored 24 hours per day for an entire year, thus avoiding problems from seasonal variations in physical activity (3-6). Perhaps in part because seasonal effects are quite large in this age group, the average step counts over the whole year were somewhat higher than the 6443 steps/day reported by Harris et al. (1), particularly in the male subjects. It would be interesting to have for comparison British data that also covers an entire year. Like Harris et al. (1), we found associations of step counts with age, sex, body build, physical, metabolic and psychological health among other environmental, geographic and psycho- social variables, and our data support the view that in Asia, as in Europe, many seniors are currently taking substantially less than the recommended daily dose of physical activity.

Yukitoshi Aoyagi and Roy J. Shephard, Researchers, Tokyo Metropolitan Institute of Gerontology, Japan.

REFERENCES

1. Harris TJ, Owen CG, Victor CR, et al. What factors are associated with physical activity in older people, assessed objectively by accelerometry?  Br J Sports Med 2009; 43: 442-450.

2. Aoyagi Y, Shephard RJ. Steps per day. The road to senior health?
Sports Med 2009; 39: 423-438.

3. Togo F, Watanabe E, Park H, et al. Meteorology and the physical activity of the elderly: the Nakanojo Study. Int J Biometeorol 2005; 50:
83-89.

4. Togo F, Watanabe E, Park H, et al. How many days of pedometer use predict the annual activity of the elderly reliably? Med Sci Sports Exerc 2008; 40: 1058-1064.

5. Yasunaga A, Togo F, Watanabe E, et al. Sex, age, season, and habitual physical activity of older Japanese: the Nakanojo Study. J Aging Phys Act 2008; 16: 3-13.

6. Shephard RJ, Aoyagi Y. Seasonal variations in physical activity and implications for human health. Eur J Appl Physiol 2009; in press. doi:
10.1007/s00421-009-1127-1.