Seasonal cold and circadian changes in blood pressure and physical activity in young and elderly people

Aim: to test the hypothesis that there is no association between seasonal c old and the circadian responses of blood pressure, deep-body temperature an d physical activity in healthy young and elderly men. Methods: 25 healthy elderly (aged 70-82 years) and 21 young volunteers (age d 20-30 years) participated in a 3-year prospective cross-seasonal study. Results: ambulatory day-time blood pressures in the older men were higher i n the winter than in the summer and higher in both seasons than in the youn g people. The seasonally related differences were associated with lower out door and indoor temperatures, lower body temperature and higher activity le vels in the elderly group in the winter. The older but not the younger grou p had higher blood pressure and levels of physical activity at certain time s of the day in the winter compared with the summer. Conclusion: time-of-day winter increases in blood pressure in older people may be related to increased activity as well as to levels of ambient temper ature. Although it is generally advantageous for older people to he physica lly active in order to prevent circulators disease, there may be a rational e for advising that that they should avoid intense activity at certain time s of the day, especially in the winter.