Mortality After Changes in Leisure Time Physical Activity

An article was recently published in the British Medical Journal (BMJ 2009;338;b688) entitled "Total mortality after changes in leisure time physical activity in 50 year old men: 35 year follow-up of population based cohort," by Liisa Byberg and co-authors. The objective of the study was to examine how change in level of physical activity after middle age influences mortality and to compare it with the effect of smoking cessation. It was a population based study performed in Uppsala, Sweden with followup over a period of 35 years on 2205 men aged 50 in 1970-1973 who were re-examined at ages 60, 70, 77, and 82 years. The main outcome measure was total (all cause) mortality.

The results were remarkable, namely, that the absolute mortality rate was 27.1, 23.6, and 18.4 per 1000 person years in the groups with low, medium, and high physical activity, respectively. It is very interesting to note that men who increased their physical activity level between the ages of 50 and 60 continued to have a higher mortality rate during the first five years of follow-up. After 10 years of follow-up, their increased physical activity was associated with reduced mortality to the level of men with unchanged high physical activity. So, it appears that it takes time for the physical activity to yield a benefit, which makes sense. Remarkably, the benefits of exercise are as dramatic as those of smoking cessation.

For the purposes of this study, low physical activity was reading, watching television, attending the cinema, or other sedentary activity. Medium activity was walking or cycling for pleasure. High activity was active recreational sports or heavy gardening at least 3 hours per week, hard physical training, or competitive sports.

This is "good stuff," and confirms what one might expect - namely, that vigorous physical activity is, in the main, good for one's health. The precise physiological reasons for this were not elucidated in this study, which did not find any strong link to blood pressure reduction, cholesterol level reduction, etc. However, the authors suggest possible cause-and-effect relationships, such as beneficial adaptations in hormonal and inflammatory responses, organ system (e.g., muscles, nervous system, gut) improvements and efficiencies, and quality of life/mental health.

The implications for lovers of the outdoors is to keep up the good work. If exercise is indeed beneficial, unless one wishes to spend more time at the gym, there are myriad opportunities to achieve health and fitness in the outdoors.

Join me from January 24 to February 2, 2010 for an exciting dive and wilderness medicine CME adventure aboard the Nautilus Explorer to Socorro Island, Mexico to benefit the Wilderness Medical Society.

Tags: leisure time, exercise, physical activity, wilderness medicine, outdoor medicine, healthline