Watching TV for an average of six hours a day could shorten the viewer’s life expectancy by almost five years, indicates research published online in the British Journal of Sports Medicine. The impact rivals that of other well known behavioural risk factors, such as smoking and lack of exercise. Other research has shown that lifelong smoking is associated with the shortening of life expectancy by more than 4 years after the age of 50, with the average loss of life from one cigarette calculated to be 11 minutes – equivalent to half an hour of TV watching.
A study published Online First by The Lancet shows that just 15 minutes of physical activity per day reduces a person’s risk of death by 14% and increases life expectancy by 3 years compared with inactive people. The Article is by Dr Chi-Pang Wen, National Health Research Institutes, Taiwan, and China Medical University Hospital, and Dr Jackson Pui Man Wai, National Taiwan Sport University, and colleagues.
On the basis of self-reported weekly exercise, participants were placed into one of five categories of exercise volumes: inactive, or low, medium, high, or very high activity. The authors calculated hazard ratios (HR) for mortality risks for every group compared with the inactive group, and calculated life expectancy for every group.
Compared with individuals in the inactive group, those in the low-volume activity group, who exercised for an average of 92 min per week (about 15 min a day) had a 14% reduced risk of all-cause mortality, a 10% reduced risk of all-cancer mortality, and on average a 3 year longer life expectancy. Every additional 15 min of daily exercise beyond the minimum amount of 15 min a day further reduced all-cause mortality by 4% and all-cancer mortality by 1%. These benefits were applicable to all age groups and both sexes, and to those with cardiovascular disease risks. Individuals who were inactive had a 17% increased risk of mortality compared with individuals in the low-volume group.