Exercise can extend your life by as much as five years

Janssen and his team used data from the National Health and Nutrition Examination Survey, the National Health Interview Study mortality linkage, and U.S. Life Tables to estimate and compare the life expectancy at each age for adults who were inactive, somewhat-active and active. "Active" was defined as doing at least 150 minutes of moderate activity per week.

They found that men at age 20 were estimated to gain as much as 2.4 years of life from moderate activity. Women at age 20 gained about 3 additional years from engaging in moderate activity. The biggest benefit from physical activity was seen in non-Hispanic black women, who gained as many as 5.5 potential years of life.

Janssen hopes the positive message of the study can help health officials better relay the importance of exercise to the public.

"Research has shown that the health messages that have the greatest effect on changing people's behaviors need to be easy to understand, specific to the individual, and be phrased in a gained-framed and positive manner," he explained.

"The messages on longevity gains associated with physical activity that were developed in this paper meet all three of those characteristics," Janssen added. "That is, people will understand what it means if you tell them they will live 2½ years longer if they become active."

Sara Bleich, Ph.D., assistant professor of Health Policy at the Johns Hopkins Bloomberg School of Public Health, said presenting the issue as "years of life gained" versus "years of life loss" raises the classic issue of the carrot or the stick, that is, when it comes to behavior change, do people prefer to be rewarded or penalized?

"For healthy behavior changes such as dieting or smoking, rewards have been shown to effectively motivate behavior change," she continued. "From the current research, it is unclear whether rewards or penalties are more effective at motivating behavior change, but it is clear that rewards do work."