text_1: To reverse damage of sitting, take a brisk, hour-long walk
text_2: This story reports on a large meta-analysis of observational studies looking at the association between sedentary behavior (sitting and TV-watching), exercise, and risk of dying prematurely. Its main take-home message is “it takes about 60 to 75 minutes of ‘moderate intensity’ exercise to undo the damage of sitting for at least eight hours a day.” Although that’s a faithful account of how the study researchers frame their results, we think it’s likely to leave readers with a misleading impression. Despite what the researchers may claim, this type of study can’t prove that exercise can “undo the damage of sitting” — all it can do is show associations between these behaviors and risk of death. There are many factors, other than exercise and sedentary behavior, that affect one’s risk of death (e.g. diet, illnesses, socioeconomic factors), and the story didn’t explain that researchers can’t account for all of those factors in a study like this. Suggesting that exercise “reverses” the damage of sitting implies a certainty to the study’s conclusions that simply doesn’t exist. Every day, readers are bombarded with health news messages from observational studies such as this one relating to diet, exercise, and other lifestyle issues. Because this type of research is not definitive, it is liable to be contradicted by the next study that comes along, which in turn generates a new set of headlines that is in conflict with what readers just heard from the last study. This generates confusion among the public and mistrust of both scientists and journalists who can’t seem to get their stories straight. We offer tips for reporting on observational studies in our toolkit.