Is Strenuous Jogging Bad for You?
“Too much Jogging as bad as no jogging at all” – BBC
“Too much jogging is just as bad as doing none at all” – Daily Mail
“Fast Running is as deadly as sitting on couch” – Daily Telegraph
What is going on? Were you frightened to go running last week after reading these scary headlines? What is the truth about the Danish study which purports to underlay this sensationalism?
In fact the Danish cardiological study on which the journalists based their stories was far less conclusive than claimed. The researchers grouped their 1,500 volunteers into, sedentary, light joggers, moderate joggers and strenuous joggers then again into subgroups. After following their subjects for two years they concluded that light to moderate jogging could be associated with living longer compared with being sedentary but that strenuous jogging might not be. (Note the qualifiers, might and could.)
A major limitation of the study was that once joggers were split into groups by duration, frequency and pace some of these groups were too small to be statistically significant i.e. occurring by chance. This was particularly the case in the most active jogging categories. (More often and higher pace) This reduces the ability of the analysis to detect differences between these smaller groups and the sedentary group. For example there were only 36 people who were classed as “strenuous” joggers and only 2 of these people died. The statisticians amongst you will spot straight away that with these small numbers we cannot say with certainty that there is definitely no difference between people in the most active jogging categories and the people who are sedentary.
The study was also flawed in that jogging intensity was only assessed once in the study and that death was the only outcome measured. There is no mention of quality of life, general fitness or the absence of illness in any of the groups.
Overall the study does not contradict the current physical activity recommendations of the NHS and the issue of people not doing enough exercise is more likely to be a concern than people over-exercising. What I find pernicious in news stories like this is that it gives false excuses to coach potatoes to continue to do nothing.
My advice? Keep on running but don’t forget to enjoy it!
12. 02. 2015