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Here’s an interesting graph from a new paper from the Cooper Institute, the famous fitness institute founded by Kenneth Cooper, the “inventor” of aerobics:
The paper appears in this month’s issue of Medicine & Science in Sports & Exercise, and it shows the results of 52,785 fitness tests performed on men at the Cooper Institute between 1970 and 2009. Each patient appears only once in the data, so it’s not a longitudinal study of how individuals got more or less fit; it’s a cross-sectional study showing how the initial fitness of patients at the institute has changed over the years. The trend is pretty straightforward: a big jump from the 1970s to the 1980s, then levelling off to the 1990s, then a slight decline into the most recent decade.
So… at first glance, I found this data pretty surprising. My naive guess would have been that fitness (as represented in this graph by VO2max determined in an incremental treadmill test) would have declined steadily from the 1970s to the present. After all, we’re always hearing about how society has never been less fit. Instead, it seems that we’re fitter than we were 30 years ago, and other data in the paper suggests that we’re more active too. So does this mean that our current health woes have nothing to do with physical activity level? After all, the data also shows that average weight in the subjects has increased by 8 kg since 1970, while height has stayed the same. So we’re more active, but fatter — a pretty good indicator that diet, rather than exercise, is driving the rise in obesity.
Of course, there are a few caveats. For one thing:
Cooper Clinic patients are self-referred or referred by their employers and are primarily healthy college educated middle to upper income non- Hispanic whites who have access to medical care.
So there’s really no way of knowing whether the average patient who decides to go to the Cooper Clinic is comparable to the average patient from the 1970s. It could be, for example, that the clinic’s clientele has changed as it became famous, so that it now attracts people who are already a bit more serious about fitness. But that’s just speculation. The data may well be a fair representation of societal trends — and if so, I need to revise some of my assumptions.