We developed Figure 2 by cherry-picking the best reported values from baseline, and ignoring time point or inappropriate study design for the purpose of looking at the effect of altitude on Hgb mass.
Is there credibility hiding in Ferrari’s analysis?
I emailed him with my concerns regarding his interpretation and he graciously replied.
First, Ferrari responded with data from additional studies. One showed a Hgb mass increase “by an average of six percent in a group of 20 athletes” (Friedmann 2005); the other, an impressive “average of 8.6 percent” (Saunders 2010). He did not mention that Saunders actually had two control groups. The effect of altitude over the first control group was, yes, 8.6 percent. The effect over the second control group was a more modest 5.5 percent, or a total of 7.2 percent when the data is pooled together. Ferrari also failed to mention that Friedmann’s study focused on a sample of elite junior athletes, a point to be kept in mind for later.
Since adding studies was now fair game, I completed my own literature review. Within the short time constraints, I was able to add seven additional studies that had adequate altitude exposure (Clark 2009, Robertson 2010a, Gore 1998, Robertson 2010b, Robertson 2010c, Gough 2012, Pottgiesser 2012, Wachsmuth 2012).