One of the main criticisms of studies that try to compare midfoot (and/or forefoot – the two categories are lumped together in the study, and I'll do the same for the rest of this post) strikes with rearfoot strikes is that they often involve asking people from one category to force themselves to run in an unfamiliar way for a short period of time, then draw conclusions based on this limited sample. Alternately, other studies assemble different groups of midfoot and rearfoot strikers, but with such diverse characteristics that it's hard to draw any conclusions from the comparison. The strength of the new Spanish study is in addressing these concerns: they assembled two very homogeneous groups of sub-elite distance runners, with 10 midfoot strikers and 10 rearfoot strikers. The groups were very closely matched in age, running experience, training volume, BMI, VO2max, HRmax, and fitness, with average half-marathon bests of 1:10:59 and 1:10:21 (all runners in both groups had run between 1:06 and 1:14, and all had completed a half-marathon in the six weeks prior to the study).