Comprehensive biomechanical characterization of feet in USMA cadets: Comparison across race, gender, arch flexibility, and foot types.

This was a cross-sectional description of healthy incoming cadets; it did not measure injuries, pain, or response to treatment. The sample was selected: cadets who completed rigorous entrance physical tests, so findings may apply only to physically active college-age people. Data were incomplete for many participants: 34 were excluded from all analysis, 15 were missing race, 9 were missing gender, and 9 were missing body weight. Native American (6) and other race/ethnicity categories (21) were excluded from race comparisons because of small sample size. Foot type was classified from standing arch height index cutoffs, not from clinical goniometric measures of forefoot to rearfoot, subtalar alignment, hindfoot alignment, or compensation. Arch flexibility categories were made by quintiles, so flexible and stiff are relative groups within this cohort, not fixed clinical thresholds. The study did not measure forefoot width or joint subluxation, so it cannot explain why planus feet did not always elongate as expected.

Howard Hillstrom and Jinsup Song are consultants to JakTool LLC, the company that makes the Arch Height Index Measurement System used in the study; all other authors declared no conflicts.

Do not use these foot-type differences to predict injury risk. The study measured healthy cadets and did not link foot structure, function, or flexibility to injuries, so the differences are descriptive, not diagnostic or treatment evidence.