Malisoux et al. 2016, heel-to-toe drop and injury risk RCT

American Journal of Sports Medicine randomised controlled trial (553 leisure-time runners, six-month follow-up) comparing standard cushioned running shoes with heel-to-toe drops of 10 mm, 6 mm and 0 mm. Overall injury risk was not modified by drop. A frequency interaction emerged: lower-drop shoes were associated with higher injury risk in regular runners but lower risk in occasional runners. Level 1 evidence.