To assess the biomechanical changes following a systematic gait retraining to modify footstrike patterns from rearfoot strike (RFS) to midfoot strike (MFS). Pre-post interventional study. All participants underwent a gait retraining program designed to modify footstrike pattern to MFS. Research laboratory. Twenty habitual RFS male runners participated. Gait evaluations were conducted before and after the training. Footstrike pattern, vertical loading rates, ankle and knee joint stiffness were compared. Participants’ footstrike angle was reduced (p < 0.001, Cohen’s d = 1.65) and knee joint stiffness was increased (p = 0.003, Cohen’s d = 0.69). No significant difference was found in the vertical loading rates (p > 0.155). Further subgroup analyses were conducted on the respondents (n = 8, 40% of participants) who exhibited MFS for over 80% of their footfalls during the post-training evaluation. Apart from the increased knee joint stiffness (p = 0.005, Cohen’s d = 1.14), respondents exhibited a significant reduction in the ankle joint stiffness (p = 0.019, Cohen’s d = 1.17) when running with MFS. Gait retraining to promote MFS was effective in reducing runners’ footstrike angle, but only 40% of participants responded to this training program. The inconsistent training effect on impact loading suggests a need to develop new training protocols in an effort to prevent running injuries. •A transition from RFS to MFS does not guarantee a reduction in impact loading.•MFS transition is coupled with an increase in knee joint stiffness.•Adopting MFS is not a “one-size-fits-all” approach in reducing running injury risk.