Heel strike running is bad because multiple lines of research over the last few decades have proved the many verifiable aspects of heel strike running that are primarily responsible for nearly all running injuries vs forefoot running.
Is Heel Striking Less Efficient Than Forefoot Running?
One way heel striking when running is less efficient than forefoot running is that it fatigues the legs faster. This is because landing heel-first when running puts more taxing mechnanical and physical stress on the muscles, soft tissues, joints and bones as compared with forefoot running.
