Aim: The aim of this systematic review was to investigate injury risk when running in minimalist shoes compared to running in traditional running shoes. The purpose of the study was also to identify risk factors that could increase the risk of developing a running related injury when running in minimalist shoes, compared to running in traditional running shoes.

Method: The databases PubMed, SportDiscus, ScienceDirect, CINAHL and Cochrane were searched for relevant studies. Ten studies were included in the systematic review and the quality of the studies was reviewed according to the PEDro Scale. Three out of ten studies were randomized controlled trials and seven studies were crossover trials. Five out of seven crossover trials described a randomized intervention order.

Results: General injury risk when running in minimalist shoes compared to running in traditional running shoes was evaluated in two randomized controlled trials. One study showed a significantly increased injury risk and one pilot study showed no significant results due to a small population size. Biomechanical factors related to injury risk were assessed in two randomized controlled trials and seven crossover studies, showing that there was a significant increase in forefoot pressure, vertical loading rate and Achilles tendon load when running in minimalist shoes compared to running in traditional running shoes. There was no significant difference in rearfoot pronation when comparing the two footwear conditions.

Conclusions: Moderate evidence shows that running in minimalist shoes increases the forefoot pressure compared to running in traditional running shoes and thereby increases the risk of developing metatarsal stress fractures. Limited to moderate evidence shows that running in minimalist shoes also increases the loading of the Achilles tendon, compared to running in traditional running shoes, which may increase the risk of developing chronic Achilles tendon pain. Starting to run in minimalist shoes, when accustomed to running in traditional running shoes, should be based on a gradual increase of training volume in order to avoid an increased injury risk.