Table 2 Eligibility criteria

Inclusion criteria:

 • studies that evaluated the effects of flat insoles constructed from different materials on plantar pressures;

 • studies published in English;

 • studies that compared to a control (shoe alone) condition;

 • studies that used ‘in-shoe’ testing apparatus.

Exclusion criteria:

 • studies conducted on animals (non-humans);

 • studies that evaluated cadavers;

 • studies conducted on children (aged under 18 years);

 • studies that evaluated the effects of taping, padding, splinting, bracing, casting, contoured foot orthoses or insoles, or orthopaedic devices defined as other than flat foot orthoses or insoles;

 • studies of activities other than walking;

 • studies where participants had systemic, neurological or inflammatory arthritic pathologies such as diabetes mellitus, cerebrovascular accident, Parkinson’s disease, and rheumatoid arthritis;

 • studies that were not peer-reviewed, scholarly publications of experimental or quasi-experimental research.