The aim of this systematic review was to evaluate the literature pertaining to the effect of foot posture, foot orthoses and footwear on lower limb muscle activity during walking and running. A database search of Medline, CINAHL, Embase and SPORTDiscus without language restrictions revealed 504 citations for title and abstract review. Three articles were translated to English and a final 46 articles underwent a two-tiered quality assessment. First, all articles were scored for their reporting of electromyographic methodology using a set of standards adopted by the International Society of Electrophysiology and Kinesiology. Thirty-eight articles displayed adequate reporting of electromyographic methodology and qualified for detailed review including a second quality assessment using a modified version of the Quality Index. These included six studies investigating the effect of foot posture, 12 the effect of foot orthoses and 20 the effect of footwear on lower limb muscle activity during walking or running. Meta-analysis was not conducted due to heterogeneity between studies. Some evidence exists that: (i) pronated feet demonstrate greater electromyographic activation of invertor musculature and decreased activation of evertor musculature; (ii) foot orthoses increase activation of tibialis anterior and peroneus longus, and may alter low back muscle activity; and (iii) shoes with elevated heels alter lower limb and back muscle activation. Most studies reported statistically significant changes in electromyographic activation, although these findings were often not well supported when confidence intervals were calculated. Most important, however, is that there is a need for further research of more rigorous methodological quality, including greater consensus regarding standards for reporting of electromyographic parameters.