A wheelchair configuration with no seat slope , solid backrest mounted at @ degree ( @ degrees ) seat to back angle , and use of a solid seat insert with a flat foam cushion ( position two ) results in greater efficiency in foot propulsion for individuals with ABI than a wheelchair configuration with one inch of seat slope , solid backrest mounted at @ degree ( @ degrees ) seat to back angle , and no solid seat insert with a gel/foam contoured cushion ( position @ ) .