Purpose:Totesttheeffectivenessofsittingsurfaceswithvariedamountsofstabilityonmuscleactivityandenergyexpenditure.Methods:Usingawithin-participantsrepeatedmeasuresdesign,11healthyyoung-adultfemales(age=20.0±1.8years)weremeasuredusingindirectcalorimetrytoassessenergyexpenditure,andelectromyographytoassessmuscularactivationintrunkandlegmusculatureunder3differentsittingsurfaces:flat-firmsurface,air-filledcushion,andastabilityball.Datawereanalyzedusingrepeatedmeasuresanalysisofvariancewithfollow-uppairwisecontrastsusedtodeterminethespecificeffectsofsittingsurfaceonmuscleactivationandenergyexpenditure.Results:Significantlygreaterenergyexpenditurewasrecordedforthestabilityball(p=0.01)andthecushion(p=0.03)overtheflatsurface(10.4%and9.6%greater,respectively),withnodifferencesbetweentheballandthecushion.Boththeballandthecushionproducedhighertibialisanterioractivationovertheflatsurface(1.09and0.63root-mean-squaremillivolts(RMSmv),respectively),whilethestabilityballproducedhighersoleusactivityoverbothcushionandflatsurfaces(3.97and4.24RMSmv,respectively).Additionally,thecushionelicitedhigheradductorlongusactivityovertheballandflatsurfaces(1.76and1.81RMSmv,respectively),butnotrunkmusculaturedifferenceswererevealed.Conclusion:Compliantsurfacesresultedinhigherlevelsofmuscularactivationinthelowerextremitiesfacilitatingincreasedcaloricexpenditure.Giventheincreasingtrendsinsedentarycareersandtheincreasesinobesity,thisisanimportantfindingtovalidatethemeritsofactivesittingfacilitatingincreasedcaloricexpenditureandmuscleactivation.
