Validity of the iLOAD® app for resistance training monitoring

Abstract

Background. This study aimed (I) to assess the inter-rater agreement for measuring themeanvelocity(MV)ofthebarbellwiththeiLOAD R app,and(II)tocomparethe magnitude of the MV and total work of a training session between the iLOAD R appand a linear encoder (reference method). Method. Sixteen young healthy individuals (four women and 12 men) were tested in twosessionsseparatedby48h.The10repetitionmaximum(RM)loadwasdetermined inthefirsttestingsessioninthehalfsquatexercise.Thesecondtestingsessionconsisted of 3 sets of 10 repetitions during the half squat exercise performed against the 10RM load. Both the iLOAD R app and a linear encoder were used to calculate the MV and total work of each training set. MV was recorded with the iLOAD R app by twoindependent researchers to evaluate the inter-rater agreement. Results.Trivialdifferencesandnearlyperfectcorrelationswereobservedbetweenraters fortheMVvaluescollectedunderindividualsets(effectsize[ES]≤0.02,r≥0.987),as well as for the whole training session (ES=0.01, r=0.997). Trivial-small differences andnearlyperfectcorrelationswereobservedbetweentheiLOAD R appandthelinearencoder( Chronojump,Barcelona,Spain)forMV(EV ≤0.25,r≥0.903)andtotalwork( ES≤0.05, r ≥0.973). Bland-Altman plots did not reveal heteroscedasticity of the errorsbetweentheiLOAD R appandthelinearencoderforMV(r2=0.010)andtotalwork ( r2 <0.001). Conclusions.iLOAD R isavalidsmartphoneappwhichcanprovidereal-timefeedback of the MV and total work completed in a set of multiple repetitions in the half squat exercise.