Evaluation of resistance training equipment using three dimensional musculoskeletal modelling focusing on the biomechanical and anthropometric considerations of the enduser

Abstract

The main goal of this study was to evaluate whether three dimensional musculoskeletal modelling (3D) is effective in assessing the safety and efficacy of resistance training equipment. The focus of the evaluation was on the biomechanical and anthropometric considerations of the end-user. 3D musculoskeletal modelling was used to evaluate four pieces of resistance training equipment, namely the seated biceps curl, abdominal crunch, seated row and chest press. Three anthropometric cases were created; these represented a traditional 5th percentile female as well as a 50th and 95th percentile male based on body mass index (BMI). Resistance on the training machines was set at fifty percent of the functional strength one repetition maximum (1RM), for each anthropometric case and piece of exercise equipment two repetitions were performed except for the abdominal crunch model during which four repetitions were simulated. Each piece of equipment presented unique challenges. In three of the four studies (seated biceps curl, seated row and chest press) the default model created by the modelling software was not adequate to solve the forward dynamics simulations and thus adjustments had to be made to the default model in order to complete the modelling process. 3D musculoskeletal modelling by means of LifeModelerTM software was able to identify some potential risk for musculoskeletal injury as well as highlight the discrepancies between the anthropometric cases, specifically the accommodation of the 5th percentile female and the machines’ engineered adjustability. 3D musculoskeletal modelling has the potential to indicate shortcomings in resistance training equipment design. Therefore it appears as if 3D musculoskeletal modelling can be used to evaluate resistance training equipment design however the limitations as indicated by this study must be taken into consideration especially when using default models.AFRIKAANS: Die doel van die studie was om die effektiwiteit van driedimensionele (3D) muskuloskeletale modellering te evalueer in terme van die tegniek se vermoë om die veiligheid en doeltreffendheid van weerstands oefenapparaat te evalueer. Die fokus van die evaluasie was op die biomeganiese en antropometriese oorwegings van die end-gebruiker. 3D muskuloskeletale modellering was gebruik in die evaluasie van vier weerstands oefenapparate genaamd die sittende biceps krul, abdominale krul, sittende roei en sittende borsstoot. Drie antropometriese gevalle is geskep, die het ‘n tradisionele 5e persentiel vrou, sowel as ‘n 50ste en 95ste persentiel man voorgestel en was gebasseer op liggaamsmassa indeks waardes. Die eksterne weerstand van die apparaat was bepaal teen vyftig persent van die funsionele krag een-repetisie- maksimum vir elk van die antropometriese gevalle en twee repetisies is uitgevoer behalwe vir die abdominale krul waartydens vier repetisies gesimuleer is. Elke apparaat het unieke uitdagings gestel. In drie van die vier studies (sittende biceps krul, sittende roei en sittende borsstoot) was die standaard model van die sagteware onvoldoende om die voorwaards dinamiese simulasie op te los en moes aanpassings aan die modelle gemaak word vir suksesvolle simulasies. Die modellerings proses met die Lifemodeler™ sagteware kon potensiële risiko vir muskuloskeletale besering sowel as verskille tussen die verskeie antropometriese gevalle uitwys. Dit was veral opvallend vir die akkomodasie van die 5e persentiel vrou asook betreffende die apparaat se vervaardigde verstelbaarheid. 3D muskuloskeletale modellering beskik oor die vermoë om voorstelle vir verbetering in die ontwerp van weerstands oefenapparaat uit te wys. Dit blyk dus dat 3D muskuloskeletale modellering beslis gebruik kan word vir die evaluasie van weerstands oefenapparaat ontwerp, die beperkings van die studie moet egter in gedagte gehou word, veral wanneer standaard modelle gebruik word.