Abstract
AbstractThis study investigated the effect of the inertial component of the resistance (INERTIA) at different intensity levels (LOAD) on force (FORCE), velocity (VELOCITY), power (POWER), and the muscle activity of the pectoralis major (EMGPM), anterior deltoid (EMGDA) and triceps brachii (EMGTB) muscles during a chest press exercise.A motor-driven exercise apparatus was programmed to offer resistance with different inertial profiles over the range of movement (ROM): gravitational-type constant inertia (IFULL); no-inertia (IZERO); linearly descending inertia along theROM(IVAR). Nine healthy adults performed five, maximal-effort, explosive movements with each inertial profile at 30, 50 and 70% of their 1 repetition maximum. Meanwhile, theEMGPM,EMGDAandEMGTBsignals were obtained jointly with theFORCE, VELOCITYandPOWERreadings returned by the exercise apparatus.One-dimensional statistical non-parametric maps based on 2-way repeated measures ANOVA (SnPM) were employed to evaluate the effect ofLOADandINERTIAon the collected timeseries. Paired t-tests were then used as post-hoc tests on the portions of theROMdenoting significant differences in theSnPM.HigherLOADresulted in elevated outcomes over large portions of theROMin all the investigated timeseries. Compared toIFULL,IZEROallowed greaterVELOCITYat the cost of lowerFORCEthroughout theROM, whileIVAR, despite the lowerVELOCITYthanIZERO, resulted in higherFORCEandPOWERoutput. In addition,IZEROandIVARelevatedEMGTBat the end of theROMwith respect toIFULL.IVARovercame bothIFULLandIZEROin terms ofFORCEandPOWER, which indicates that variable inertial profiles might be effectively integrated into resistance exercise programs. Ultimately, this study suggested thatINERTIAacts independently to the imposedLOADon theFORCE, VELOCITYandPOWERproduction. Coaches and therapists are encouraged to account for the type ofINERTIAas one of the parameters considered during the exercise selection for their athletes or patients.
Publisher
Cold Spring Harbor Laboratory