The acute and longitudinal effects of a weighted exo-skeleton on the performance of the power clean
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The power clean exercise is commonly prescribed to athletes involved in strength and power sports due to the kinematic similarities that this exercise has to key phases during jumping and sprinting (e.g. explosive hip, knee and ankle extension). Another popular method to improve athletic performance and lower body power is training with a weighted vest (WV) (i.e. centralised loading) as it allows individuals to perform sports specific movements such as jumping and sprinting in an overloaded fashion. Weighted vest training may also be a possible alternative loading method that could allow individuals to continue to train with full body explosive exercises without being limited by the technique and mobility demands. However, it is currently unknown what effect this loading method has on full body explosive movements such as the power clean. Therefore this thesis sought to investigate the acute and longitudinal effects of centralised loading on the performance of the power clean exercise and athletic performance. The purpose of the first study was to determine the optimal load to be worn during the performance of the power clean exercise. This was achieved by comparing the acute kinematic and kinetic effects of performing the power clean with loads of 50% and 70% 1RM across three conditions in nine recreationally trained males; 1) no Exo-skeleton, 2) 5% bodyweight Exo-skeleton and, 3) 12% body mass Exo-skeleton. Four of the kinematic variables measured were technique variables which were; 1) most forward position to catch (DxL), 2) start position to catch (DxT), 3) start position to beginning of 2nd pull (Dx2), and 4) 2nd pull position to catch (DxV). It was concluded that the optimal Exo-skeleton load to be worn during the power clean was a load ~12% of a lifter’s bodyweight and such loading may positively influence kinematic and kinetic variables during power clean performance. Following the results from study one, a five week power clean training intervention was devised to determine and compare the longitudinal kinematic, kinetic and performance effects of wearing a weighted Exo-skeleton vs. no Exo-skeleton. Sixteen resistance trained males were randomly assigned to either a no Exo-skeleton or a 12% bodyweight Exo-skeleton group. Training with the 12% Exo-skeleton resulted in a number of desirable technique changes (as determined by the variables noted above) that included increases in the rearward displacement of the barbell, increases in barbell velocity, and improved peak power outputs. Furthermore, the cumulative effect of improved lifting kinematics, barbell velocity, and PP resulted in the 12% Exo-skeleton group improving the CMJ by 8.5% and 1RM power clean performance by 4.6%. Conversely, the no Exo-skeleton group demonstrated only a mild increase in 1RM power clean performance (1.9%) and a decrease in CMJ performance (-1.5%). In conclusion, training with a 12% Exo-skeleton is a viable alternative loading method for resistance trained males who wish to improve their power clean ability (both technique and performance) and CMJ performance.