Moon, Youngjin
(Department of Sports Science, Chungnam National University)
,
Moon, Jeheon
(Department of Sports Science, Korea Institute of Sport Science, Korea Sports Promotion Foundation)
Objective: The purpose of this study was to examine the effect of increase in barbell weight on closely related variable to the anterior cruciate ligament (ACL) injury which are knee joint kinematics, joint load, joint moment, and maximum load attainment point during snatch of the weight lifting. Me...
Objective: The purpose of this study was to examine the effect of increase in barbell weight on closely related variable to the anterior cruciate ligament (ACL) injury which are knee joint kinematics, joint load, joint moment, and maximum load attainment point during snatch of the weight lifting. Method: The subjects of the study were 10 male Korean national weight lifting athletes (69 kg 5, 77 kg 5; age: $21.80{\pm}3.91yrs.$, height: $168.00{\pm}4.06cm$, weight: $75.00{\pm}4.02kg$, career: $7.8{\pm}3.99yrs.$, snatch records: $168{\pm}4.06kg$). The weight of the barbell during the snatch operation was set at 70%, 75% and 80% of the highest records for each subject studied. Results: The result obtained from the one-way repeated measure ANOVA are as follows: With increased barbell weight, the extension moment of the left knee joint was higher in the 80% condition than the 70% (p<.001). However, other variables were not statistically significant difference. According to the factor analysis of the variables related to maximum load attainment point of the ACL major injury variables, the first sub-factor was the internal shear force, the posterior shear force, the abduction moment, and the muscle activity of the VL. The second sub-factor was the extension moment of the knee joint, compressive force, adduction moment, and the third sub-factor was the muscle activity of BF. Conclusion: These results indicate that the possibility of ACL injury can be lowered when performing a stable snatch movement.
Objective: The purpose of this study was to examine the effect of increase in barbell weight on closely related variable to the anterior cruciate ligament (ACL) injury which are knee joint kinematics, joint load, joint moment, and maximum load attainment point during snatch of the weight lifting. Method: The subjects of the study were 10 male Korean national weight lifting athletes (69 kg 5, 77 kg 5; age: $21.80{\pm}3.91yrs.$, height: $168.00{\pm}4.06cm$, weight: $75.00{\pm}4.02kg$, career: $7.8{\pm}3.99yrs.$, snatch records: $168{\pm}4.06kg$). The weight of the barbell during the snatch operation was set at 70%, 75% and 80% of the highest records for each subject studied. Results: The result obtained from the one-way repeated measure ANOVA are as follows: With increased barbell weight, the extension moment of the left knee joint was higher in the 80% condition than the 70% (p<.001). However, other variables were not statistically significant difference. According to the factor analysis of the variables related to maximum load attainment point of the ACL major injury variables, the first sub-factor was the internal shear force, the posterior shear force, the abduction moment, and the muscle activity of the VL. The second sub-factor was the extension moment of the knee joint, compressive force, adduction moment, and the third sub-factor was the muscle activity of BF. Conclusion: These results indicate that the possibility of ACL injury can be lowered when performing a stable snatch movement.
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제안 방법
A three dimensional kinematic analysis was conducted using Qualisys infrared camera system (Oqus 7+, AB, Gothenburg, Sweden) at the sampling frequency of 120 Hz. The ground reaction force was calculated using Kistler force plates Type 9287BA, AG, Winterthur, Switzerland) at sampling frequency of 1,200 Hz.
017. Similarly, Factor analysis was performed to identify the Tpeak components for major ACL injury. Factor extraction was based on principal component and varimax rotation was performed.
The aim of our study was to analyze the possibility of ACL injury through change in moment and load of the knee joints with the increase in load in a weightlifting motion. We wanted to ascertain the Tpeak of the major kinematic factors that increase the ACL load.
The athletes who were ready after the warm-up had their static posture capture in an anatomical posture for 5 seconds to estimate the center of mass (COM) of the human body.
Therefore, it is necessary to research the possibility of ACL injuries and clarify the mechanism of injury by performing lifting operation where a high weighted barbell is lifted above the head. The purpose of this study was to analyze the possibility of ACL injury i.e. change in moment and load of the knee joints when increasing the weight of the barbell, and also to ascertain maximum load attainment point (Tpeak) of the major biomechanical factors that increase the ACL load.
The subjects who participated in this study were first informed about the purpose of the study, the process of experiment, and the protection of personal information verbally and signed the consent form.
대상 데이터
The athletes participating in this study regularly participate in weightlifting competitions and all have won first place in national competitions. The participants reported no history of pathological abnormalities or injuries to the musculoskeletal system, including knee joints, during the past six months. All participants read the research guide, signed the consent form and participated in the experiment voluntarily and were approved by the Bio-Research Ethics Committee of the Korea Institute of Sport Science (KISS-201511-IFS-034-P1).
데이터처리
A one-way ANOVA of repeated measurements was performed to analyze the differences in the dependent variables (ROM, angular velocity, load, moment) according to the increase in the barbell weight (70%, 75%, and 80%). If a statistically significant difference was observed, post-hoc analysis was used to confirm the difference between the samples and the significance level was set to p<.
Table 1. Results of One- way repeated measure ANOVA of factors influencing the Knee joint with the increase in load. Mean ± SD
이론/모형
, Rockville, MD, USA) was used to calculate the range of motion, maximum angular velocity, shear force and moment variables of the knee joint. The Tpeak factor affecting the ACL injury was calculated using Matlab (ver. R2009b, The MathWorks, Inc., Natick, MA, USA).
The range of motion (ROM) of the knee joint and the maximum angular velocity corresponding to the kinematic variables were calculated by the Cardan sequence method using 3D marker coordinates. The flexion / extension movement of the knee joint was set to the x axis, the abduction / abduction was set to the y axis, and the internal/external rotation was set to the z axis.
성능/효과
According to the results of this study, the maximum medial shear force of the left and right knee joints was 477.2 N and the maximum posterior shear force was 963.1 N which was up to the personal best weight of 70%, 75%, and 80%.
, 2005; Kernozek & Ragan, 2008). However, the results of our factor analysis indicate that the Tpeak of BF was composed of the third sub-factor together with the external rotation moment and was delayed about 0.4 second compared to Tpeak of VL where the time-delayed characteristic of the co-contraction was observed. These results suggest that the effect of co-contraction of quadriceps femoris and BF should be considered from a different point of view on the reduction of ACL load.
Events such as weightlifting need to consider factors that affect ACL injuries because of the high strains that intersect around the knee joints when lifting heavy weights. In order to achieve the purpose of the study, we analyzed the load, moment, VL and BF muscle activity of the knee joints by increasing barbell weight, but no statistically significant difference between weights were noted, except for the extension moment of the left knee joint.
All experiments were conducted at the same place and time, and the room temperature was set at 23℃ using an indoor air conditioner. The schedule of the experiment was finalized a month ago after consultation with the subjects and their coaches, and were asked to perform 80% of their highest weightlifting record. Here, 80% weight was considered to be the highest weight that a subject can perform in laboratory setting based on their physical condition at the time of experiment.
There was no statistically significant difference in the ROM of the knee joint and the maximum angular velocity according to the weight of the barbell at 70%, 75%, and 80% of the personal best (Table 1).
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