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Lower extremity joint kinetics and lumbar curvature during squat and stoop lifting.

Hwang S, Kim Y, Kim Y - BMC Musculoskelet Disord (2009)

Bottom Line: The bi-articular antagonist muscles' co-contraction around the knee joint during the squat lifting and the eccentric co-contraction of the gastrocnemius and the biceps femoris were found important for maintaining the straight leg during the stoop lifting.Differently, only the hip moment had significant correlation with the lumbar joint in the stoop lifting.In conclusion, the knee extension which is prominent kinematics during the squat lifting was produced by the contributions of the kinetic factors from the hip and ankle joints(extensor moment and power generation) and the lumbar extension which is prominent kinematics during the stoop lifting could be produced by the contributions of the knee joint kinetic factors(flexor moment, power absorption, bi-articular muscle function).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering and Institute of Medical Engineering, Yonsei University, Seoul, South Korea. shhwang@yonsei.ac.kr

ABSTRACT

Background: In this study, kinematics and kinetics of the lower extremity joint and the lumbar lordosis during two different symmetrical lifting techniques(squat and stoop) were examined using the three-dimensional motion analysis.

Methods: Twenty-six young male volunteers were selected for the subjects in this study. While they lifted boxes weighing 5, 10 and 15 kg by both squat and stoop lifting techniques, their motions were captured and analyzed using the 3D motion analysis system which was synchronized with two forceplates and the electromyographic system. Joint kinematics was determined by the forty-three reflective markers which were attached on the anatomical locations based on the VICON Plug-in-Gait marker placement protocol. Joint kinetics was analyzed by using the inverse dynamics. Paired t-test and Kruskal-Wallis test was used to compare the differences of variables between two techniques, and among three different weights. Correlation coefficient was calculated to explain the role of lower limb joint motion in relation to the lumbar lordosis.

Results: There were not significant differences in maximum lumbar joint moments between two techniques. The hip and ankle contributed the most part of the support moment during squat lifting, and the knee flexion moment played an important role in stoop lifting. The hip, ankle and lumbar joints generated power and only the knee joint absorbed power in the squat lifting. The knee and ankle joints absorbed power, the hip and lumbar joints generated power in the stoop lifting. The bi-articular antagonist muscles' co-contraction around the knee joint during the squat lifting and the eccentric co-contraction of the gastrocnemius and the biceps femoris were found important for maintaining the straight leg during the stoop lifting. At the time of lordotic curvature appearance in the squat lifting, there were significant correlations in all three lower extremity joint moments with the lumbar joint. Differently, only the hip moment had significant correlation with the lumbar joint in the stoop lifting.

Conclusion: In conclusion, the knee extension which is prominent kinematics during the squat lifting was produced by the contributions of the kinetic factors from the hip and ankle joints(extensor moment and power generation) and the lumbar extension which is prominent kinematics during the stoop lifting could be produced by the contributions of the knee joint kinetic factors(flexor moment, power absorption, bi-articular muscle function).

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Joint angles in sagittal plane during squat and stoop lifting. Joint angles of waist, hip, knee, and ankle were not significant different in different weights (5, 10, and 15 kg), however the range of motion(ROM) of each joint was different between the two lifting methods (squat and stoop).
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Figure 1: Joint angles in sagittal plane during squat and stoop lifting. Joint angles of waist, hip, knee, and ankle were not significant different in different weights (5, 10, and 15 kg), however the range of motion(ROM) of each joint was different between the two lifting methods (squat and stoop).

Mentions: The subjects lifted the objects as their own comfortable speed and the mean speeds were 0.59 m/s(± 0.14) in squat lifting and 0.60 m/s(± 0.10) in stoop lifting. Figure 1 represents the lower extremity joint angles on the sagittal plane during lifting. Though different weights were lifted, significant differences were not found in the range of motions(ROMs). However, between two techniques, ROMs for the same joints showed significant difference. The knee joint ROM showed the largest difference between two techniques(Figure 1).


Lower extremity joint kinetics and lumbar curvature during squat and stoop lifting.

Hwang S, Kim Y, Kim Y - BMC Musculoskelet Disord (2009)

Joint angles in sagittal plane during squat and stoop lifting. Joint angles of waist, hip, knee, and ankle were not significant different in different weights (5, 10, and 15 kg), however the range of motion(ROM) of each joint was different between the two lifting methods (squat and stoop).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2651112&req=5

Figure 1: Joint angles in sagittal plane during squat and stoop lifting. Joint angles of waist, hip, knee, and ankle were not significant different in different weights (5, 10, and 15 kg), however the range of motion(ROM) of each joint was different between the two lifting methods (squat and stoop).
Mentions: The subjects lifted the objects as their own comfortable speed and the mean speeds were 0.59 m/s(± 0.14) in squat lifting and 0.60 m/s(± 0.10) in stoop lifting. Figure 1 represents the lower extremity joint angles on the sagittal plane during lifting. Though different weights were lifted, significant differences were not found in the range of motions(ROMs). However, between two techniques, ROMs for the same joints showed significant difference. The knee joint ROM showed the largest difference between two techniques(Figure 1).

Bottom Line: The bi-articular antagonist muscles' co-contraction around the knee joint during the squat lifting and the eccentric co-contraction of the gastrocnemius and the biceps femoris were found important for maintaining the straight leg during the stoop lifting.Differently, only the hip moment had significant correlation with the lumbar joint in the stoop lifting.In conclusion, the knee extension which is prominent kinematics during the squat lifting was produced by the contributions of the kinetic factors from the hip and ankle joints(extensor moment and power generation) and the lumbar extension which is prominent kinematics during the stoop lifting could be produced by the contributions of the knee joint kinetic factors(flexor moment, power absorption, bi-articular muscle function).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering and Institute of Medical Engineering, Yonsei University, Seoul, South Korea. shhwang@yonsei.ac.kr

ABSTRACT

Background: In this study, kinematics and kinetics of the lower extremity joint and the lumbar lordosis during two different symmetrical lifting techniques(squat and stoop) were examined using the three-dimensional motion analysis.

Methods: Twenty-six young male volunteers were selected for the subjects in this study. While they lifted boxes weighing 5, 10 and 15 kg by both squat and stoop lifting techniques, their motions were captured and analyzed using the 3D motion analysis system which was synchronized with two forceplates and the electromyographic system. Joint kinematics was determined by the forty-three reflective markers which were attached on the anatomical locations based on the VICON Plug-in-Gait marker placement protocol. Joint kinetics was analyzed by using the inverse dynamics. Paired t-test and Kruskal-Wallis test was used to compare the differences of variables between two techniques, and among three different weights. Correlation coefficient was calculated to explain the role of lower limb joint motion in relation to the lumbar lordosis.

Results: There were not significant differences in maximum lumbar joint moments between two techniques. The hip and ankle contributed the most part of the support moment during squat lifting, and the knee flexion moment played an important role in stoop lifting. The hip, ankle and lumbar joints generated power and only the knee joint absorbed power in the squat lifting. The knee and ankle joints absorbed power, the hip and lumbar joints generated power in the stoop lifting. The bi-articular antagonist muscles' co-contraction around the knee joint during the squat lifting and the eccentric co-contraction of the gastrocnemius and the biceps femoris were found important for maintaining the straight leg during the stoop lifting. At the time of lordotic curvature appearance in the squat lifting, there were significant correlations in all three lower extremity joint moments with the lumbar joint. Differently, only the hip moment had significant correlation with the lumbar joint in the stoop lifting.

Conclusion: In conclusion, the knee extension which is prominent kinematics during the squat lifting was produced by the contributions of the kinetic factors from the hip and ankle joints(extensor moment and power generation) and the lumbar extension which is prominent kinematics during the stoop lifting could be produced by the contributions of the knee joint kinetic factors(flexor moment, power absorption, bi-articular muscle function).

Show MeSH
Related in: MedlinePlus