Foot positioning instruction, initial vertical load position and lifting technique: effects on low back loading

Kingma, Idsart; Bösch, T.; Bruins, Louis; Dieën, Jaap H. van

doi:10.1080/00140130410001714742

Cited by 98 publications

(92 citation statements)

References 39 publications

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“…Farfan et al [9,11] measured TMF under compression (maximum of 573 N) in degenerated segments; their results were comparable to the present results. We used a constant compressive load level of 1,600 N to allow for comparison with the load levels found in daily physiological loading [16] and to compare with previous work [5,6]. While this force may seem high, it is not very high compared to that estimated in vivo compression.…”

Section: Discussionmentioning

confidence: 99%

“…Calibration of axial compression was performed using a load cell (Hottinger Baldwin Messtechnik Ó , Force Transducer Type C2, Darmstadt, Germany). The 1,600 N preload was selected to allow for comparison with load levels found in daily physiological loading [16] and to compare with previous work [5,6], without causing compressive failure [7]. Subsequently, torsion load was applied with a constant rate of 3.0°per min by pulling on a metal wire, which was securely fixed to the part of the casting mold that contained the caudal vertebral body (Fig.…”

Section: Biomechanical Testingmentioning

confidence: 99%

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Torsion biomechanics of the spine following lumbar laminectomy: a human cadaver study

et al. 2013

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Purpose Lumbar laminectomy affects spinal stability in shear loading. However, the effects of laminectomy on torsion biomechanics are unknown. The purpose of this study was to investigate the effect of laminectomy on torsion stiffness and torsion strength of lumbar spinal segments following laminectomy and whether these biomechanical parameters are affected by disc degeneration and bone mineral density (BMD). Methods Ten human cadaveric lumbar spines were obtained (age 75.5, range 59-88). Disc degeneration (MRI) and BMD (DXA) were assessed. Disc degeneration was classified according to Pfirrmann and dichotomized in mild or severe. BMD was defined as high BMD (Cmedian BMD) or low BMD (\median BMD). Laminectomy was performed either on L2 (59) or L4 (59). Twenty motion segments (L2-L3 and L4-L5) were isolated. The effects of laminectomy, disc degeneration and BMD on torsion stiffness (TS) and torsion moments to failure (TMF) were studied.Results Load-displacement curves showed a typical bi-phasic pattern with an early torsion stiffness (ETS), late torsion stiffness (LTS) and a TMF. Following laminectomy, ETS decreased 34.1 % (p \ 0.001), LTS decreased 30.1 % (p = 0.027) and TMF decreased 17.6 % (p = 0.041). Disc degeneration (p \ 0.001) and its interaction with laminectomy (p \ 0.031) did significantly affect ETS. In the mildly degenerated group, ETS decreased 19.7 % from 7.6 Nm/degree (6.4-8.4) to 6.1 Nm/degree (1.5-10.3) following laminectomy. In the severely degenerated group, ETS decreased 22.3 % from 12.1 Nm/degree (4.6-21.9) to 9.4 Nm/degree (5.6-14.3) following laminectomy. In segments with low BMD, TMF was 40.7 % (p \ 0.001) lower than segments with high BMD [34.9 Nm (range 23.7-51.2) versus 58.9 Nm (range 43.8-79.2)]. Conclusions Laminectomy affects both torsion stiffness and torsion load to failure. In addition, torsional strength is strongly affected by BMD whereas disc degeneration affects torsional stiffness. Assessment of disc degeneration and BMD pre-operatively improves the understanding of the biomechanical effects of a lumbar laminectomy.

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Section: Discussionmentioning

confidence: 99%

Section: Biomechanical Testingmentioning

confidence: 99%

Torsion biomechanics of the spine following lumbar laminectomy: a human cadaver study

et al. 2013

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“…Mainly due to muscle forces, the spine is already subjected to forces of this magnitude when the trunk is inclined about 45°forward. When lifting a 10 kg object from ground level, compression forces can increase up to about 5,000 N [13]. Failure compressive loads in human cadaveric spines are on average 3,000 N [6].…”

Section: Discussionmentioning

confidence: 99%

“…Failure compressive loads in human cadaveric spines are on average 3,000 N [6]. The compression load of 1,600 N was also selected to allow for comparison with previous work [2-4, 24, 26] and was sufficiently large to simulate physiological loading [13][14][15], but low enough to avoid damage due to compression forces alone [6].…”

Section: Discussionmentioning

confidence: 99%

Which factors prognosticate rotational instability following lumbar laminectomy?

Bisschop

Kingma²,

Bleys³

et al. 2013

Eur Spine J

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Purpose Reduced strength and stiffness of lumbar spinal motion segments following laminectomy may lead to instability. Factors that predict shear biomechanical properties of the lumbar spine were previously published. The purpose of the present study was to predict spinal torsion biomechanical properties with and without laminectomy from a total of 21 imaging parameters. Method Radiographs and MRI of ten human cadaveric lumbar spines (mean age 75.5, range 59-88 years) were obtained to quantify geometry and degeneration of the motion segments. Additionally, dual X-ray absorptiometry (DXA) scans were performed to measure bone mineral content and density. Facet-sparing lumbar laminectomy was performed either on L2 or L4. Spinal motion segments were dissected (L2-L3 and L4-L5) and tested in torsion, under 1,600 N axial compression. Torsion moment to failure (TMF), early torsion stiffness (ETS, at 20-40 % TMF) and late torsion stiffness (LTS, at 60-80 % TMF) were determined and bivariate correlations with all parameters were established. For dichotomized parameters, independent-sample t tests were used. Results Univariate analyses showed that a range of geometric characteristics and disc and bone quality parameters were associated with torsion biomechanical properties of lumbar segments. Multivariate models showed that ETS, LTS and TMF could be predicted for segments without laminectomy (r 2 values 0.693, 0.610 and 0.452, respectively) and with laminectomy (r 2 values 0.952, 0.871 and 0.932, respectively), with DXA-derived measures of bone quality and quantity as the main predictors. Conclusions Vertebral bone content and geometry, i.e. intervertebral disc width, frontal area and facet joint tropism, were found to be strong predictors of ETS, LTS and TMF following laminectomy, suggesting that these variables could predict the possible development of postoperative rotational instability following lumbar laminectomy. Proposed diagnostic parameters might aid surgical decision-making when deciding upon the use of instrumentation techniques.

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“…For these reasons, its use has been recently extended for prevention of osteoporosis, fractures and back pain [7]. Moreover, it helps the increase of bone density and thickness of ligaments, promoting tendon elasticity as well [8].…”

Section: Introductionmentioning

confidence: 99%

Improving the design of squat machine using motion capture and virtual prototyping

Mariti

Valentini

2011

Sports Eng

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Dynamic squat is one of the most executed fitness exercise. Its use is widespread both for rehabilitation and training purposes. Several typologies of the squat exercise can be performed. The most important are the front squat and the back squat. In the front squat the barbell is held in front of the body across the clavicles and deltoids, while in the back squat exercise the bar is held on the back of the body at the base of the neck. In this paper we will refer to dynamic back squat. The squat exercise can be performed with or without the help of a machine that has the scope of guiding the person during the movement and ensuring his stability and safety. The use of this type of machine is often necessary when the workout is heavy and the risk of incorrect exercise and injuries is high. On the other hand, the rigid structure of this device often overconstrains the lifting movement. From all these observations, the purpose of the paper is to discuss an alternative design of a mechanism able to maintain the advantage to allow a free-body execution and to preserve the safety of the athletes as well. The proposed mechanism has been designed starting from an anthropometric study on the squat movement. This has been performed by using a motion capture system and applying computer-aided engineering techniques. The design activity started from the experimental investigation of the trajectory of the barbell during the natural execution of the unrestricted back squat exercise. The tests have been performed on several subjects with different mass, anthropometry and gender. In a second phase, the data have been processed and analyzed and a specific mechanism, able to reproduce the natural trajectories, has been synthetized. Finally, the design and optimization of the entire structure has been performed through the use of virtual prototyping techniques.

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Foot positioning instruction, initial vertical load position and lifting technique: effects on low back loading

Cited by 98 publications

References 39 publications

Torsion biomechanics of the spine following lumbar laminectomy: a human cadaver study

Torsion biomechanics of the spine following lumbar laminectomy: a human cadaver study

Which factors prognosticate rotational instability following lumbar laminectomy?

Improving the design of squat machine using motion capture and virtual prototyping

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