The geometric curvature of the spine of runners during maximal incremental effort test

A ToF-based system for recording human sagittal back shape

BACKGROUND

The sagittal back shape (SBS) of the human body, which should be highly consistent with the spinal morphology along the internal spine line, also presents an s-shaped curve.

OBJECTIVE

We propose a novel time-of-flight (ToF) based system to record the s-shaped SBS of the human body, which was simple, inexpensive, and non-invasive.

RESULTS

The system was composed of a bottom plate, an upright post, a vertical rod, dozens of horizontal measuring rods, and a ToF sensor. The experimental results showed that the system supported to obtain the s-shaped SBS of the human body with satisfactory accuracy.

CONCLUSIONS

The ToF-based system for recording human sagittal back shape will be useful for routine screening of spinal physiological conditions in schools, as well as for e.g. digital garment design, and special seat-back design.

Effects of sports bra and footwear on vertebral posture during walking and running

Little attention has been given to factors which affects women running, such as proper footwear and breast support and their effects on spine. The objective of study was to analyse the influence of different breast support and footwear on vertebral posture during walking and running. Seventeen women (x¯ = 23.51; SD = 3.70 years) performed a treadmill walking (5 km/h) and running (7 and 10 km/h) with different footwear (barefoot, minimalist and traditional) and breast support (bare breast, everyday bra and sports bra) conditions. Spine movements were analyzed using three cameras in grayscale video mode, positioned behind the participant to register reflective markers fixed in the vertebrae. From the 3D coordinates of the trunk markers we computed, for the whole gait cycle (C) and for the average gait posture (neutral curve-NC) the maximal (M) thoracic (T) kyphosis and lateral flexion, and the maximal lumbar (L) lordosis and lateral flexion. Frontal plane: bare breast presented higher lumbar NC than the everyday bra and sports bra, higher MLC than the sports bra and lower MTC than the everyday bra and sports bra. Barefoot presented higher MTC than minimalist. Sagittal plane: bare breast presented lower MTC than the sports bra. Barefoot presented higher lumbar NC than the minimalist and traditional footwear and higher MLC than the minimalist and traditional ones. The sports bra increased curvatures in the thoracic spine that were rectified during bare breast conditions. In addition, both footwears were able to maintain the natural curvatures of the spine in the lumbar.

Quantitative evaluation of linked rigid-body representations of the trunk

BACKGROUND

The trunk is often simplified as a small number of rigid-body segments to reduce the complexity of its multi-segmental structure. However, such rigid-body representations of the trunk may overlook its flexible movement owing to its multi-segmental structure.

RESEARCH QUESTION

The purpose of this study is to quantitatively assess the effects of the deformability on the resultant trunk kinematics when the trunk is modeled with numerous rigid-body segments.

METHODS

Three-dimensional kinematic data of 10 male subjects were obtained during static and dynamic trials. The trunk in both static and dynamic trials was modeled as a single rigid-body segment or as two, three, or six linked rigid-body segments, and a non-linear optimization analysis was performed to minimize the difference between the actual and modeled position data. Position errors were evaluated to assess the difference in three-dimensional positions between the actual and modeled data for each model. The total angular displacement was evaluated to examine to what extent each model describes the actual multi-segmental trunk movement.

RESULTS

The position error between the modeled and actual kinematic data of the trunk was up to 12 mm and 11 mm when the trunk was simplified as one segment, but the error decreased to 5 mm and 7 mm when the trunk was modeled with six segments during the static and dynamic trials, respectively. The total angular displacement increased as the number of rigid-body segments increased during both trials.

SIGNIFICANCE

These results imply that a small number of linked rigid-body representations underestimates the actual multi-segmental trunk movement during dynamic movement. These findings are useful in determining the optimal number of rigid-body segments for analysis of the trunk.

Normative 3D opto-electronic stereo-photogrammetric posture and spine morphology data in young healthy adult population

Design: Observational cross-sectional study. The current study aims to yield normative data: i.e., the physiological standard for 30 selected quantitative 3D parameters that accurately capture and describe a full-skeleton, upright-standing attitude. Specific and exclusive consideration was given to three distinct categories: postural, spine morphology and pelvic parameters. To capture such 3D parameters, the authors selected a non-ionising 3D opto-electronic stereo-photogrammetric approach. This required the identification and measurement of 27 body landmarks, each specifically tagged with a skin marker. As subjects for the measurement of these parameters, a cohort of 124 asymptomatic young adult volunteers was recruited. All parameters were identified and measured within this group. Postural and spine morphology data have been compared between genders. In this regard, only five statistically significant differences were found: pelvis width, pelvis torsion, the “lumbar” lordosis angle value, the lumbar curve length, and the T12-L5 anatomically-bound lumbar angle value. The “thoracic” kyphosis mean angle value was the same in both sexes and, even if, derived from skin markers placed on spinous processes it resulted in perfect agreement with the X-ray based literature. As regards lordosis, a direct comparison was more difficult because methods proposed in the literature differ as to the number and position of vertebrae under consideration, and their related angle values. However, when the L1 superior–L5 inferior end plate Cobb angle was considered, these results aligned strongly with the existing literature. Asymmetry was a standard postural-spinal feature for both sexes. Each subject presented some degree of leg length discrepancy (LLD) with μ = 9.37mm. This was associated with four factors: unbalanced posture and/or underfoot loads, spinal curvature in the frontal plane, and pelvis torsion. This led to the additional study of the effect of LLD equalisation influence on upright posture, relying on a sub-sample of 100 subjects (51 males, 49 females). As a result of the equalisation, about 82% of this sub-sample showed improvement in standing posture, mainly in the frontal plane; while in the sagittal plane less than 1/3 of the sub-sample showed evidence of change in spinal angles. A significant variation was found in relation to pelvis torsion: 46% of subjects showed improvement, 49% worsening. The method described in study presents several advantages: non-invasive aspect; relatively short time for a complete postural evaluation with many clinically useful 3D and 2D anatomical/biomechanical/clinical parameters; analysis of real neutral unconstrained upright standing posture.

Quantitative assessment of trunk deformation during running

The trunk has a multi-segmental structure and is composed of the cervical, thoracic, and lumber spines and surrounding soft tissue elements; this allows flexible deformation during dynamic movements. The purpose of this study was to quantitatively assess trunk deformation during dynamic movement. Ten male subjects performed running at four different speeds: 8km/h, 10km/h, 12km/h, and 14km/h. Forty reflective markers were placed on the backs of these individuals to define 56 small triangular areas, and three-dimensional kinematic data was recorded with a motion capture system. The coefficients of variation (CV) of the horizontal and vertical lengths between two adjacent markers and the standard deviation (SD) of the normal vectors of triangular areas were calculated as measures for translational and angular trunk deformation, respectively. Up to about 14% of CV and 78° of SD appeared as the measure of translational and angular deformation, respectively. These results imply that the trunk underwent a significant amount of position-specific deformation. These findings would be useful in the construction of an optimal trunk segment model to represent the complex and flexible trunk movement during dynamic movements.

The geometric curvature of the spine during the sirshasana, the yoga's headstand

This study analysed the behaviour of the geometric curvature of the spine during sirshasana. The position of dorsal retroreflective markers was computed via stereophotogrammetric analysis in six males and five females (29.4 ± 8.8 years, 63.0 ± 11.4 kg, 1.66 ± 0.08 m [average ± standard deviation]). The spinal points were projected onto the sagittal and frontal planes of the trunk, a polynomial was fitted to the data and the two-dimensional geometric curvature was quantified. The inferior lumbar lordosis decreased compared to the orthostatic position and gait, which may favour the posterior protrusion of the lumbar spinal nucleus pulposus in people with posterior herniation. The lateral deviation at the middle of the thoracic spine increases during sirshasana, which may reflect increased difficulties for postural control and spinal loads. It could be useful for promoting positive spinal structural and functional chronic adaptations for healthy participants, if the yoga programme is carefully planned and the spinal alignment is carefully monitored during a headstand. However, it may aggravate some spinal diseases, especially scoliosis.