Male preference for a subtle posture cue that signals spawning readiness in female sticklebacks

We presented territorial male three-spined sticklebacks, Gasterosteus aculeatus, two stationary dummies simultaneously, each simulating an equally gravid female. Both dummies featured the head-up orientation indicative of a sexually receptive female but differed in more subtle aspects of posture. In one dummy the back and tail were moulded in a relaxed straight posture and the other was moulded with the raised tail and concave back posture (lordosis), which mating tests revealed to be a strong predictor of spawning readiness in females. Males courted both dummies but directed more to the lordosis posture. Male sticklebacks thus recognize and respond appropriately to relatively subtle features of female posture in addition to other cues such as the head-up angle and dorsal barring reported in earlier studies. Physiological or morphological constraints may make the lordosis posture a reliable, and hence relatively honest, indicator of spawning readiness in females. Males may therefore enhance their fitness by preferentially courting females that assume this posture. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Comparison of posture among adolescent male volleyball players and non-athletes

Due to high training loads and frequently repeated unilateral exercises, several types of sports training can have an impact on the process of posture development in young athletes. The objective of the study was to assess and compare the postures of adolescent male volleyball players and their non-training peers. The study group comprised 104 volleyball players while the control group consisted of 114 non-training individuals aged 14-16 years. Body posture was assessed by the Moiré method. The volleyball players were significantly taller, and had greater body weight and fat-free mass. The analysis of posture relative to symmetry in the frontal and transverse planes did not show any significant differences between the volleyball players and non-athletes. Postural asymmetries were observed in both the volleyball players and the control participants. Lumbar lordosis was significantly less defined in the volleyball players compared to non-training individuals while no difference was observed in thoracic kyphosis. All athletes demonstrated a loss of lumbar lordosis and an increase in thoracic kyphosis. Significant differences in anteroposterior curvature of the spine between the volleyball players and the non-athletes might be associated with both training and body height. Considering the asymmetric spine overloads which frequently occur in sports training, meticulous posture assessment in young athletes seems well justified.     

The effects of serotonin agonists on the hypothalamic regulation of sexual receptivity in Syrian hamsters

One brain region that has been implicated in the regulation of lordosis is the medial preoptic-anterior hypothalamic continuum (MPOA-AH). Previous studies have suggested that this zone may be part of the circuit mediating the effects of serotonin (5-HT) on sexual receptivity. In the present experiments, we investigated the role of 5-HT(1a/7) and 5-HT(2) receptor subtypes in the MPOA-AH in the control of lordosis. In two experiments, either 5-HT(1a/7) or 5-HT(2) agonists were injected unilaterally into the MPOA-AH of ovariectomized, hormonally primed female hamsters. In the first experiment, microinjections of the 5-HT(1a/7) agonist 8-hydroxy-2,9-(di-n-propylamino)tetralin resulted in an attenuation of the lordosis posture by causing a decrease in the mean lordosis duration and an increase in the number of lordosis episodes over the entire testing period. In the second experiment, microinjections of the 5-HT(2b/2c) agonist m-chlorophenylpiperazine did not result in any changes in sexual receptivity. However, microinjections of the 5-HT(2) agonist (2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl facilitated lordosis by increasing the mean lordosis duration and decreasing the number of lordosis episodes in the first 5 min of the testing period. These data indicate that serotonin may act in the MPOA-AH via 5-HT(1a/7) receptors to attenuate and 5-HT(2) receptors to facilitate sexual receptivity.     

Monitoring of spine curvatures and posture during pregnancy using surface topography – case study and suggestion of method

Background

Low back and pelvic pain is one of the most frequently reported disorders in pregnancy, however etiology and pathology of this problem have not been fully determined. The relationship between back pain experienced during pregnancy and posture remains unclear. It is challenging to measure reliably postural and spinal changes at the time of pregnancy, since most imaging studies cannot be used due to the radiation burden. 3D shape measurement, or surface topography (ST), systems designed for posture evaluation could potentially fill this void. A pilot study was conducted to test the potential of monitoring the change of spine curvatures and posture during pregnancy using surface topography. A single case was studied to test the methodology and preliminarily assess the usefulness of the procedure before performing a randomized trial. The apparatus used in this study was metrologically tested and utilized earlier in scoliosis screening.

Case presentation

The subject was measured using a custom-made structured light illumination scanner with accuracy of 0.2 mm. Measurement was taken every 2 weeks, between 17th and 37th week of pregnancy, 11 measurements in total. From the measurement the thoracic kyphosis and lumbar lordosis angles, and vertical balance angle were extracted automatically. Custom-written software was used for analysis. Oswestry Low Back Pain Disability Questionnaire (ODI) was done with every measurement. The values were correctly extracted from the measurement. The results were: 50.9 ± 2.4° for kyphosis angle, 58.1 ± 2.1° for lordosis angle and 4.7 ± 1.7° for vertical balance angle. The registered change was 7.4° in kyphosis angle, 8.4° in lordosis angle and 5.5° in vertical balance angle. The calculated ODI values were between moderate disability and severe disability (22 to 58 %).

Conclusions

This case study presents that surface topography may be suitable for monitoring of spinal curvature and posture change in pregnant women. The ionizing radiation studies are contraindicated during pregnancy. Surface topography data connected with information from pain level questionnaires allows to investigate the connection between changes in posture and back pain.

     

Brief Communication: Lumbar lordosis in extinct hominins: Implications of the pelvic incidence

Recently, interest has peaked regarding the posture of extinct hominins. Here, we present a new method of reconstructing lordosis angles of extinct hominin specimens based on pelvic morphology, more specifically the orientation of the sacrum in relation to the acetabulum (pelvic incidence). Two regression models based on the correlation between pelvic incidence and lordosis angle in living hominoids have been developed. The mean values of the calculated lordosis angles based on these models are 36°?45° for australopithecines, 45°?47° for Homo erectus, 27°?34° for the Neandertals and the Sima de los Huesos hominins, and 49°?51° for fossil H. sapiens. The newly calculated lordosis values are consistent with previously published values of extinct hominins (Been et al.: Am J Phys Anthropol 147 (2012) 64–77). If the mean values of the present nonhuman hominoids are representative of the pelvic and lumbar morphology of the last common ancestor between humans and nonhuman hominoids, then both pelvic incidence and lordosis angle dramatically increased during hominin evolution from 27° ± 5 to 22° ± 3 (respectively) in nonhuman hominoids to 54° ± 10 and 51° ± 11 in modern humans. This change to a more human‐like configuration appeared early in the hominin evolution as the pelvis and spines of both australopithecines and H. erectus show a higher pelvic incidence and lordosis angle than nonhuman hominoids. The Sima de los Huesos hominins and Neandertals show a derived configuration with a low pelvic incidence and lordosis angle. Am J Phys Anthropol 154:307–314, 2014. © 2014 Wiley Periodicals, Inc.     

Evidence that sex chromosome genes affect sexual differentiation of female sexual behavior

Female receptivity including the immobile hormone-dependent lordosis posture is essential for successful reproduction in rodents. It is well documented that lordosis is organized during the perinatal period when the actions of androgens decrease the males' ability to display this behavior in adulthood. Conversely the absence of androgens, and the presence of low levels of prepubertal estrogens, preserve circuitry that regulates this behavior in females. The current study set out to determine whether sex chromosomal genes are involved in the differentiation of this behavior. An agonadal mouse model was used to test this hypothesis. The SF-1 gene (Nr5a1) is required for development of gonads and adrenal glands, and knockout mice are consequently not exposed to endogenous gonadal steroids. Thus contributions of sex chromosome genes can be disassociated from the actions of estrogens. Use of this model reveals a direct genetic contribution from sex chromosomes in the display of lordosis and other female-typical sexual behavior patterns. It is likely that the concentrations of gonadal steroids present during normal male development modify the actions of sex chromosome genes on the potential to display female sexual behavior.     

How do we stand? Variations during repeated standing phases of asymptomatic subjects and low back pain patients

An irreproducible standing posture can lead to mis-interpretation of radiological measurements, wrong diagnoses and possibly unnecessary treatment. This study aimed to evaluate the differences in lumbar lordosis and sacrum orientation in six repetitive upright standing postures of 353 asymptomatic subjects (including 332 non-athletes and 21 athletes – soccer players) and 83 low back pain (LBP) patients using a non-invasive back-shape measurement device.In the standing position, all investigated cohorts displayed a large inter-subject variability in sacrum orientation (∼40°) and lumbar lordosis (∼53°). In the asymptomatic cohort (non-athletes), 51% of the subjects showed variations in lumbar lordosis of 10–20% in six repeated standing phases and 29% showed variations of even more than 20%. In the sacrum orientation, 53% of all asymptomatic subjects revealed variations of >20% and 31% of even more than 30%.It can be concluded that standing is highly individual and poorly reproducible. The reproducibility was independent of age, gender, body height and weight. LBP patients and athletes showed a similar variability as the asymptomatic cohort. The number of standing phases performed showed no positive effect on the reproducibility. Therefore, the variability in standing is not predictable but random, and thus does not reflect an individual specific behavioral pattern which can be reduced, for example, by repeated standing phases.     

Lumbar lordosis of extinct hominins

The lordotic curvature of the lumbar spine (lumbar lordosis) in humans is a critical component in the ability to achieve upright posture and bipedal gait. Only general estimates of the lordotic angle (LA) of extinct hominins are currently available, most of which are based on the wedging of the vertebral bodies. Recently, a new method for calculating the LA in skeletal material has become available. This method is based on the relationship between the lordotic curvature and the orientation of the inferior articular processes relative to vertebral bodies in the lumbar spines of living primates. Using this relationship, we developed new regression models in order to calculate the LAs in hominins. The new models are based on primate group-means and were used to calculate the LAs in the spines of eight extinct hominins. The results were also compared with the LAs of modern humans and modern nonhuman apes. The lordotic angles of australopithecines (41° ± 4), H. erectus (45°) and fossil H. sapiens (54° ± 14) are similar to those of modern humans (51° ± 11). This analysis confirms the assumption that human-like lordotic curvature was a morphological change that took place during the acquisition of erect posture and bipedalism as the habitual form of locomotion. Neandertals have smaller lordotic angles (LA = 29° ± 4) than modern humans, but higher angles than nonhuman apes (22° ± 3). This suggests possible subtle differences in Neandertal posture and locomotion from that of modern humans.     

A methodology for quantifying seated lumbar curvatures

To understand the role seating plays in the support of posture and spinal articulation, it is necessary to study the interface between a human and the seat. However, a method to quantify lumbar curvature in commercially available unmodified seats does not currently exist. This work sought to determine if the lumbar curvature for normal ranges of seated posture could be documented by using body landmarks located on the anterior portion of the body. The development of such a methodology will allow researchers to evaluate spinal articulation of a seated subject while in standard, commercially available seats and chairs. Anterior measurements of boney landmarks were used to quantify the relative positions of the ribcage and pelvis while simultaneous posterior measurements were made of lumbar curvature. The relationship between the anterior and the posterior measures was compared. The predictive capacity of this approach was evaluated by determining linear and second-order regressions for each of the four postures across all subjects and conducting a leave-one-out cross validation. The relationships between the anterior and posterior measures were approximated by linear and second-order polynomial regressions (r(2?) = 0.829, 0.935 respectively) across all postures. The quantitative analysis showed that openness had a significant relationship with lumbar curvature, and a first-order regression was superior to a second-order regression. Average standard errors in the prediction were 5.9° for the maximum kyphotic posture, 9.9° for the comfortable posture, 12.8° for the straight and tall, and 22.2° for the maximum lordotic posture. These results show predictions of lumbar curvature are possible in seated postures by using a motion capture system and anterior measures. This method of lumbar curvature prediction shows potential for use in the assessment of seated spinal curvatures and the corresponding design of seating to accommodate those curvatures; however, additional inputs will be necessary to better predict the postures as lordosis is increased.     

Differences on spinal curvature in standing position by gender, age and weight status using a noninvasive method

This aim was to examine differences on lumbar lordosis and thoracic kyphosis in standing position by gender, age and weight status in healthy subjects using a noninvasive method. A total of 297 women (36.6 ± 7.3 years) and 362 men (39.8 ± 7.5 years) participated in this study. Participants were categorized according to the international BMI (kg/m2) cut-off points. Age was stratified by ten years increments starting from 20 y. Men showed smaller lumbar lordosis (17.3 ± 9.3) and larger thoracic kyphosis (42.8 ± 8.8°) than women (29.6 ± 11.3 and 40.4 ± 9.5° respectively; both p < .001). Older groups presented smaller lumbar lordosis and larger thoracic kyphosis values compared with the 20-29 y group (20.9 ± 10.4, 20.8 ± 11.2 and 23.6 ± 12.6° for ≥ 50, 40-49 and 30-39 y, respectively vs. 26.7 ± 12.2° for 20-29 y in lumbar lordosis and 42.6 ± 9.8, 42.61 ± 8.7 and 41.8 ± 8.9° for ≥ 50, 40-49 and 30-39 y, respectively vs. 37.5 ± 10.9° for 20-29 y in thoracic kyphosis; both p < .05). Finally, overweight and obese groups showed smaller lumbar lordosis (19.4 ± 11.1 and 20.9 ± 11.8° respectively) and larger thoracic kyphosis values (42.7 ± 8.9 and 42.8 ± 9.4° respectively) compared with nonoverweight participants (25.1 ± 12.4 and 40.6 ± 9.2° for lumbar lordosis and thoracic kyphosis respectively; all p < .05). However, when gender, age and weight status were take into account all together only gender seems to influence the lumbar lordosis curvature. The results of this study suggest that gender could be the only determinant factor of lumbar lordosis in healthy people.     

Sexual behaviour of female rats subjected to early protein energy malnutrition

Young rats (left with the mother until weaned) were exposed from birth to the age of 49 days to a low protein (malnutritional) diet. At 80 days the young females were ovariectomized and were subjected to standard long-term treatment with oestradiol and progesterone. The females' sexual behaviour was studied in interaction tests with an intact male. It was evaluated according to a scale of sexual responsiveness comprising copulatory (a lordosis posture) and precopulatory (a presenting posture, hopping, ritualized darting) patterns. All the experimental females displayed a high copulatory readiness and precopulatory behaviour; a tendency to lower sexual responsiveness, interpreted as diminished sensitivity to the given doses of the hormones, was manifested only after their repeated administration. Compared with the control females, the number of experimental animals in which the given doses of the hormones induced complete precopulatory behaviour--ritualized darting--was smaller. The results contrast with findings on the sexual behaviour of males subjected to malnutrition from an early age.     

Independence of progesterone-induced facilitation and inhibition of lordosis behavior in ovariectomized guinea pigs

In ovariectomized Hartley guinea pigs, 15 μg progesterone was shown to facilitate lordosis in 48% of animals when administered 36 hr after a 3.3 μg injection of estradiol benzoate. This dose of progesterone also inhibited lordosis behavior in 65% of animals administered an additional 0.6 mg progesterone at 60 hr. Significant inhibition of lordosis response to the 0.6 mg progesterone existed among animals in which lordosis was not facilitated by the initial 15 μg dose of progesterone. These results show that progesterone-induced inhibition can occur without prior facilitation of lordosis as tested by the manual stimulation technique.     

Facilitation of lordosis in guinea pigs by an alpha-noradrenergic agonist is independent of progestin receptor stimulation

Because manipulations of the noradrenergic system affect both lordosis behavior and progestin receptor levels in female guinea pigs, the present study attempted to determine if the noradrenergic (NE) system affects lordosis solely because of its impact on progestin receptors. Although the progestin receptor antagonist RU486 significantly reduced progesterone-facilitated lordosis, it had no effect on lordosis induced by the alpha-NE agonist clonidine in estrogen-primed female guinea pigs. This indicates that although progesterone may facilitate lordosis in female guinea pigs via activation of progestin receptors, the alpha-noradrenergic agonist clonidine does not mediate lordosis through the same mechanism.     

Anti-estrogenic suppression of the lordosis response in female rats

The anti-estrogen, CI 628, was used to suppress the lordosis response induced by sequential injections of estrogen and progesterone in ovariectomized (OVX) female rats. Appropriate doses of CI 628 completely abolished sexual receptivity in females administered estradiol benzoate (EB) in sesame oil. This behavioral effect could be attenuated by providing increased quantities of EB or decreased quantities of CI 628. Anti-estrogenic effects on lordosis induced by free estradiol in saline (E) were assessed after first establishing behaviorally equivalent doses of EB and E. This was accomplished by determining thresholds for E-induced lordosis. OVX females were approximately seven times less sensitive to E than to EB. CI 628 had no significant effects on E-induced lordosis, in contrast to the complete abolition of lordosis in females treated with behaviorally equivalent EB doses. A possible mechanism to explain this differential responsiveness of EB- and E-treated females is discussed.     

Propagation of handclasp grooming among captive chimpanzees

A grooming posture previously reported for two wild chimpanzee (Pan troglodytes) communities developed spontaneously in a captive group of the same species. This offered a unique opportunity to follow the propagation of a new social custom. The posture consists of two partners grasping hands—either both right hands or both left hands—and raising the arms in an A-frame above their heads while mutually grooming with their free hands. The propagation of this pattern was followed over a 5 year period. In the beginning, handclasps were always initiated by the same adult female. This female initiated the posture mainly with her adult female kin. In subsequent years, these relatives became frequent participants in the posture with each other as well as with nonrelatives. Over the years the posture increased in frequency and duration and spread to the majority of adults and also to a few adolescents and older juveniles. The pattern persisted after removal of the apparent originator. Am. J. Primatol. 43:339–346, 1997. © 1997 Wiley-Liss, Inc.     

Changes in the lumbosacral angle, sacral inclination and the curvature of the lumbar spine during aging.

Measurements of the curvature of the lumbar spine are useful in the investigations of low back pain. It is unclear whether the degree of lumbar lordosis, sacral inclination and lumbosacral angulation are the same for all normal adults. Radiographic studies were carried out on the lumbar spines of subjects aged 9-61 years. Mean and 95% tolerance ranges of the values of lumbar lordosis, lumbosacral angle and sacral inclination for adult age groups up to the sixth decade are given. The results showed that all three parameters varied steadily with age. The pattern of changes differed in males and females. Females had greater angles than males. Sacral inclination appeared to be a more important determinant of the degree of lumbar lordosis. All three parameters showed a tendency to decrease after the sixth decade. The significance of the findings is discussed.     

Between-session reliability of opto-electronic motion capture in measuring sagittal posture and 3-D ranges of motion of the thoracolumbar spine

This study evaluated between-session reliability of opto-electronic motion capture to measure trunk posture and three-dimensional ranges of motion (ROM). Nineteen healthy participants aged 24–74 years underwent spine curvature, pelvic tilt and trunk ROM measurements on two separate occasions. Rigid four-marker clusters were attached to the skin overlying seven spinous processes, plus single markers on pelvis landmarks. Rigid body rotations of spine marker clusters were calculated to determine neutral posture and ROM in flexion, extension, total lateral bending (left-right) and total axial rotation (left-right). Segmental spine ROM values were in line with previous reports using opto-electronic motion capture. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were calculated as measures of between-session reliability and measurement error, respectively. Retroreflective markers showed fair to excellent between-session reliability to measure thoracic kyphosis, lumbar lordosis, and pelvic tilt (ICC = 0.82, 0.63, and 0.54, respectively). Thoracic and lumbar segments showed highest reliabilities in total axial rotation (ICC = 0.78) and flexion-extension (ICC = 0.77–0.79) ROM, respectively. Pelvic segment showed highest ICC values in flexion (ICC = 0.78) and total axial rotation (ICC = 0.81) trials. Furthermore, it was estimated that four or fewer repeated trials would provide good reliability for key ROM outcomes, including lumbar flexion, thoracic and lumbar lateral bending, and thoracic axial rotation. This demonstration of reliability is a necessary precursor to quantifying spine kinematics in clinical studies, including assessing changes due to clinical treatment or disease progression.     

Intersex differences in craniocervical morphology and posture in southern Chinese and British Caucasians

The aim of this study was to compare intersex differences in the angular relationships of the head, the cervical column, and the true vertical in natural head posture (the "postural variables") for unselected samples of southern Chinese (n = 240) and British Caucasian (n = 80) 12-year-old children in Hong Kong. For both samples the cervical spine was angulated significantly more forwardly in the females (P less than or equal to 0.001) and the head held higher relative to the spine. Cervical lordosis was also greater in the females and the cervical column of greater relative length. Our findings are in agreement with comparable data previously reported for a northern Finnish population.     

Stepwise reduction of functional spinal structures increase range of motion and change lordosis angle

Many investigators have performed studies on specific defect situations or determined the contribution on isolated structures. Investigating the contribution of functional structures requires obtaining the kinematic response directly on spinal segments. The purpose of this study was to quantify the function of anatomical components on lumbar segments for different loading magnitudes. Eight spinal segments (L4-5) with a median age of 52 years (ranging from 38 to 59 years) and a low degree of disc degeneration were utilized for the in vitro testing. Specimens were mounted in a custom-built spine tester and loaded with pure moments (1-10 N m) to move within three anatomical planes at a loading rate of 1.0 degrees /s. Anatomy was successively reduced by: ligaments, facet capsules, joints and nucleus. Data were evaluated for range of motion, neutral zone and lordosis angle. Transection of posterior ligaments predominantly increased specimen flexion for all bending moments applied. Supraspinous ligament also indicated to resist in extension slightly, whereas the facet capsules did not. Facet joints contributed to axial rotation, but not in lateral bending. The anterior longitudinal ligament was found to slightly resist in axial rotation, but strongly in extension. Nucleotomy caused largest increase of all movements. The unloaded posture of the specimens changed after ligament dissection, indicating ligament pretension. The region of lumbar spine is interesting for finite element (FE) simulation due to the high evidence of disc degeneration and injuries. This study may help to understand the function of specific anatomical structures and assists in FE model calibration. We suggest to start a calibration procedure for such models with the smallest functional structure (annulus) and to cumulatively add further structures.     

Effects of serotonin agonists on lordosis,myoclonus, and cytoplasmic progestin receptors in guinea pigs

Peripheral treatment with the serotonin releaser fenfluramine or the serotonin agonist quipazine abolished lordosis behavior in ovariectomized estradiol and progesterone-primed female guinea pigs. Quipazine was also effective when administered into a lateral cerebroventricle. The lowest dose of fenfluramine that induced myoclonus (10 mg/kg) was higher than the dose needed to inhibit lordosis (5 mg/kg). Therefore, it appears that myoclonus and lordosis are differentially sensitive to serotonin agonists. The effects of quipazine on lordosis were time dependent. Quipazine had no effect on lordosis when given prior to the onset of sexual receptivity. These data suggest that serotonin agonists might be effective only when progesterone has had sufficient time to induce sexual receptivity. Quipazine did not affect cytoplasmic progestin receptors in brain areas involved in steroid hormone effects on lordosis. This finding, and the finding that quipazine had no effect on lordosis when given prior to the onset of sexual receptivity, suggest increased serotonin transmission does not interfere with estrogen priming or sensitivity of hypothalamic cells to progesterone.