Use of self-organizing maps to study sex- and speed-dependent changes in running biomechanics

BackgroundUp to 79% of runners get injured every year, with higher rates of injuries occurring in females than males. A self-organizing map (SOM) is a type of artificial neural network that can be used to inspect large datasets and study coordination patterns. The purpose of this study was to use an SOM to study the effects of sex and speed on biomechanical coordination patterns.MethodThirty-two healthy runners ran on an instrumented treadmill at their long slow distance speed (LSD) and at speed 30% faster (LSD + 30%). Vertical ground reaction force (vGRF), vertical tibial acceleration, step parameters, electromyograms (EMG) of six lower limb muscles, and joint angles were collected across speeds. Rate of loading (ROL), tibial impact shock (TIS), coupling angle variability (CAV) and movement pattern proportions for hip/knee sagittal and hip frontal / knee sagittal plane couplings, peak EMG, step length, step rate, and knee and ankle joint angle at initial contact were used as an input for the SOM (37 variables).ResultsThe analysis identified four clusters (i.e., running patterns). While males and females showed similar distribution across clusters at LSD (p = .36) and at LSD + 30% (p = .51), females did exhibit a significant (p = .03) shift between clusters as the speed increased from LSD to LSD + 30% whereas males did not (p = .17). The shift was associated with an increase in TIS, ROL, step length, step rate, vastus lateralis EMG, hip flexion/knee extension movement pattern proportion, and a decrease in ST EMG and CAV_IC for hip sagittal/knee sagittal coupling.ConclusionAs running speed increased there was a significant change in the coordination pattern in females, which was characterized by increases in several variables that are purported risk factors for running related injuries.     

Single leg landing movement differences between male and female badminton players after overhead stroke in the backhand-side court

Females showed higher anterior cruciate ligament (ACL) injuries rate on the opposite side of dominant hand compared with males during single leg landing in the backhand-side court after overhead stroke. The purpose of this study was to conduct biomechanics testing including kinematics and kinetics to provide some insights on the ACL injuries risks during single leg landing in the backhand-side court after overhead stroke between females and males. Twenty collegiate badminton players (10 females, 10 males) voluntarily participated in this study. Sagittal plane kinematic and kinetic data of the lower limb, and their ground reaction forces during the single leg landing in the backhand-side court after overhead stroke were collected. Results shown that, at the peak posterior ground reaction force (GRF) moment, the ankle dorsiflexion, knee and hip flexion angles of the female were lower than that of male. Meantime, the knee extension moment of the female was lower than that of males but the hip extension moment of the female was larger compared to males at the peak posterior GRF moment. The peak vertical and posterior GRF of female badminton players were larger than that of males. Decreased hip, knee, and ankle flexion angles at the peak posterior GRF moment and greater peak vertical and posterior GRF may expose female badminton players to the higher risk ACL injuries compared to males during single leg landing after overhead stroke in the backcourt-side. Preventative training programs designed to prevent the ACL injuries rate of female badminton players should take these factors into consideration.     

How does normal variability in trunk flexion affect lower limb muscle activity during walking?

A large proportion of the mass of the body is contained within the trunk segment. Therefore, small changes in the inclination of this segment have the potential to influence the direction of the ground reaction force and alter lower limb joint moments and muscle activation patterns during walking. The aim of this study was to investigate if variability in sagittal trunk inclination in healthy participants is associated with differences in lower limb biomechanics. Gait analysis data was collected on 41 healthy participants during walking. Two groups were defined based on habitual trunk flexion angle during normal walking, a forward lean group (n = 18) and a backward lean group (n = 17). Lower limb moments, muscle activation patterns and co-contraction levels were compared between the two groups using independent t-tests. The forward lean group walked with 5° more trunk flexion than the backward lean group. This difference was associated with a larger peak hip moment (effect size = 0.7) and higher activation of the lateral gastrocnemius (effect size =0.6) and the biceps femoris (effect size =0.7) muscles. The forward lean group also exhibited greater co-contraction in late stance (effect size =0.7). This is the first study to demonstrate that small differences in trunk flexion are associated with pronounced alterations in the activation of the lateral knee flexor muscles. This is important because people with knee osteoarthritis have been observed to walk with increased trunk flexion. It is possible that increased sagittal trunk inclination may be associated with elevated joint loads in people with knee osteoarthritis.     

Focus of attention effects on lower extremity biomechanics during vertical jump landings

This study examined biomechanical differences between external and internal foci of attention during vertical jump landings in males and females. Twenty-four healthy adults performed eight vertical jump landings using both internal and external foci while three-dimensional kinematic and ground reaction force (GRF) data were obtained. Two (focus) by two (sex) analyses of variance (α = 0.05) and Cohen's d effect sizes (ES) were used to compare differences in vertical GRF, joint angular positions and displacements, and lower limb joint angular work between foci and between sexes. Significantly greater knee contributions to total angular work occurred during external versus internal focus landings regardless of sex (p = .013; ES = 0.30). Significantly smaller plantarflexion angles (p = .019; ES = 0.53) and significantly greater knee flexion angles were observed at ground contact (p < .001; ES = 1.11) in males during external focus landings. Females exhibited significantly smaller knee flexion angles at both ground contact during external versus internal focus landings (p = .031; ES = 0.20) and compared to males during external focus landings (p < .001; ES = 1.76). Both peak vertical GRF (p = .003; ES = 1.54) and the ankle contributions to total angular work during loading (p = .026; ES = 1.07) were greater in females versus males regardless of foci, whereas the knee contributions to total angular work during loading were smaller in women (p = .026; ES = 1.07). Males and females might consider adopting an external focus during vertical jump landings to increase knee joint contributions to lower limb energy absorption. Females, in particular, might consider external focus use to decrease peak vertical GRF and increase the knee joint's contribution to total energy absorption to magnitudes similar to those exhibited by males.     

Position of the non-stance leg during the single leg squat affects females and males differently

BackgroundKinematic differences between females and males for the single leg squat (SLS) have been identified. However, kinetic differences between sexes and how variations of the non-stance leg position during the SLS may affect kinematics and kinetics differently in females and males have not been examined.ObjectivesExamine sex-specific kinematic and kinetic differences during the SLS task with 3 different non-stance leg positions.DesignControlled laboratory study, cross-sectional design.MethodsThirty-two healthy adults (16 females, 16 males) performed the 3 SLS tasks while data were collected using a motion capture system and force plates. At 60 degrees of knee flexion (60KF) and peak knee flexion (PKF), kinematics and joint moments were compared between sexes and SLS tasks using a linear regression analysis.ResultsFemales exhibited less ipsilateral trunk flexion (P < 0.001) and greater anterior pelvic tilt (P ≤ 0.021) and hip adduction (P < 0.001) than males across tasks at 60KF and PKF. Across tasks, females had a smaller knee flexion moment than males at PKF (P = 0.001). Females had a greater hip abduction moment during SLS-Front than SLS-Middle (P = 0.044) and SLS-Back (P = 0.003) at PKF, but males had similar hip abduction moments across tasks (P ≥ 0.299). At 60KF, males had a greater knee adduction moment during SLS-Front compared to the other tasks (P ≤ 0.019) while females had similar hip abduction moments across tasks (P ≥ 0.459).ConclusionAltering the non-stance leg position during the SLS affects the kinematics and kinetics of both females and males. The position of the non-stance leg can be modified for assessment and treatment purposes and should be reported in research.     

Authoritarianism and the EPQ

Investigated the personality correlates of authoritarian attitudes (Ray, 1979) and anti-submissive behaviour (Rigby, 1986), among an Australian college sample (N = 198). Authoritarianism (in the attitudinal sense) was found not to correlate with the major dimensions of the EPQ for the whole sample although female authoritarians scored high on the N subscale (r = 0.40; P < 0.01). By contrast, anti-submissive behaviour was found to be associated with extraversion for females and tough-mindedness for males. Further factor analysis revealed the P subscale of the EPQ not to load on a factor identified as ‘authoritarianism’. This does not support the research of Kline and Cooper (1984).     

Egyptian results on the standard progressive matrices

Specific psychometric parameters of the Standard Progressive Matrices (SPM) for Egyptian undergraduate 205 males and 247 females were investigated. The 1 wk retest reliability was 0.82 (n = 44). A clear and high loaded factor was extracted from the 5 sets, indicating high internal consistency. The factor analysis of the SPM total score and 4 subtests of Thurstone's Primary Mental Abilities, that is, verbal comprehension, number, space, and inductive reasoning, yielded a general and high loaded factor, on which the SPM saturation is 0.77. This denotes significant and high concurrent validity. The mean score of Egyptian males was quite similar to that of British males, however, the mean score for the females was somewhat low. It is concluded that the SPM is a viable tool in the Egyptian context.     

Exposure to Remittances: Theoretical and Empirical Implications for Gender

Exposure to remittance, or the benefits of remittances, is a new concept introduced to the scholarship of migration studies, and within this broad concept there are also important gender dimensions. Women constitute around half of the total international migration flow in today’s world; however, the amount of the remittance that they are exposed to is considerably lower than that of males. This paper argues that although females remit a higher proportion of their income than men, they enjoy less ‘exposure to remittance’ than men. One hundred one respondents (remitters and receivers) were interviewed using an open and closed ended questionnaire from seven selected countries in Asia. Conceptualization of ‘exposure to remittance’ has been made with empirical support. The level of exposure depends on a respective country’s social and cultural milieu. Females in Bangladesh (P?<?0.004) are significantly less exposed to remittances than those of the Philippines, Sri Lanka and Thailand.     

Technique determinants of knee joint loads during cutting in female soccer players

The aim of this study was to investigate the relationships between technique characteristics and knee abduction moments during 90° cuts. A cross sectional design involving 26 elite and sub-elite female soccer players (mean ± SD; age: 21 ± 3.2 years, height: 1.68 ± 0.07 m, and mass: 59.1 ± 6.8 kg) was used to explore relationships between pre-determined technical factors on knee abduction moments during cutting. Three dimensional motion analyses of 90° cuts on the right leg were performed using ‘Qualisys Pro Reflex’ infrared cameras (240 Hz). Ground reaction forces were collected from two AMTI force platforms (1200 Hz) embedded into the running track to examine 2nd last and last footfalls. Pearson’s correlation coefficients, co-efficients of determination and hierarchical multiple regression were used to explore relationships between a range of technique parameters and peak knee abduction moments. Significance was set at p < .05. Hierarchical multiple regression revealed that initial knee abduction angle, lateral leg plant distance and initial lateral trunk lean could explain 67% (62% adjusted) of the variation in peak knee abduction moments (F_(1,22) = 8.869, p = .007). These findings reveal potential modifiable technical factors to lower peak knee abduction moments during cutting.     

Dynamics of the ankle joint analyzed through moment-angle loops during human walking: gender and age effects

Aim of this study was to provide a non-invasive assessment of the dynamic properties of the ankle joint during human locomotion, with specific focus on the effects of gender and age. Accordingly, flexion-extension angles and moments, obtained through gait analysis, were used to generate moment–angle loops at the ankle joint in 120 healthy subjects walking at a same normalized speed. Four reproducible types of loops were identified: Typical Loops, Narrow, Large and Yielding loops. No significant changes in the slopes of the main loop phases were observed as a function of gender and age, with the exception of a relative increase in the slope of the descending phase in elderly males compared to adult females. As for the ergometric parameters, the peak ankle moment, work produced and net work along the cycle were slightly, but significantly affected, with progressively decrease in the following order: Adult Males, Adult Females, Elderly Males and Elderly Females. The evidence that only few of the quantitative aspects of moment–angle loops were affected suggests that the control strategy which regulates the biomechanical properties of the ankle joint during walking is rather robust and qualitatively consistent across genders and age.     

Social desirability and relations between goal orientations and competitive trait anxiety in young athletes

ObjectivesTo examine the impact of a social desirability response set on relations between goal orientation and performance anxiety in youth sports.DesignCorrelational field design.MethodData assessing goal orientation, performance anxiety, and social desirability were obtained from male (n=106) and female (n=75) adolescent athletes (M age=12.1 years; SD=1.3 years).ResultsFemale athletes reported significantly higher levels of task orientation and lower levels of ego orientation and concentration disruption, than males. As predicted, ego orientation was positively correlated with all indices of performance anxiety in males and females. Task orientation was negatively associated with all indices of performance anxiety in males but only concentration disruption in females. Social desirability was negatively related to ego orientation in males and females, and positively related to task orientation in females, but not males. Performance anxiety was negatively related to social desirability in females, but not males. Controlling for social desirability attenuated the observed relations between goal orientations and performance anxiety in females, but not males.ConclusionsThese results suggest the importance of incorporating measures of social desirability when studying psychosocial variables with either positive or negative connotations. Our results suggest that social desirability may contribute to relations between goal orientation and anxiety in athletes, particularly females.     

A biometrical study of schizotypy in a normal population

A recently devised two-scale questionnaire (STQ) for measuring ‘borderline’ personality traits, together with the EPQ, was administered to 108 monozygotic and 102 dizygotic adult twin pairs. Initial item and scale analyses of the STQ indicated good internal consistency and acceptably high endorsement frequencies for individual items, as well as an absense of any marked skew in the scale distributions. The pattern of correlations with the EPQ closely resembled that seen in earlier, smaller-sized studies, the most notable feature being a positive correlation between the borderline scales and the N-scale. Biometrical analysis of the data suggested that, for the main STQ scale (‘schizotypal personality’), the best-fitting model was one assuming additive genetic variation combined with within-family environmental effects: results for the other (‘borderline personality’) scale were less clear cut. A number of sex differences were also observed: males had lower schizotypy scores than females, while the biometrical analysis suggested that schizotypy may be under greater genetic control in males than in females. The data are presented and discussed in the context of the dimensional/biological theory of disposition to psychosis.     

Anthropometric characteristics and gait transition speed in human locomotion

The purpose of this study was to investigate the relationship between anthropometric parameters and the preferred transition speed (PTS) in human locomotion, in both genders. Previous studies exploring body measures as possible determinants of the PTS were biased toward longitudinal body dimensions, while the relationship between the PTS and transverse body dimensions has so far not been examined. Longitudinal and transverse anthropometric parameters were measured in 48 physical education students (21 males, 27 females), and an exercise test was performed for determination of the PTS. The relationship between the PTS and the anthropometric variables was determined using Pearson product-moment correlations and stepwise multiple regression analysis. Weak to moderate correlations between several body size and body shape variables and the PTS were found. In males, significant negative correlations (p<.05) between transverse body dimensions scaled to body height (calf girth, shoulder, bicristal and bitrochanteric diameters) and the PTS were found (r=-.51 to -.63). In females, calf girth and thigh girth scaled to height were significantly negatively correlated with the PTS (r=-.61 and -.42, respectively; p<.05). The results of the study suggest that gait transition speed in humans is related to both transverse and longitudinal body dimensions, and that sexual dimorphism in body size and shape should be taken into consideration for a proper interpretation of the PTS.     

Maternal employment,anxiety, and sex differences in college students' self-descriptions

This study sought to determine if a relationship exists between maternal employment during childhood, anxiety, and gender in college students. A questionnaire incorporating the Adjective Generation Technique (AGT) was administered to undergraduate psychology students from intact, two-parent families. Subjects were grouped into four categories: males whose mothers worked during their childhood (n=33), males whose mothers remained home (n=49), females whose mothers worked (n=54), and females whose mothers remained home (n=49). Data were analyzed using a 2×2 analysis of variance. Results indicated no differences in anxiety for subjects of either sex in relationship to the employment status of the mothers. A pronounced sex difference was found, with females scoring significantly higher in anxiety than males.     

On the biological determination of personality structure

The controversy surrounding two particular problems has stymied the development of a consensus view concerning the structure of personality. First, there has been disagreement concerning the ‘independence’ of introversion-extraversion and measures of neuroticism. The other problem concerns the ‘duality’ of introversion-extraversion and whether it is even useful to retain this concept when it may only represent a ‘shotgun wedding’ of ‘sociability’ and ‘impulsivity’. Recent findings are discussed which relate to the neurophysiological underpinnings of personality. It is suggested that these findings, and the associated model, lie outside the circulus vitiosus of factor analysis and therefore that they provide a basis for resolving the independence and duality issues. It is argued that the tendency for introversion-extraversion to correlate with neuroticism only reflects a degree of coincidence and not equivalence. The psychological coincidence is conceived as resulting from the anatomical linkage of different neurophysiological subsystems which provide the substrata for the two personality dimensions. It is also argued that the ‘sociability’ and ‘impulsivity’ duality relates to distinct ‘sensitivity’ and ‘synergistic’ aspects of thalamocortical arousability. These distinct arousability dimensions nevertheless both contribute to the effectiveness of descending inhibitory projections that act on the brain-stem reticular formation and hence determine introversion-extraversion differences. In this scheme of things the three psychological dimensions are different but again there are anatomical linkage correlations reflecting coincidence rather than equivalence.     

Gender differences in coordination variability between shank and rearfoot during running

Female recreational runners are 2–3 times more likely to suffer from knee injury compared with male runners. However, the exact reason for this gender difference regarding knee injury remains unclear. Our study aimed to investigate gender differences in coordination variability between shank and rearfoot during running using statistical parametric mapping (SPM). Eleven healthy males and eleven healthy females ran on a treadmill. A modified vector coding technique procedure was used to create joint coupling between shank internal/external rotation and rearfoot eversion/inversion. The standard deviation of each coupling was computed as a measure of coordination variability during the stance phase. All trajectory data of coordination variability between genders were analyzed using a two-sample t-test of SPM. No differences in the normalized spatiotemporal parameters of speed, cadence and step length were found between males and females. SPM showed no significant differences between the genders in coordination variability. This study demonstrated that coordination variability between the shank and rearfoot during running may not be associated with the different incidence rates of knee injuries among male and female participants.     

Sex and menstrual cycle differences in the habituation and spontaneous recovery of the electrodermal orienting reaction

Sex and menstrual cycle differences have been widely observed in electrodermal activity. The aim of this study was to investigate these differences in the electrodermal orienting reaction employing a habituation-spontaneous recovery procedure. According to previous research it was predicted that men and preovulatory women should show higher electrodermal responses, higher skin conductance levels, and slower habituation rates. Thirty-two subjects (16 males and 16 females) were presented with two series of tones, 10 in the first series and eight in the second, with a 4-min rest period between the two series. Half of the subjects received the same 5-sec tone (80 dB, 1000 Hz) in each presentation while the other half received 80-dB, 5-sec tones which varied randomly in frequency (100, 500, 1000 Hz). Women were divided into two groups; preovulatory (n = 7) and postovulatory (n = 8) according to their answers to a retrospective questionnaire. The mean response amplitude was higher in the group of males, who habituated later than females. Postovulatory women showed lower orienting reactions in the first series, and habituated faster than did preovulatory women in the two series. There were neither significant differences between males and females, nor between preovulatory and postovulatory women in tonic conductance levels. These results support the existence of greater electrodermal reactivity in males and in preovulatory women.     

What Causes Internalising Traits and Autistic Traits to Co-occur in Adolescence? A Community-Based Twin Study

Autism shows a high degree of comorbidity with anxiety disorders. Adolescence is a time of increased stress and vulnerability to internalising problems. This study addresses for the first time the degree of genetic and environmental overlap between autistic traits (total measure and subscales) and internalising traits in a community-based adolescent twin sample. Parents of 12-14-year-old twins (N?=?3,232 pairs; 3,460 males, 3,004 females) reported on the twins’ internalising and autistic traits. Autistic trait subscales were created using principal component analysis. Bivariate twin model-fitting was conducted. Autistic and internalising traits correlated moderately (r?=?0.30). Genetic influences on individual traits were substantial but genetic overlap between traits was moderate (genetic correlation: males?=?0.30, females?=?0.12). Shared environmental influences were low for internalising traits and moderate for autistic traits, and showed considerable overlap (shared environmental correlation: males?=?0.53, females?=?1). Nonshared environmental influences were moderate for internalising traits and low for autistic traits and showed low overlap. A multiple component solution was found for autistic traits and of the derived subscales, autistic-like ‘Social Unease’ showed the most phenotypic and genetic overlap with internalising traits.     

Working mothers,sex differences,and self-esteem in college students' self-descriptions

This study examined whether a relationship exists between maternal employment and self-esteem of offspring. A questionnaire incorporating the Adjective Generation Technique (AGT) was administered to undergraduate psychology students from intact two-parent families. Subjects were divided into four categories: males whose mothers worked during their childhood (n=33), males whose mothers remained home (n=49), females whose mothers worked (n=54), and females whose mothers remained home (n=49). Data were analyzed using a 2 × 2 analysis of variance. Results indicated no differences in self-esteem for subjects of either sex in conjunction with the employment of their mothers. Instead, the subject's sex was the critical component affecting self-esteem. Males reported themselves significantly more favorably than did females.     

Empirical support for the gender‐as‐culture hypothesis.

This investigation provided a test of the gender‐as‐culture, or ‘two cultures’, hypothesis proposed by Maltz and Borker (1982) to explain male/female differences in language use. Analysis of previous empirical investigations located 16 language features that had consistently been shown to indicate communicator gender and these were tested within the framework of the four dimensions of intercultural style proposed by Gudykunst and Ting‐Toomey (1998): direct versus indirect, succinct versus elaborate, personal versus contextual and instrumental versus affective. Study 1 provided preliminary evidence supporting the hypothesized language‐feature‐by‐dimension relationships (e.g., male directives were rated more direct and female uncertainty verbs more indirect). In Study 2, respondents rated multiple exemplars of the 16 language features, as well as 16 contrasting foil sentences, on all four dimensions, finding that nearly all of the variables fell on the hypothesized intercultural dimensions. In Study 3, respondents rated four sets of naturally occurring target sentences and matching foil sentences, representing all language variables, on their appropriate intercultural dimensions in order to establish dimensional polarity. Results across the three studies supported the hypothesized language feature‐by‐stylistic dimension relationship for 15 of the 16 variables: The 6 male language features were rated as more direct, succinct, personal, and instrumental, whereas 9 of the 10 female features were perceived as more indirect, elaborate, and affective. The findings demonstrate that gender preferences for language use function in ways that are consistent with stylistic preferences that distinguish national cultures.