Transitions between symmetrical and asymmetrical gaits: a biomechanical analysis

INTRODUCTION: Gallop is a skipping gait in which one leg (the leading leg) is continuously kept in front of the other (3). This type of locomotion occurs spontaneously in the development of locomotion in children (1) and occurs sometimes in adults when descending stairs or a slope at high speed (2). Although gallop is a naturally occurring human locomotion pattern, research on human gallop is limited. METHODS: Fifteen female subjects with homogeneous stature were selected. They were asked to walk, run and gallop at preferred speed and to perform multiple transitions from walking to running (WRT), galloping to running (GRT) and walking to galloping (WGT). Subjects were equipped with 59 reflective markers and performed the trials on an overground walkway with 6 built‐in forceplates and 12 infrared cameras (Pro Reflex, Qualisys). Kinematics and kinetics were calculated using commercial software (Visual 3D, C‐motion). RESULTS: Subjects consistently used the same leading leg during gallop. Joint kinematics and kinetics showed differences between the leading and trailing leg in gallop. Transition speed of GRT (3.83±0.34ms‐1) was significantly higher than transition speed of WGT (2.66±0.24ms‐1)(p<0.01) and WRT (2.82±0.26ms‐1)(p<0.01) but no statistical difference was found between WGT and WRT (p=0.410)(fig.1). A clear transition step was seen in the WRT and the GRT based on joint kinematics, kinetics, and patterns of mechanical energy. In the WRT, GRT and WGT the swing phase prior to the transition step showed greater (dorsi)flexion in the ankle, knee and hip in comparison with previous walking/galloping steps. In the WGT (2.66±0.24 ms‐1) also the stance phase in the step before transition showed more (dorsi)flexion in the ankle, knee and hip. When subjects initiated the WGT when the leading leg was not in front, they showed some inconsistent intermediate running/skipping steps before they started galloping. Fig.1: transition speed for WGT, WRT and GRT. *and* are significant differences between transitions (p<0,01) CONCLUSIONS: Gallop is appropriately called an asymmetrical gait pattern as the leading and trailing leg execute a different movement. Adults seldom switch spontaneously from walking to galloping so the WGT is supposed to be planned. Still the initiation of transition seems to occur spontaneously because transition sometimes initiated when the leading leg was not in front. If the transition would occur intentionally, one would expect that transition only initiates when the leading leg is in front. Transition speed is very similar for WGT and WRT so it could be that a similar mechanism (arising in the acceleration from walking) determines when the transition occurs. Transition is prepared in the same way in the WRT and the GRT. There is a limited preparation in the swing phase preceding the actual transition step. In the WGT two transition steps were seen. As both legs carry out a different movement in gallop, it seems like each leg needs a transition step to alter the new gait configuration. The transition from an asymmetrical gait pattern to a symmetrical gait pattern (GRT) seems easier to perform than a transition from a symmetrical gait pattern to an asymmetrical gait pattern (WGT) as at least two steps were necessary to make the transition in the WGT in comparison with one step in the GRT. The gait pattern before the transitions, seems to determine the instant of transition initiation (similarity between WGT and WRT). The gait pattern after transition seems to be important in the way the transition is prepared (similarity between WRT and GRT). REFERENCES 1.Clark JE, Whitall J. Changing patterns of locomotion: from walking to skipping. In: Woollacott M, Shumway‐Cook A, editors. Development of posture and gait across the life span. Columbia: University of South Carolina Press; 1989.p. 128‐51. 2.Getchell N, Whitall J. Transitions to and from asymmetrical gait patterns. Journal of Motor Behaviour. 2004; 36 (1):13‐27. 3.Minetti AE. The biomechanics of skipping gaits: a third locomotion paradigm? Proceedings of the Royal Society B: Biological Sciences. 1998;265:1227‐35

Effectiveness and feasibility of lowering playground density during recess to promote physical activity and decrease sedentary time at primary school

Background: This pilot study aimed at investigating the effectiveness of lowering playground density on increasing children’s physical activity and decreasing sedentary time. Also the feasibility of this intervention was tested. Methods: Data were collected in September and October 2012 in three Belgian schools in 187, 9–12 year old children. During the intervention, playground density was decreased by splitting up recesses and decreasing the number of children sharing the playground. A within-subject design was used. Children wore accelerometers during the study week. Three-level (class – participant - measurement (baseline or intervention)) linear regression models were used to determine intervention effects. After the intervention week the school principals filled out a questionnaire concerning the feasibility of the intervention. Results: The available play space was 12.18 ± 4.19 m2/child at baseline and increased to 24.24 ± 8.51 m2/child during intervention. During the intervention sedentary time decreased (−0.58 min/recess; -3.21%/recess) and moderate-to-vigorous physical activity (+1.04 min/recess; +5.9%/recess) increased during recess and during the entire school day (sedentary time: -3.29%/school day; moderate-to-vigorous physical activity +1.16%/school day). All principals agreed that children enjoyed the intervention; but some difficulties were reported. Conclusions: Lowering playground density can be an effective intervention for decreasing children’s sedentary time and increasing their physical activity levels during recess; especially in least active children

The environment and physical activity

Until recently, obesity research has mainly focused on biological and behavioral factors. However, there is growing agreement among researchers that the social and physical environment may play an important role as well. Certain aspects of the environment may promote or discourage physical activity and therefore have an influence on children’s body weight. The purpose of this chapter is to give an overview of the current knowledge on the relation between the physical neighborhood environment and physical activity in children

Organizing 'Play Streets' during school vacations can increase physical activity and decrease sedentary time in children

A Play Street is a street that is reserved for children’s safe play for a specific period during school vacations. It was hypothesized that a Play Street near children’s home can increase their moderate- to vigorous-intensity physical activity (MVPA) and decrease their sedentary time. Therefore, the aim of this study was to investigate the effect of Play Streets on children’s MVPA and sedentary time. A nonequivalent control group pretest-posttest design was used to determine the effects of Play Streets on children’s MVPA and sedentary time. Data were collected in Ghent during July and August 2013. The study sample consisted of 126 children (54 from Play streets, 72 from control streets). Children wore an accelerometer for 8 consecutive days and their parents fill out a questionnaire before and after the measurement period. During the intervention, streets were enclosed and reserved for children’s play. Four-level (neighborhood – household – child – time of measurement (no intervention or during intervention)) linear regression models were conducted in MLwiN to determine intervention effects. Positive intervention effects were found for sedentary time (β = -0.76 ± 0.39; χ2 = 3.9; p = 0.05) and MVPA (β = 0.82 ± 0.43; χ2 = 3.6; p = 0.06). Between 14h00 and 19h00, MVPA from children living in Play Streets increased from 27 minutes during normal conditions to 36 minutes during the Play Street intervention, whereas control children’s MVPA decreased from 27 to 24 minutes. Sedentary time from children living in the Play Street decreased from 146 minutes during normal conditions to 138 minutes during the Play Street intervention, whereas control children’s sedentary time increased from 156 minutes to 165 minutes. The intervention effects on MVPA (β = -0.62 ± 0.25; χ2 = 6.3; p = 0.01) and sedentary time (β = 0.85 ± 0.0.33; χ2 = 6.6; p = 0.01) remained significant when the effects were investigated during the entire day, indicating that children did not compensate for their increased MVPA and decreased sedentary time, during the rest of the day. Creating a safe play space near urban children’s home by the Play Street intervention is effective in increasing children’s MVPA and decreasing their sedentary time

The association between objective walkability, neighborhood socio-economic status, and physical activity in Belgian children

Background: Objective walkability is an important correlate of adults’ physical activity. Studies investigating the relation between walkability and children’s physical activity are scarce. However, in order to develop effective environmental interventions, a profound investigation of this relation is needed in all age groups. The aim of this study was to investigate the association between objective walkability and different domains of children’s physical activity, and to investigate the moderating effect of neighborhood socio-economic status in this relation. Methods: Data were collected between December 2011 and May 2013 as part of the Belgian Environmental Physical Activity Study in children. Children (9–12 years old; n = 606) were recruited from 18 elementary schools in Ghent (Belgium). Children together with one of their parents completed the Flemish Physical Activity Questionnaire and wore an accelerometer for 7 consecutive days. Children’s neighborhood walkability was calculated using geographical information systems. Multilevel cross-classified modeling was used to determine the relationship between children’s PA and objectively measured walkability and the moderating effect of neighborhood SES in this relation. Results: In low SES neighborhoods walkability was positively related to walking for transportation during leisure time (β = 0.381 ± 0.124; 95% CI = 0.138, 0.624) and was negatively related to sports during leisure time (β = −0.245 ± 0.121; 95% CI = −0.482, −0.008). In high socio-economic status neighborhoods, walkability was unrelated to children’s physical activity. No relations of neighborhood walkability and neighborhood socio-economic status with cycling during leisure time, active commuting to school and objectively measured moderate- to vigorous-intensity physical activity were found. Conclusions: No univocal relation between neighborhood walkability and physical activity was found in 9–12 year old children. Results from international adult studies cannot be generalized to children. There is a need in future research to determine the key environmental correlates of children’s physical activity

The association between the parental perception of the physical neighborhood environment and children's location-specific physical activity

Background: The relationship between children's physical neighborhood environment and their physical activity, has been largely investigated. However in recent reviews, only a few significant and consistent direct associations between children's physical neighborhood environment and their physical activity were found. This is possibly due to the fact that the location where children's physical activity took place, is insufficiently specified. Therefore, this study aimed to investigate the association between parental perceived neighborhood characteristics and children's physical activity in clearly defined environments. Methods: Children (9-12 years; n = 606) wore an Actigraph accelerometer for 7 days. Parents completed the parental version of the Neighborhood Environmental Walkability Scale questionnaire and reported on children's physical activity in specific locations: physical activity in nearby streets and on sidewalks, physical activity in public recreation spaces and physical activity in the garden. Multilevel logistic regression analyses were conducted in MLwiN 2.30. Results: Children were more likely to be active in nearby streets and on sidewalks, if their parents perceived lower street connectivity (OR = 0.479; 95 % CI = 0.33 and 0.70), higher land use mix accessibility (OR = 1.704; 95 % CI = 1.25 and 2.33) and more crime safety (OR = 1.879; 95 % CI = 1.29 and 2.74). Children whose parents perceived higher presence of recreation facilities (OR = 1.618; CI = 1.23; 2.12) were more likely to be active in public recreation spaces. No environmental neighborhood variables were related to physical activity in the garden and overall moderate-to vigorous-intensity physical activity. Conclusions: The parental perceived physical neighborhood environment relates differently to physical activity in different locations. In order to develop effective interventions, it seems promising to further investigate the association between location-specific physical activity and specific neighborhood environmental correlates

The moderating effect of psychosocial factors in the relation between neighborhood walkability and children’s physical activity

BACKGROUND: The study aimed to investigate if psychosocial factors moderate the association between objective walkability and different domains of children's physical activity (PA). A second aim of the study was to investigate the direct associations between psychosocial factors and children's PA. Based on previous literature, it was hypothesized that walkability would be more strongly related to PA among children with negative psychosocial profiles. METHODS: Data were collected between December 2011 and May 2013 as part of the Belgian Environmental Physical Activity Study in children (BEPAS-child). In total, data from 494 children and one of their parents were included in the study. Children wore an accelerometer for 7 consecutive days and together with one of their parents, they completed the Flemish Physical Activity Questionnaire. Parents filled out a questionnaire concerning their child's psychosocial factors toward PA (i.e. parental attitude toward their child's PA, parental social norm toward their child's PA, parental support, friend support, children's self-efficacy, and perceived benefits and barriers toward sports and PA). Neighborhood walkability was calculated using geographical information systems (GIS). Multilevel cross-classified analyses were conducted. RESULTS: Of the 42 investigated interactions between neighborhood walkability and psychosocial factors in relation to PA among children, only 7 significant interactions were found of which 3 were only significant among children from low-income neighborhoods. Parental support and self-efficacy were positive correlates of children's PA in high- and low-income neighborhoods independent of the level of walkability, but effect sizes were small. CONCLUSIONS: The hypothesis that walkability would be more strongly related to PA among children with negative psychosocial profiles could not be confirmed and in general, psychosocial factors and objective walkability did not interact in relation to children's PA. Focusing on parental support and self-efficacy towards PA can possibly cause small effects on children's PA in both high- and low-walkable neighborhoods, as well as in high- and low-income neighborhoods

Cross-continental comparison of the association between the physical environment and active transportation in children : a systematic review

Background: The purpose of this systematic review was to determine the relationship between a wide range of physical environmental characteristics and different contexts of active transportation in 6- to 12-year-old children across different continents. Methods: A systematic search was conducted in six databases (Pubmed, Web of Science, Cinahl, SportDiscus, TRIS and Cochrane) resulting in 65 papers, eligible for inclusion. The investigated physical environmental variables were grouped into six categories: walkability, accessibility, walk/cycle facilities, aesthetics, safety, recreation facilities. Results: The majority of the studies were conducted in North America (n = 35), Europe (n = 17) and Australia (n = 11). Active transportation to school (walking or cycling) was positively associated with walkability. Walking to school was positively associated with walkability, density and accessibility. Evidence for a possible association was found for traffic safety and all forms of active transportation to school. No convincing evidence was found for associations between the physical environment and active transportation during leisure. General safety and traffic safety were associated with active transportation to school in North America and Australia but not associated with active transportation to school in Europe. Conclusions: The physical environment was mainly associated with active transportation to school. Continent specific associations were found, indicating that safety measures were most important in relation to active commuting to school in North America and Australia. There is a need for longitudinal studies and studies conducted in Asia, Africa and South-America and studies focusing specifically on active transportation during leisure

Feasibility and effectiveness of drop-off spots to promote walking to school

Background: Drop-off spots are locations in the proximity of primary schools where parents can drop off or pick up their child. From these drop-off spots children can walk to and from school. This pilot study aimed to investigate the feasibility and effectiveness of drop-off spots and to evaluate how drop-off spots are perceived by school principals, teachers and parents of 6-to-12-year old children. Methods: First, a feasibility questionnaire was completed (n = 216) to obtain parental opinions towards the implementation of drop-off spots. A drop-off spot was organized (500-800 m distance from school) in two primary schools. A within-subject design was used to compare children's (n = 58) step counts and number of walking trips during usual conditions (baseline) and during implementation of a drop-off spot (intervention). Three-level (class-participant- condition) linear regression models were used to determine intervention effects. After the intervention, 2 school principals, 7 teachers and 44 parents filled out a process evaluation questionnaire. Results: Prior to the intervention, 96% expressed the need for adult supervision during the route to school. Positive significant intervention effects were found for step counts before/after school hours (+732 step counts/day; X-2 = 12.2; p < 0.001) and number of walking trips to/from school (+2 trips/week; X-2 = 52.9; p < 0.001). No intervention effect was found for total step counts/day (X-2 = 2.0; p = 0.16). The intervention was positively perceived by the school principals and parents, but teachers expressed doubts regarding future implementation. Conclusion: This pilot study showed that implementing drop-off spots might be an effective intervention to promote children's walking to school. Implementing drop-off spots does not require major efforts from the schools and schools can choose how and when they organize drop-off spots. However, motivating teachers and involving other volunteers (e. g. parents, grandparents) may be needed. Future studies should investigate the feasibility and effectiveness of drop-off spots in a larger sample of schools

Mediating effects of self-efficacy, benefits and barriers on the association between peer and parental factors and physical activity among adolescent girls with a lower educational level

Background : The prevalence of physical activity among lower educated adolescent girls is low, suggesting it is important to have insights into the complex processes that may underlie their physical activity levels. Therefore, this study aimed to examine the mediating effects of self-efficacy, perceived benefits and barriers on the associations between peer and parental variables and physical activity among lower educated adolescent girls. Methods : In total, 226 girls (mean age 16.0 +/- 1.0 years; 53% technical education; 47% vocational education) from a convenience sample of 6 secondary schools in Flanders, Belgium, completed a questionnaire on their total physical activity level and related peer and parental variables (i.e. modeling of physical activity, co-participation in physical activities and encouragement to be active) and personal variables (i.e. self-efficacy to be active, and specific perceived benefits of physical activity and specific barriers to be active). Mediating effects were tested using MacKinnon's product-of-coefficients test based on multilevel linear regression analyses. Results : Higher peer and parental modeling, co-participation and encouragement were significantly related to a higher physical activity level among adolescent girls (p<0.05). Self-efficacy, the perceived benefits of having fun, being around friends or meeting new people, and not being bored and the perceived barrier of not liking physical activity mediated several associations between peer and parental variables and girls' physical activity, with some of the mediated proportions exceeding 60%. Conclusions : This study contributed to a better understanding of the complexity of how parental and peer factors work together with personal factors to influence the physical activity levels of adolescent girls with a lower educational level. Interventions should involve both peers and parents, as they may influence girls' physical activity both directly and indirectly through the internalisation of several personal variables, such as self-efficacy to be active and the perceived benefit of having fun