Browsing by Author "Venter, Ranel"

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    The effects of being habitually barefoot on foot mechanics and motor performance in children and adolescents aged 6–18 years : study protocol for a multicenter crosssectional study (Barefoot LIFE project)
    (BioMed Central, 2016-09-02) Hollander, Karsten; Van der Zwaard, Babette C.; De Villiers, Johanna Elsabe; Braumann, Klaus-Michael; Venter, Ranel; Zech, Astrid
    Background: Barefoot locomotion has evoked an increasing scientific interest with a controversial debate about benefits and limitations of barefoot and simulated barefoot walking and running. While most current knowledge comes from cross sectional laboratory studies, the evolutionary perspective suggests the importance of investigating the long-term effects. Observing habitually barefoot populations could fill the current gap of missing high quality longitudinal studies. Therefore, the study described in this design paper aims to investigate the effects of being habitually barefoot on foot mechanics and motor performance of children and adolescents. Methods: This study has a cross-sectional, binational design and is part of the “Barefoot Locomotion for Individual Foot- and health Enhancement (Barefoot LIFE)” project. Two large cohorts (n(total) = 520) of healthy children and adolescents between 6 and 18 years of age will be included respectively in Germany and South Africa. A barefoot questionnaire will be used to determine habitually barefoot individuals. The testing will be school-based and include foot mechanical (static arch height index, dynamic arch index, foot pliability) and motor performance (coordination, speed, leg power) outcomes. Gender, BMI and level of physical activity will be considered for confounding. Discussion: The strength of this study is the comparison of two large cohorts with different footwear habits to determine long-term effects of being habitually barefoot on foot mechanics and motor performance
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    Foot strike patterns differ between children and adolescents growing up barefoot vs. shod
    (Georg Thieme Verlag, 2017) Hollander, Karsten; De Villiers, Johanna Elsabe; Venter, Ranel; Sehner, Susanne; Wegscheider, Karl; Braumann, Klaus-Michael; Zech, Astrid
    Effects of early and permanent footwear use are not well understood. The aim of this study was to investigate the effects of habituation to footwear on foot strike patterns of children and adolescents. Healthy habitually barefoot and shod participants (aged 6–18 years) from South Africa (n=288) and Germany (n=390) performed multiple 20-m jogging and running trials with and without shoes. Each foot strike was captured using a high-speed camera to determine a rearfoot or non-rearfoot strike. The probability of a rearfoot strike in both cohorts and each age was analyzed by using a mixed-effects logistic regression adjusted for possible confounders. Habitually barefoot children showed a higher probability of using rearfoot strikes than habitually shod children (p<0.001). The probability was age-dependent and decreased in habitually barefoot children with age (ORbarefoot-jogging=0.82, 95% CI, 0.71 to 0.96, p=0.014; ORbarefoot-running=0.58, 95% CI, 0.50 to 0.67, p<0.001 and ORshod-running=0.68, 95% CI, 0.59 to 0.79, p<0.001). In habitually shod children, the probability increased significantly for shod jogging (OR=1.19, 95% CI, 1.05 to 1.35, p=0.006). To conclude, foot strike patterns of children are influenced by habituation to footwear. Younger habitually barefoot children show higher rates of rearfoot strikes for shod and barefoot running, and it converges in later adolescence.
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    Growing-up (habitually) barefoot influences the development of foot and arch morphology in children and adolescents
    (Nature Research, 2017) Hollander, Karsten; De Villiers, Johanna Elsabe; Sehner, Susanne; Wegscheider, Karl; Braumann, Klaus-Michael; Venter, Ranel; Zech, Astrid
    The development of the human foot is crucial for motor learning in children and adolescents as it ensures the basic requirements for bipedal locomotion and stable standing. Although there is an ongoing debate of the advantages and disadvantages of early and permanent footwear use, the influence of regular barefootness on foot characteristics in different stages of child development has not been extensively evaluated. A multicenter epidemiological study was conducted to compare the foot morphology between habitually barefoot children and adolescents (N = 810) to age-, sex- and ethnicity-matched counterparts that are used to wearing shoes. While controlling for confounders, we found that habitual footwear use has significant effects on foot-related outcomes in all age groups, such as a reduction in foot arch and hallux angles. The results indicate an impact of habitual footwear use on the development of the feet of children and adolescents. Therefore, growing up barefoot or shod may play an important role for childhood foot development, implying long-term consequences for motor learning and health later in life.
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    Motor skills of children and adolescents are influenced by growing up barefoot or shod
    (Frontiers Media, 2018) Zech, Astrid; Venter, Ranel; De Villiers, Johanna E.; Sehner, Susanne; Wegscheider, Karl; Hollander, Karsten
    Background: The objective of this study was to evaluate the association between growing up barefoot or shod and the development of motor performance during childhood and adolescence. Methods: Habitual barefoot and shod children and adolescents between 6 and 18 years were recruited in South Africa and Germany. Participants completed balance, standing long jump and 20m sprint tests in barefoot and shod conditions. Outcomes were analyzed in separate mixed-effects linear regressions for three age groups according to stages of development (6–10, 11–14, and 15–18 years). All models were adjusted for confounders: sex, ethnicity, BMI, PAQ score and order of tests (barefoot vs. shod). Results: Three hundred and eight-five habitually barefoot and 425 habitually shod children participated. Significant age by footwear effects were found for the jump (p = 0.032) and sprint test (p = 0.041). Habitually barefoot children aged 6–10 years scored higher in the balance test (p = 0.015) and standing long jump (p = 0.005) whereas habitually shod children sprinted faster (p < 0.001). Faster sprint times were found for habitually shod participants between 11 and 14 years (p < 0.001). Habitually barefoot adolescents between 15 and 18 years of age showed a greater long jump distance (p < 0.001) but slower sprint times (p = 0.014) than shod adolescents. Conclusions: The results emphasize the importance of footwear habits for the development of motor skills during childhood and adolescence. Regular physical activities without footwear may be beneficial for the development of jumping and balance skills, especially in the age of 6 to 10 years.
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    Positional in-match running demands of university rugby players in South Africa
    (Frontiers Media, 2020) Donkin, Cameron; Venter, Ranel; Coetzee, Derik; Kraak, Wilbur Julio
    The implementation of the Varsity Cup rugby competition among South African universities has sparked interest in university rugby cultures around the country. The Varsity Cup has established itself as one of the most important rugby competitions for full-time students. The development of specific conditioning programs for rugby players requires a thorough understanding of the game and the unique demands of playing positions. Therefore, the study aimed to investigate the in-match running demands of South African university rugby players by using GPS during match play for primary and secondary positional groups. Rugby players (n = 40) from two universities were assessed during match play (n = 17) over a competitive season by using GPS. Players were grouped into two primary positional groups, forwards (n = 22) and backs (n = 18), and five secondary positional groups, tight forwards (n = 14), loose forwards (n = 8), half backs (n = 5), inside backs (n = 6), and outside backs (n = 7). The GPS analysis provided the following match-play movements: total distance, high-speed meters, maximum velocity, match intensity, the number of accelerations and decelerations, and velocity zone. Halfbacks recorded the highest total distance (6620.9 ± 784.4 m; p = 0.02) and match intensity (77.7 ± 11.6 m/min; p = 0.01). Outside backs recorded the highest maximum velocity (8.385 ± 1.242 m/s; p = 0.00). Loose forwards registered the highest number of accelerations (385.5 ± 122.1) and decelerations (378.7 ± 108.1). Backs and their specific subgroups play at and within high velocity thresholds, significantly higher (p = 0.01) than that of the forwards. Forwards tend to be involved in a higher amount of accelerations and decelerations during match play, suggesting that forward play is at close quarters to the opposition. During university rugby matches, the backs covered greater distances and speeds than the forwards, whereas the forwards achieved more accelerations and decelerations than backs. Results from the study can assist Varsity Cup strength and conditioning coaches to prepare players for the position-specific demands of the competition.