Karsten Hollander

Effects of footwear on treadmill running biomechanics in preadolescent children

While recent research debates the topic of natural running in adolescents and adults, little is known about the influence of footwear on running patterns in children. The purpose of this study was to compare shod and barefoot running gait biomechanics in preadolescent children. Kinematic and ground reaction force data of 36 normally developed children aged 6-9 years were collected during running on an instrumented treadmill. Running conditions were randomized for each child in order to compare barefoot running with two different shod conditions: a cushioned and a minimalistic running shoe. Primary outcome was the ankle angle at foot strike. Secondary outcomes were knee angle, maximum and impact ground reaction forces, presence of rear-foot strike, step width, step length and cadence. Ankle angle at foot strike differed with statistical significance (p < 0.001) between conditions. Running barefoot reduced the ankle angle at foot strike by 5.97° [95% CI, 4.19; 7.75] for 8 kmh(-1) and 6.18° [95% CI, 4.38; 7.97] for 10 kmh(-1) compared to the cushioned shoe condition. Compared to the minimalistic shoe condition, running barefoot reduced the angle by 1.94° [95% CI, 0.19°; 3.69°] for 8 kmh(-1) and 1.38° [95% CI, -3.14°; 0.39°] for 10 kmh(-1). Additionally, using footwear significantly increased maximum and impact ground reaction forces, step length, step width and rate of rear-foot strike. In conclusion, preadolescent running biomechanics are influenced by footwear, especially by cushioned running shoes. Health professionals and parents should keep this in mind when considering footwear for children.

Comparison of minimalist footwear strategies for simulating barefoot running: a randomized crossover study.

Possible benefits of barefoot running have been widely discussed in recent years. Uncertainty exists about which footwear strategy adequately simulates barefoot running kinematics. The objective of this study was to investigate the effects of athletic footwear with different minimalist strategies on running kinematics. Thirty-five distance runners (22 males, 13 females, 27.9 ± 6.2 years, 179.2 ± 8.4 cm, 73.4 ± 12.1 kg, 24.9 ± 10.9 km.week-1) performed a treadmill protocol at three running velocities (2.22, 2.78 and 3.33 m.s-1) using four footwear conditions: barefoot, uncushioned minimalist shoes, cushioned minimalist shoes, and standard running shoes. 3D kinematic analysis was performed to determine ankle and knee angles at initial foot-ground contact, rate of rear-foot strikes, stride frequency and step length. Ankle angle at foot strike, step length and stride frequency were significantly influenced by footwear conditions (p<0.001) at all running velocities. Posthoc pairwise comparisons showed significant differences (p<0.001) between running barefoot and all shod situations as well as between the uncushioned minimalistic shoe and both cushioned shoe conditions. The rate of rear-foot strikes was lowest during barefoot running (58.6% at 3.33 m.s-1), followed by running with uncushioned minimalist shoes (62.9%), cushioned minimalist (88.6%) and standard shoes (94.3%). Aside from showing the influence of shod conditions on running kinematics, this study helps to elucidate differences between footwear marked as minimalist shoes and their ability to mimic barefoot running adequately. These findings have implications on the use of footwear applied in future research debating the topic of barefoot or minimalist shoe running.

Growing-up (habitually) barefoot influences the development of foot and arch morphology in children and adolescents

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.

Long-term Effects of Habitual Barefoot Running and Walking: A Systematic Review.

Introduction Barefoot locomotion is widely believed to be beneficial for motor development and biomechanics but are implied to be responsible for foot pathologies and running-related injuries. Although most of available studies focused on acute effects of barefoot running and walking little is known regarding the effects of long-term barefoot versus shod locomotion. The purpose of this study was to systematically review the literature to evaluate current evidence of habitual barefoot (HB) versus habitual shod locomotion on foot anthropometrics, biomechanics, motor performance, and pathologies. Methods Four electronic databases were searched using terms related to habitually barefoot locomotion. Relevant studies were identified based on title, abstract, and full text, and a forward (citation tracking) and backward (references) search was performed. Risk of bias was assessed, data pooling, and meta-analysis (random effects model) performed and finally levels of evidence determined. Results Fifteen studies with 8399 participants were included. Limited evidence was found for a reduced ankle dorsiflexion at footstrike (pooled effect size, −3.47; 95% confidence interval [CI], −5.18 to −1.76) and a lower pedobarographically measured hallux angle (−1.16; 95% CI, −1.64 to −0.68). HB populations had wider (0.55; 95% CI, 0.06–1.05) but no shorter (−0.22; 95% CI, −0.51 to 0.08) feet compared with habitual shod populations. No differences in relative injury rates were found, with limited evidence for a different body part distribution of musculoskeletal injuries and more foot pathologies and less foot deformities and defects in HB runners. Conclusions Only limited or very limited evidence is found for long-term effects of HB locomotion regarding biomechanics or health-related outcomes. Moreover, no evidence exists for motor performance. Future research should include prospective study designs.

Balance training improves memory and spatial cognition in healthy adults

Physical exercise has been shown to improve cognitive functions. However, it is still unknown which type of exercise affects cognition. In the present study, we tested the hypothesis that a demanding balance training program improves memory and spatial cognition. Forty healthy participants aged 19–65 years were randomly assigned to either a balance or relaxation training intervention. Each group exercised twice a week for a total of 12 weeks. Pre- and posttests assessed balance performance, cardiorespiratory fitness, memory, spatial cognition, and executive functions. Only the balance group significantly increased in balance performance from pre- to posttest, while cardiorespiratory fitness remained unchanged in both groups. Moreover, the balance group significantly improved in memory and spatial cognition. Effects on executive functions were not observed. These results suggest that balance training is capable of improving particularly memory and spatial cognition. Therefore, an increase in cardiorespiratory fitness does not seem to be necessary to induce beneficial effects of physical exercise on cognition. It might be speculated that stimulating the vestibular system during balance training induces changes of the hippocampus and parietal cortex possibly via direct pathways between the vestibular system and these brain regions.

Foot Strike Patterns Differ Between Children and Adolescents Growing up Barefoot vs. Shod

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 (OR barefoot-jogging =0.82, 95% CI, 0.71 to 0.96, p=0.014; OR barefoot-running =0.58, 95% CI, 0.50 to 0.67, p<0.001 and OR shod-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.

Reliability and Correlation of Static and Dynamic Foot Arch Measurement in a Healthy Pediatric Population

BACKGROUND Measurement of the medial longitudinal foot arch in children is a controversial topic, as there are many different methods without a definite standard procedure. The purpose of this study was to 1) investigate intraday and interrater reliability regarding dynamic arch index and static arch height, 2) explore the correlation between both arch indices, and 3) examine the variation of the medial longitudinal arch at two different times of the day. METHODS Eighty-six children (mean ± SD age, 8.9 ± 1.9 years) participated in the study. Dynamic footprint data were captured with a pedobarographic platform. For static arch measurements, a specially constructed caliper was used to assess heel-to-toe length and dorsum height. A mixed model was established to determine reliability and variation. RESULTS Reliability was found to be excellent for the static arch height index in sitting (intraday, 0.90; interrater, 0.80) and standing positions (0.88 and 0.85) and for the dynamic arch index (both 1.00). There was poor correlation between static and dynamic assessment of the medial longitudinal arch (standing dynamic arch index, r = -0.138; sitting dynamic arch index, r = -0.070). Static measurements were found to be significantly influenced by the time of day (P < .001), whereas the dynamic arch index was unchanged (P = .845). This study revealed some further important findings. The static arch height index is influenced by gender (P = .004), whereas dynamic arch index is influenced by side (P = .011) and body mass index (P < .001). CONCLUSIONS Dynamic and static foot measurements are reliable for medial longitudinal foot arch assessment in children. The variation of static arch measurements during the day has to be kept in mind. For clinical purposes, static and dynamic arch data should be interpreted separately.

Motor Skills of Children and Adolescents Are Influenced by Growing up Barefoot or Shod

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 20 m 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.

Prospective monitoring of health problems among recreational runners preparing for a half marathon

Objectives While the health benefits of running are legitimately advocated, participation in running can also lead to health problems. There is a high range of reported prevalence rates especially of running-related overuse injuries in high-level athletes and during competition. Little consensus exists for acute injuries and illnesses especially in recreational runners. Therefore, the aim of this study was to record the prevalence of health problems in recreational long-distance runners preparing for an event. Methods Recreational runners aged 18–65 years who were registered 13 weeks prior to a half-marathon running event were invited to take part in this study. Participants were prospectively monitored weekly over 13 weeks by applying a standardised surveillance system for injuries and illnesses (Oslo Sports Trauma Research Center questionnaire). From this, prevalence and severity of acute and overuse injuries, as well as illnesses, were calculated. Results We received 3213 fully answered questionnaires from 327 participants (40.7% female, 40.9±11.7 years of age, 31.5±21.1 km weekly mileage, 8.3±7.8 years of running experience). At any point in time over the preparation phase, 37.3% of the participants had health problems. Overuse injuries were the major burden (18%). They were followed by illnesses (14.1%) and acute injuries (7.9%). The median weekly severity score was 56.5 (IQR 37.0–58.0). Conclusion The high prevalence of health problems in our cohort suggests that future efforts are needed to further specify the underlying mechanism and develop adequate prevention strategies for recreational runners.

Improving Running Economy by Transitioning to Minimalist Footwear: A Randomised Controlled Trial

OBJECTIVES Ongoing debates about benefits and risks of barefoot- and minimally-shod running have, to date, revealed no conclusive findings for long-term effects on physical performance. The purpose of this study was to examine the effects of an 8-week transition to minimalist footwear (MFW) on running economy (RE). DESIGN Randomised controlled trial. METHODS Thirty-two male, habitually-shod runners were assigned randomly to an 8-week training intervention either in minimalist (=intervention group) or conventional running shoes (=control group). The intervention consisted of a gradual increase in use of the new footwear by 5% of the individual weekly distance. Before and after the intervention, a VO2max test was followed by a submaximal RE test at 70% and 80% of vVO2max in both shoe conditions 7days later. RE was measured at the submaximal tests and expressed as caloric unit cost (kcalkg-1km-1) and oxygen consumption (mlkg-1km-1). RESULTS RE improved in the intervention group over time compared to the control group with small to moderate effect sizes (ES) in both shoe conditions: Effects on RE (kcalkg-1km-1) in conventional running shoes: ES vVO270%: 0.68 (95% CI: -0.14 to 1.51), ES vVO280%: 0.78 (95% CI: 0-1.56). In minimalist footwear: ES vVO270%: 0.3 (95% CI: -0.54 to 1.14), ES vVO280%: 0.42 (95% CI: -0.41 to 1.25). These effects were not statistically significant (p>0.05). The repeated-measures ANOVA also showed no group by time interactions for all submaximal RE testing conditions (p>0.05). CONCLUSIONS Although not reaching statistical significance, training in MFW compared to CRS resulted in small to moderate improvements in RE.