Effects of elastic ankle support on running ankle kinematics in individuals with chronic ankle instability and healthy controls.

BACKGROUND: Individuals with chronic ankle instability (CAI) have an increased risk for recurrent injuries. The preventive effects of external ankle supports are not fully understood. This study aimed to examine the effect of elastic ankle support on running ankle kinematics. METHODS: 3D running gait analysis of individuals with and without CAI was conducted at three-minute-running trials at 2.78 m/s with and without elastic ankle support in a randomised order. Ankle kinematics and intra-individual standard deviations (variability) were calculated at each percent of the running gait cycle. Group and ankle support effects were calculated using statistical parameter mapping. RESULTS: Twenty-seven individuals were analysed (CAI: n = 14, controls: n = 13). When wearing ankle support, CAI individuals showed significantly decreased plantarflexion angles at 43-47 % (p = 0.033) and 49-51 % (p = 0.043) of the running gait cycle compared to normal running. In healthy controls, no differences in ankle angles between both conditions were found. Comparisons between CAI individuals and healthy controls showed statistically significant differences in the plantar-/dorsiflexion angles at 38-41 % (p = 0.044) with ankle support and at 34-46 % (p = 0.004) without ankle support. Significant ankle angle variability differences were found for ankle in-/eversion between CAI individuals and healthy controls (p = 0.041) at 32-33 % of the running gait cycle. CONCLUSIONS: Elastic ankle support reduces the range of sagittal plane running ankle kinematics of CAI individuals but not of healthy controls. Further research is needed to evaluate the association between ankle support effects and the risk for recurrent ankle sprains.

Effects of a 10 vs. 20-Min Injury Prevention Program on Neuromuscular and Functional Performance in Adolescent Football Players.

BACKGROUND: Regular injury prevention training is not only effective in reducing sports injury rates, but also in improving neuromuscular and performance-related variables. However, it is currently unknown if this effect can be modified by varying the training dosage. OBJECTIVE: To compare the effects of two injury prevention programmes with a different training duration on neuromuscular control and functional performance in adolescent football players. METHODS: 342 (15.4 ± 1.7 years) male football players from 18 teams were initially included. The teams were cluster-randomized into two intervention groups. Both groups performed an injury prevention program twice a week during one football season (10 months) using the same exercises but a different duration. One intervention group (INT10, n = 175) performed the program for 10 min, while the other intervention group (INT20, n = 167) for 20 min. At the beginning and end of the season, balance control (Balance Error Scoring System = BESS), jump performance (Squat Jump, Countermovement Jump) and flexibility (Sit and Reach Test, ankle flexibility, hip flexibility) tests were performed. For the final analysis, nine teams with 104 players were considered. RESULTS: Significant group by time interactions were found for the sit and reach test (p < 0.001) and ankle flexibility (p < 0.001) with higher improvements in the INT20 group. Improvements over the period of one season but no group differences were found for the BESS, Squat Jump and hip flexibility. CONCLUSION: Within a single training session, performing structured neuromuscular training with a longer duration is more effective than a shorter duration for improving lower extremity flexibility.

Is an Elastic Ankle Support Effective in Improving Jump Landing Performance, and Static and Dynamic Balance in Young Adults With and Without Chronic Ankle Instability?

CONTEXT: In some patients, ankle sprains lead to chronic symptoms like pain or muscular weakness called chronic ankle instability (CAI). External ankle supports have shown to be effective in preventing sprains and reducing recurrence, but the underlying mechanisms are unclear. As sensorimotor variables are associated with injury incidence, an influence of external ankle support on landing performance and balance seems plausible. OBJECTIVE: To analyze the effects of an elastic ankle support on jump landing performance and static and dynamic balance in patients with CAI and healthy controls. DESIGN: Crossover study. SETTING: Functional tests in a laboratory setting. PATIENTS OR OTHER PARTICIPANTS: Twenty healthy students and 20 patients with CAI were included for study participation based on their scores in ankle stability and function questionnaires. INTERVENTION: Healthy and CAI participants performed each test with and without an elastic ankle support. MAIN OUTCOME MEASURES: (1) Jump landing performance was measured with the Landing Error Scoring System, (2) static balance was assessed with the Balance Error Scoring System, and (3) dynamic balance was assessed using the Y Balance Test. Linear mixed models were used to analyze the effects of the elastic ankle support on sensorimotor parameters. RESULTS: Healthy controls performed significantly better in the Landing Error Scoring System (P = .01) and Y Balance Test anterior direction (P = .01). No significant effects of elastic ankle support on Landing Error Scoring System, Balance Error Scoring System, or Y Balance Test performance were observed in the CAI or control group. There were no significant group-by-ankle support interactions. CONCLUSIONS: In the current study, the acute use of elastic ankle support was ineffective for enhancing jump landing performance, and static and dynamic balance. Further research is needed to identify the underlying mechanisms of the preventive effects of elastic ankle support.

The influence of biological maturity on motor performance among habitually barefoot versus habitually shod adolescents.

Biological maturation is associated with physiological changes which in turn affect motor performance. No study has assessed the association between growing up habitually shod versus habitually barefoot and motor performance in the context of maturation, so this approach is unique. The purpose of this study was to examine the influence of biological maturity on motor performance dependent on the participants' footwear habits. Sixty-five German habitually shod (mean age 13.28 ± 0.83 years) and fifty-five South African habitually barefoot (mean age 13.38 ± 0.87 years) participants were included. Dynamic postural control was determined via backward balancing, explosive strength by standing long jump and sprinting performance based on a 20-m sprinting test. All tests were performed barefoot and shod. Biological maturation was calculated by using the maturity offset value. Linear mixed models were used to analyse interactions between the maturity offset value, footwear habits and motor performance. Throughout maturation, there was a significant difference between habitually barefoot and habitually shod balance performance (P = 0.001). Maturation led to balance improvements in habitually barefoot adolescents, but not in habitually shod adolescents. No such differences could be observed for standing long jump and 20-m sprint performance. Maturity offset was a significant predictor for jumping and sprinting performances (P < 0.001), independent of being habitually barefoot or habitually shod. Better performances could be observed in more mature subjects. Biological maturation seems to be a relevant predictor for motor performance characteristics for the jumping and sprinting performance in adolescents.

Influence of biological maturity on static and dynamic postural control among male youth soccer players.

BACKGROUND: Peak height velocity has been reported to be associated with the phenomenon of adolescent awkwardness, a temporary disruption in motor skills, and an increase in injuries in some adolescents. To date, it is not entirely clear which motor abilities are deficient during the phase of rapid growth. RESEARCH QUESTION: We hypothesized that static as well as dynamic postural control is influenced by biological maturation. METHODS: The study was conducted in a prospective, cross-sectional design. Maturity offset, a somatic indicator for biological maturation was captured for n = 99 male soccer players (13.7 ± 0.5 years). Static and dynamic balance were assessed by the Balance Error Scoring System (BESS) and the Y-Balance Test (YBT), respectively. Influences of biological maturation on balance performances have been analyzed by linear mixed models. RESULTS: Linear mixed model analyses revealed that biological maturation is significantly associated with the total BESS score (p = 0.022, b = 2.195) as well as the YBT anterior (right leg: p = 0.023, b = -0.022; left leg: p = 0.015, b = -0.024) and posteromedial reach directions (left leg: p = 0.02, b = -0.029). No significant associations were found for the other YBT distances. SIGNIFICANCE: Based on our results, maturation seems to have a considerable influence on postural control. It might be that deficits in balance performance contribute to the phenomenon of adolescent awkwardness and therefore lead to an increased injury risk during the adolescent growth spurt. To possibly prevent injuries in youth soccer, biological maturation should be taken into consideration in youth sport coaching.