Asymmetries of foot strike patterns during running in high-level female and male soccer players.

BACKROUND: Foot strike pattern (FSP) is defined by the way the foot makes initial ground contact and is influenced by intrinsic and extrinsic factors. This study investigated the effect of running speed on asymmetries of FSP. METHODS: Seventeen female and nineteen male soccer players performed an incremental running test on an instrumented treadmill starting at 2.0 m/s until complete exhaustion. Force plate data were used to categorize foot strikes into rearfoot (RFS) and non-rearfoot strikes. Additionally, peak vertical ground reaction force (peakGRF) and stride time were calculated. The symmetry index (SI) was used to quantify lateral asymmetries between legs. RESULTS: The SI indicated asymmetries of the rate of RFS (%RFS) of approximately 30% at slow running speed which decreased to 4.4% during faster running speed (p = 0.001). There were minor asymmetries in peakGRF and stride time at each running stage. Running speed influenced %RFS (p < 0.001), peakGRF (p < 0.001) and stride time (p < 0.001). Significant interaction effects between running speed and sex were shown for %RFS (p = 0.033), peakGRF (p < 0.001) and stride time (p = 0.041). CONCLUSION: FSP of soccer players are asymmetric at slower running speed, but symmetry increases with increasing speed. Future studies should consider that FSP are non-stationary and influenced by running speed but also differ between legs.

Physical Activity During Lockdowns Associated with the COVID-19 Pandemic: A Systematic Review and Multilevel Meta-analysis of 173 Studies with 320,636 Participants.

BACKGROUND: Many countries have restricted public life in order to contain the spread of the novel coronavirus (SARS-CoV2). As a side effect of related measures, physical activity (PA) levels may have decreased. OBJECTIVE: We aimed (1) to quantify changes in PA and (2) to identify variables potentially predicting PA reductions. METHODS: A systematic review with random-effects multilevel meta-analysis was performed, pooling the standardized mean differences in PA measures before and during public life restrictions. RESULTS: A total of 173 trials with moderate methodological quality (modified Downs and Black checklist) were identified. Compared to pre-pandemic, total PA (SMD - 0.65, 95% CI - 1.10 to - 0.21) and walking (SMD - 0.52, 95% CI - 0.29 to - 0.76) decreased while sedentary behavior increased (SMD 0.91, 95% CI: 0.17 to 1.65). Reductions in PA affected all intensities (light: SMD - 0.35, 95% CI - 0.09 to - 0.61, p = .013; moderate: SMD - 0.33, 95% CI - 0.02 to - 0.6; vigorous: SMD - 0.33, - 0.08 to - 0.58, 95% CI - 0.08 to - 0.58) to a similar degree. Moderator analyses revealed no influence of variables such as sex, age, body mass index, or health status. However, the only continent without a PA reduction was Australia and cross-sectional trials yielded higher effect sizes (p < .05). CONCLUSION: Public life restrictions associated with the COVID-19 pandemic resulted in moderate reductions in PA levels and large increases in sedentary behavior. Health professionals and policy makers should therefore join forces to develop strategies counteracting the adverse effects of inactivity.

The Interval Between Matches Significantly Influences Injury Risk in Field Hockey.

Fixture congestion increases injury risk in football, but how it impacts other sports is unclear. The aim of this study was to identify associations between match density and injury incidence in field hockey players. Injury data from a prospective cohort study of professional and youth players was analysed in two ways. Inter-match intervals were clustered into<2424-hours, 3-7-days, and 13 + days, and injury rate ratios (IRR) were calculated to identify differences between clusters in match injuries. Separately, a Lasso-penalised Poisson regression model was used to determine the association between match load across the previous 24-hours, 3-days, 7-days and 14-days, and match and training injuries. Injury rates in matches within 24-hours of the previous match were mostly significantly higher when compared to matches after 3-7-days (IRRs: 3.78; 6.77, P = 0.003; 0.005). While a higher match exposure in the preceding 24-hour and 3-day periods was associated with higher combined match and training injury rates (ß̂ = 0.0001; 0.0018), a higher match exposure in the previous 7-and 14-day periods was associated with a reduced injury rate (ß̂ = -0.0001; -0.0005). Due to the increased injury risk in matches 3-days and especially 24-hours following the previous fixture, match distribution should be cautiously planned.

Sex differences in injury rates in team-sport athletes: A systematic review and meta-regression analysis.

BACKGROUND: Team-sport players have a particularly high injury risk. Although female sex is considered a risk factor, it is still unknown whether female and male team-sport players, in fact, differ in their injury rates. We aimed to compare injury rates between female and male players by systematically reviewing and meta-analyzing injury surveillance studies of both sexes in order to evaluate sex-specific differences in team-sport injuries. METHODS: Studies that prospectively collected injury data for high-level female and male players (age ≥16 years) in basketball, field hockey, football (soccer), handball, rugby (union and sevens), and volleyball were included. Two reviewers (AZ and ALR) independently assessed study quality and extracted data for overall, match, training, and severe injuries (>28 days' time loss) as well as data regarding injury locations and types. Incidence rate ratios (IRRs) were pooled in a meta-analysis, and meta-regression analysis was performed when 10 or more studies were available. RESULTS: Of 20 studies, 9 studies reported injury data from football, 3 studies from rugby, 3 studies from handball, 1 study from basketball, 1 study from field hockey, 2 studies from volleyball, and 1 study from basketball and field hockey. For overall injuries, the pooled IRR = 0.86 (95% confidence interval (95%CI): 0.76-0.98) indicated significantly more injuries in male than in female players. For injury location, the pooled IRR showed higher injury rates in male athletes than in female athletes for upper extremity, hip/groin, thigh, and foot injuries. Female players had a significantly higher rate of anterior cruciate ligament injuries (IRR = 2.15, 95%CI: 1.27-3.62) than male players. No significant sex-specific differences in IRR were found for match, training, severe injuries, concussions, or ankle sprains. CONCLUSION: Our meta-analysis provides evidence for sex-specific differences in the injury rates in team sports. Further epidemiological studies including both sexes in sports other than football are needed in order to strengthen the evidence.

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.

Sex-Specific Differences in Running Injuries: A Systematic Review with Meta-Analysis and Meta-Regression.

BACKGROUND: Running is a popular sport with high injury rates. Although risk factors have intensively been investigated, synthesized knowledge about the differences in injury rates of female and male runners is scarce. OBJECTIVE: To systematically investigate the differences in injury rates and characteristics between female and male runners. METHODS: Database searches (PubMed, Web of Science, PEDro, SPORTDiscus) were conducted according to PRISMA guidelines using the keywords "running AND injur*". Prospective studies reporting running related injury rates for both sexes were included. A random-effects meta-analysis was used to pool the risk ratios (RR) for the occurrence of injuries in female vs. male runners. Potential moderators (effect modifiers) were analysed using meta-regression. RESULTS: After removal of duplicates, 12,215 articles were screened. Thirty-eight studies were included and the OR of 31 could be pooled in the quantitative analysis. The overall injury rate was 20.8 (95% CI 19.9-21.7) injuries per 100 female runners and 20.4 (95% CI 19.7-21.1) injuries per 100 male runners. Meta-analysis revealed no differences between sexes for overall injuries reported per 100 runners (RR 0.99, 95% CI 0.90-1.10, n = 24) and per hours or athlete exposure (RR 0.94, 95% CI 0.69-1.27, n = 6). Female sex was associated with a more frequent occurrence of bone stress injury (RR (for males) 0.52, 95% CI 0.36-0.76, n = 5) while male runners had higher risk for Achilles tendinopathies (RR 1. 86, 95% CI 1.25-2.79, n = 2). Meta-regression showed an association between a higher injury risk and competition distances of 10 km and shorter in female runners (RR 1.08, 95% CI 1.00-1.69). CONCLUSION: Differences between female and male runners in specific injury diagnoses should be considered in the development of individualised and sex-specific prevention and rehabilitation strategies to manage running-related injuries.

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.

Comparison of 10 vs. 20 min neuromuscular training for the prevention of lower extremity injuries in male youth football: A cluster randomised controlled trial.

The aim of this study was to compare the effects of 20 min neuromuscular training with a programme of 10 min in youth football players. 342 (15.4 ± 1.7 years) male football players from 18 teams were included, and cluster-randomized by team into two intervention groups. Both groups performed an injury prevention programme twice a week over five months using the same exercises but a different duration. The first intervention group (INT10, n = 175) performed the programme for 10 min, the second intervention group (INT20, n = 167) for 20 min. Primary outcomes were lower extremity (LE) injuries. Secondary outcomes were injury type, severity, mechanism and compliance to the intervention. 13 teams with 185 players were included for final analysis. No significant group difference was found between INT10 (6.37 per 1000 h) and INT20 (7.20 per 1000 h) for the incidence rate ratio of the lower extremities (IRR = 1.03, 95% confidence interval 0.59, 1.79), nor for the distribution of injury location, type, severity or mechanism. The results show that performing preventive exercises for 10 min is no less effective than 20 min in youth football players. Shorter training sessions can, therefore, be effectively used for injury prevention. TRIAL REGISTRATION: DRKS00015282.

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 relationship between static and dynamic foot posture and running biomechanics: A systematic review and meta-analysis.

BACKGROUND: Medial longitudinal arch characteristics are thought to be a contributing factor to lower limb running injuries. Running biomechanics associated with different foot types have been proposed as one of the potential underlying mechanisms. However, no systematic review has investigated this relationship. RESEARCH QUESTION: The aim of this study was to conduct a systematic literature search and synthesize the evidence about the relationship between foot posture and running biomechanics. METHODS: For this systematic review and meta-analysis different electronic databases (Pubmed, Web of Science, Cochrane, SportDiscus) were searched to identify studies investigating the relationship between medial longitudinal arch characteristics and running biomechanics. After identification of relevant articles, two independent researchers determined the risk of bias of included studies. For homogenous outcomes, data pooling and meta-analysis (random effects model) was performed, and levels of evidence determined. RESULTS: Of the 4088 studies initially identified, a total of 25 studies were included in the qualitative review and seven in the quantitative analysis. Most studies had moderate and three studies a low risk of bias. Moderate evidence was found for a relationship between foot posture and subtalar joint kinematics (small pooled effects: -0.59; 95%CI -1.14 to - 0.003) and leg stiffness (small pooled effect: 0.59; 95%CI 0.18 to 0.99). Limited or very limited evidence was found for a relationship with forefoot kinematics, tibial/leg rotation, tibial acceleration/shock, plantar pressure distribution, plantar fascia tension and ankle kinetics as well as an interaction of foot type and footwear regarding tibial rotation. SIGNIFICANCE: While there is evidence for an association between foot posture and subtalar joint kinematics and leg stiffness, no clear relationship was found for other biomechanical outcomes. Since a comprehensive meta-analysis was limited by the heterogeneity of included studies future research would benefit from consensus in foot assessment and more homogenous study designs.

Kinesio Taping Improves Perceptions of Pain and Function of Patients With Knee Osteoarthritis: A Randomized, Controlled Trial.

Context: Although increasingly used for therapeutic treatment, only limited evidence exists regarding the effects of kinesio taping on patients with knee osteoarthritis (OA). Objective: To determine the effects of kinesio taping on pain, function, gait, and neuromuscular control concerning patients with knee OA. Design: Randomized sham-controlled trial. Setting: University laboratory. Participants: A total of 141 patients (65.1 [7.0] y) with a clinical and radiographic diagnosis of knee OA. Intervention: Kinesio tape, sham tape, or no tape for 3 consecutive days. Main Outcome Measures: Self-reported pain, stiffness, and function were measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Further tests included the Balance Error Scoring System, 10-m walk test, the maximum voluntary isometric contraction force of the quadriceps femoris, and knee active range of motion. Results: At baseline, there were no differences in all outcomes between groups except for knee flexion. Significant effects were found for WOMAC pain (tape vs sham, P = .05; tape vs control, P = .047), stiffness (tape vs sham, P = .01; tape vs control, P ≤ .001), and physical function (tape vs sham, P = .03; tape vs control P = .004). No interactions were found for balance, muscle strength, walking speed, or active range of motion. Conclusion: Wearing kinesio tape for 3 consecutive days had beneficial effects regarding self-reported clinical outcomes of pain, joint stiffness, and function. This emphasizes that kinesio taping might be an adequate conservative treatment for the symptoms of knee OA.

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.

Validity and Reliability of an Inertial Sensor-Based Knee Proprioception Test in Younger vs. Older Adults.

Diminishing proprioception caused by aging effects is associated with a higher risk to fall. However, existing measurement systems of proprioception are often expensive, time-consuming, or insufficient regarding reliability evaluation. Inertial sensor-based systems could address these issues. Consequently, this study sought to develop and evaluate an inertial sensor-based joint position sense test. Thereto, intra-session and inter-day test-retest reliability were investigated in a cross-over design. Twenty healthy younger (age: 22 ± 3 years) and 20 healthy older adults (age: 65 ± 5 years) participated in the study. We calculated the mean of the absolute error, the signed error, and the standard deviation of the signed error. Test-retest reliability was quantified by using the intraclass correlation coefficient as well as the bias and limits of agreement. To evaluate the possibility of capturing aging effects, and correspondingly a validation of the system, we calculated Cohen's d. For the intra-session reliability, fair to good agreements were achieved for the absolute and relative error in all target ranges. Compared to younger adults, we registered a declined joint position sense in older adults with high effects observed for the absolute error in a target range of 15-25 and 35-45° as well as for the variable error in the target ranges of 35-45 and 55-65°. We suggest that inertial sensor-based joint position sense tests are reliable and capable to measure aging effects on proprioception, and are therefore a low-cost and mobile alternative to existing methods.

Agreements and disagreements in exercise therapy prescriptions after hip replacement among rehabilitation professionals: a multicenter survey.

BACKGROUND: Exercise therapy following total hip replacement (THR) is considered to be important during the initial postoperative care, but till date only a few evidence-based recommendations exist. The aim of this survey was to identify prescription standards among different rehabilitation professionals, for the exercise therapy management after THR in Germany. METHODS: The study was a cross-sectional survey. Standardized questionnaires were sent to 38 eligible rehabilitation facilities in Germany. Participating surgeons, orthopaedic physicians, physiotherapists and exercise therapists rated the optimal early weight-bearing, resistance training, key components and dose of exercise therapy, and the hip loading during exercising. The returned questionnaires were then analyzed for level of agreement (≥80%) among respondents. RESULTS: 313 rehabilitation professionals from 28 clinics returned completed questionnaires and were considered eligible for analysis. Out of total respondents, 53.9% (cemented THR) and 18.2% (uncemented THR) recommended full weight-bearing within five days after surgery. Commencement of resistance training later than three weeks after surgery is recommended by 20.6% (36%) for cemented (uncemented) prosthesis. Feedback varied significantly amongst the professions. Regarding the overall objectives of rehabilitation after hip replacement, respondents agree in six out of eight requested items. Agreement concerning priorities of specific exercises was achieved in three out of twelve items. The recommended exercise therapy dose varied significantly with working experience (p = 0.02). CONCLUSION: Rehabilitation professionals mainly disagreed with the exercise therapy prescriptions following the total hip replacement during the initial postoperative care in Germany.

Minimalist, standard and no footwear on static and dynamic postural stability following jump landing.

In recreational sports, uncushioned, light-weight and minimalist shoes are increasingly used to imitate barefoot situations. Uncertainty exists whether these shoes provide sufficient stability during challenging movements. In this randomised crossover study, 35 healthy distance runners performed jump landing stabilisation and single-leg stance tests on a force plate, using four conditions in random order: barefoot, uncushioned minimalist shoes, cushioned ultraflexible shoes and standard running shoes. Ground reaction force (GRF) and centre of pressure (COP) data were used to determine unilateral jump landing stabilisation time and COP sway velocity during single-leg stance. Repeated measures analysis of variance revealed significant footwear interactions for medial-lateral (p < 0.001) and anterior-posterior COP sway velocity during standing (p < 0.001). The barefoot condition produced significantly greater postural sway velocities (p < 0.001) compared to all footwear conditions. No significant effects were found for jump landing stabilisation time. In conclusion, the results of this study indicate that increased shoe flexibility and reduced sole support have no, or only minor influence on static and dynamic postural control, and therefore, may not increase the risk of traumatic events during sports activities. However, barefoot conditions should be considered carefully when adequate postural control is needed.