How do sports injury epidemiological outcomes vary depending on athletes' response rates to a weekly online questionnaire? An analysis of 39-week follow-up from 391 athletics (track and field) athletes.

OBJECTIVE: To explore how sports injury epidemiological outcomes (i.e., prevalence, average prevalence, incidence, burden, and time to first injury) vary depending on the response rates to a weekly online self-reported questionnaire for athletes. METHODS: Weekly information on athletics injuries and exposure from 391 athletics (track and field) athletes was prospectively collected over 39 weeks (control group of the PREVATHLE randomized controlled trial) using an online self-reported questionnaire. The data were used to calculate sports injury epidemiological outcomes (i.e., prevalence, average prevalence, incidence, burden, and time to first injury) for sub-groups with different minimum individual athletes' response rates (i.e., from at least 100%, at least 97%, at least 95%, … to at least 0% response rate). We then calculated the relative variation between each sub-group and the sub-group with a 100% response rate as a reference. A substantial variation was considered when the relative variation was greater than one SD or 95% CI of the respective epidemiological outcome calculated in the sub-group with a 100% response rate. RESULTS: Of 15 249 expected weekly questionnaires, 7209 were completed and returned, resulting in an overall response rate of 47.3%. The individual athletes' response rates ranged from 0% (n = 51) to 100% (n = 100). The prevalence, average weekly prevalence, and time to first injury only varied substantially for the sub-groups below a 5%, 10% and 18% minimum individual response rate, respectively. The incidence and injury burden showed substantial variations for all sub-groups with a response rate below 100%. CONCLUSIONS: Epidemiological outcomes varied depending on the minimum individual athletes' response rate, with injury prevalence, average weekly prevalence, and time to first injury varying less than injury incidence and injury burden. This highlights the need to take into account the individual response rate when calculating epidemiological outcomes, and determining the optimal study-specific cut-offs of the minimum individual response rate needed.

The effect of repeated concussions on clinical and neurocognitive symptom severity in different contact sports.

INTRODUCTION: The potential consequences of repeated concussions in sport are well documented. However, it remains unclear whether the cumulative impact of sports-related concussions differs between different contact sports. Therefore, the aim of the current study was to investigate the cumulative effects of sports-related concussions on clinical and neurocognitive health in different contact sports. MATERIALS AND METHODS: In a prospective multicenter study, we examined 507 (74 females) active professional athletes between 18 and 40 years of age from five different contact sports (soccer, handball, American football, basketball, and ice hockey). Data collection involved concussion history, clinical symptom evaluation, neurocognitive assessment, and the collection of other sports-related information. Composite scores were built for clinical symptoms (such as neck pain and balance disturbances) and for neurocognitive symptoms (such as memory and attention impairments). RESULTS: Athletes having suffered 3+ concussions in the past showed disproportionally higher clinical symptom severity than athletes with less than three concussions across all sports. The level of clinical symptom burden in athletes with 3+ concussions indicated mild impairment. The number of past concussions did not affect neurocognitive performance. DISCUSSION: Repeated sports-related concussions appear to have a cumulative impact on clinical-but not cognitive-symptom severity. Although clinical symptom burden in athletes with 3+ concussions in the past was not alarmingly high yet in our sample, increased caution should be advised at this point. Despite few exceptions, results are similar for different contact sports, suggesting a similar multidisciplinary concussion management across all types of sport.

Use of extracorporeal shockwave therapies for athletes and physically active individuals: a systematic review.

OBJECTIVE: To determine the efficacy of extracorporeal shockwave therapy (ESWT) and investigate outcomes following the use of ESWT for athletes and physically active individuals. DESIGN: Systematic review. DATA SOURCES: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and searched four databases: PubMed (NLM), Embase (Elsevier), CINAHL Complete (EBSCO) and Web of Science (Clarivate). ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Included studies were randomised controlled trials, cohort and case-control studies, cases series and reports that evaluated outcomes following ESWT for athletes, physically active individuals and occupational groups requiring regular physical activity such as military cadets. RESULTS: 56 studies with 1874 athletes or physically active individuals were included. Using the Oxford level of evidence rating, included studies were 18 level I (32.1%), 3 level II (5.4%), 10 level III (17.9%), 13 level IV (23.2%) and 12 level V (21.4%). Based on the level I studies, ESWT may be effective alone in plantar fasciitis, lateral epicondylitis and proximal hamstring tendinopathy and as an adjunct to exercise treatment in medial tibial stress syndrome and osteitis pubis in athletes or physically active individuals. In most studies, athletes were allowed to continue activities and training and tolerated ESWT with minimal side effects. CONCLUSION: ESWT may offer an efficacious treatment alone or as an adjunct to concurrent exercise therapy in selected sports-related injuries and without major adverse events. Further high-level research is needed to better define the role and clinical outcomes of ESWT.

Return to sport following low-risk and high-risk bone stress injuries: a systematic review and meta-analysis.

OBJECTIVE: Bone stress injuries (BSIs) are classified in clinical practice as being at low- or high-risk for complication based on the injury location. However, this dichotomous approach has not been sufficiently validated. The purpose of this systematic review was to examine the prognostic role of injury location on return-to-sport (RTS) and treatment complications after BSI of the lower extremity and pelvis. DESIGN: Systematic review and meta-analysis. DATA SOURCES: PubMed, Web of Science, Cochrane CENTRAL and Google Scholar databases were searched from database inception to December 2021. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Peer-reviewed studies that reported site-specific RTS of BSIs in athletes. RESULTS: Seventy-six studies reporting on 2974 BSIs were included. Sixteen studies compared multiple injury sites, and most of these studies (n=11) described the anatomical site of injury as being prognostic for RTS or the rate of treatment complication. Pooled data revealed the longest time to RTS for BSIs of the tarsal navicular (127 days; 95% CI 102 to 151 days) and femoral neck (107 days; 95% CI 79 to 135 days) and shortest duration of time for BSIs of the posteromedial tibial shaft (44 days, 95% CI 27 to 61 days) and fibula (56 days; 95% CI 13 to 100 days). Overall, more than 90% of athletes successfully returned to sport. Treatment complication rate was highest in BSIs of the femoral neck, tarsal navicular, anterior tibial shaft and fifth metatarsal; and lowest in the fibula, pubic bone and posteromedial tibial shaft. CONCLUSION: This systematic review supports that the anatomical site of BSIs influences RTS timelines and the risk of complication. BSIs of the femoral neck, anterior tibial shaft and tarsal navicular are associated with increased rates of complications and more challenging RTS. PROSPERO REGISTRATION NUMBER: CRD42021232351.

Injuries and Illnesses During the 53rd FIS Nordic World Ski Championships 2021 in Oberstdorf: A Prospective Cohort Study.

OBJECTIVE: For the 3 Nordic ski disciplines of cross-country skiing, Nordic combined, and ski jumping, data on injuries and illnesses during major sporting events only exist from the Winter Olympics of 2010 to 2018. So far, an investigation has not been conducted during the Nordic World Ski Championships. DESIGN: Prospective cohort study. SETTING: Fédération Internationale de Ski (FIS) Nordic World Ski Championships 2021 in Oberstdorf, Germany. PARTICIPANTS: Overall, 663 athletes from 65 nations participated in the FIS Nordic World Ski Championships 2021. The study population included 344 athletes from 32 nations. INTERVENTIONS: National medical teams were invited to report daily all newly incurred or exacerbated injuries and illnesses. MAIN OUTCOME MEASURES: All reported injuries and illnesses that occurred during the championships from February 23 until March 7, 2021, were analyzed. Injury and illness rates were calculated with 95% confidence intervals (95% CIs). RESULTS: The 32 reporting nations returned 88.4% of the daily report forms. The incidence of injuries was 4.7 (95% CI, 2.4-6.9) per 100 athletes in the 3 Nordic ski disciplines. The incidence of illness was also 4.7 (95% CI, 2.4-6.9) per 100 athletes with a relative proportion of infection-related illnesses of 31.3%. CONCLUSIONS: Although the incidence of injuries of the Nordic disciplines was comparable with those of the 2010 to 2018 Winter Olympics, the incidence of illnesses was lower than during the previous 3 Winter Olympic Games with a lower rate of infection-related illnesses. This might be caused by the high hygiene measures due to the coronavirus disease 2019 pandemic.

Adolescents running in conventional running shoes have lower vertical instantaneous loading rates but greater asymmetry than running barefoot or in partial-minimal shoes.

Footwear may moderate the transiently heightened asymmetry in lower limb loading associated with peak growth in adolescence during running. This repeated-measures study compared the magnitude and symmetry of peak vertical ground reaction force and instantaneous loading rates (VILRs) in adolescents during barefoot and shod running. Ten adolescents (age, 10.6 ± 1.7 years) ran at self-selected speed (1.7 ± 0.3 m/s) on an instrumented treadmill under three counter-balanced conditions; barefoot and shod with partial-minimal and conventional running shoes. All participants were within one year of their estimated peak height velocity based on sex-specific regression equations. Foot-strike patterns, peak vertical ground reaction force and VILRs were recorded during 20 seconds of steady-state running. Symmetry of ground reaction forces was assessed using the symmetry index. Repeated-measures ANOVAs were used to compare conditions (α=.05). Adolescents used a rearfoot foot-strike pattern during barefoot and shod running. Use of conventional shoes resulted in a lower VILR (P < .05, dz = 0.9), but higher VILR asymmetry (P < .05) than running barefoot (dz = 1.5) or in partial-minimal shoes (dz = 1.6). Conventional running shoes result in a lower VILR than running unshod or in partial-minimal shoes but may have the unintended consequence of increasing VILR asymmetry. The findings may have implications for performance, musculoskeletal development and injury in adolescents.

Video analysis of Achilles tendon ruptures in professional male football (soccer) reveals underlying injury patterns and provides strategies for injury prevention.

PURPOSE: In professional football (soccer), Achilles tendon ruptures are severe injuries. Video analysis promotes a better understanding of the underlying situational and biomechanical patterns, and provides a roadmap for future research to improve the management and prevention of Achilles tendon ruptures. The purpose of this study was to identify injury patterns contributing to acute Achilles tendon ruptures in professional male football players. METHODS: Professional male football players with an acute Achilles tendon rupture were identified using an online database. For every in-competition injury, the corresponding football match was detected. Video footage of the injury was accessed using Wyscout.com or publicly available video databases. Situational patterns and injury biomechanics of the injury frame were independently analysed by two reviewers using a standardised checklist and a motion analysis software. Finally, consensus was reached to describe the main injury patterns of Achilles tendon ruptures in professional male football players. RESULTS: The search identified video footage of 80 Achilles tendon ruptures in 78 players. Most injuries (94%) occurred through indirect or non-contact mechanisms. The kinematic analysis revealed characteristic joint positions at the time of injury consisting of hip extension, knee extension, ankle dorsiflexion, foot abduction, and foot pronation in most cases. The underlying direction of movement was from flexion to extension (knee) and from plantarflexion to dorsiflexion (ankle). Player actions identified as main injury patterns were stepping back (26%), landing (20%), running/sprinting (18%), jumping (13%), and starting (10%). CONCLUSION: Most Achilles tendon ruptures in professional male football players are closed-chain indirect or non-contact injuries. Sudden loading to the plantarflexor musculotendinous unit remains to be the main component for most cases. By achieving a better understanding of underlying injury mechanisms, this study provides new strategies for the prevention of Achilles tendon ruptures. LEVEL OF EVIDENCE: Level IV.

Hamstring injury patterns in professional male football (soccer): a systematic video analysis of 52 cases.

OBJECTIVE: To closely describe the injury inciting events of acute hamstring injuries in professional male football (soccer) using systematic video analysis. METHODS: Video footage from four seasons (2014-2019) of the two highest divisions in German male football was searched for moderate and severe (ie, time loss of >7 days) acute non-contact and indirect contact match hamstring injuries. Two raters independently categorised inciting events using a standardised procedure to determine specific injury patterns and kinematics. RESULTS: 52 cases of hamstring injuries were included for specific pattern analysis. The pattern analysis revealed 25 sprint-related (48%) and 27 stretch-related hamstring injuries (52%). All sprint-related hamstring injuries occured during linear acceleration or high-speed running. Stretch-related hamstring injuries were connected with closed chain movements like braking or stopping with a lunging or landing action and open chain movements like kicking. The kinematic analysis of stretch-related injuries revealed a change of movement involving knee flexion to knee extension and a knee angle of <45° at the assumed injury frame in all open and closed chain movements. Biceps femoris was the most affected muscle (79%) of all included cases. CONCLUSION: Despite the variety of inciting events, rapid movements with high eccentric demands of the posterior thigh are likely the main hamstring injury mechanism. This study provides important data about how hamstring injuries occur in professional male football and supports the need for demand-specific multicomponent risk reduction programmes.

Reliability of Running Stability during Treadmill and Overground Running.

Running stability is the ability to withstand naturally occurring minor perturbations during running. It is susceptible to external and internal running conditions such as footwear or fatigue. However, both its reliable measurability and the extent to which laboratory measurements reflect outdoor running remain unclear. This study aimed to evaluate the intra- and inter-day reliability of the running stability as well as the comparability of different laboratory and outdoor conditions. Competitive runners completed runs on a motorized treadmill in a research laboratory and overground both indoors and outdoors. Running stability was determined as the maximum short-term divergence exponent from the raw gyroscope signals of wearable sensors mounted to four different body locations (sternum, sacrum, tibia, and foot). Sacrum sensor measurements demonstrated the highest reliabilities (good to excellent; ICC = 0.85 to 0.91), while those of the tibia measurements showed the lowest (moderate to good; ICC = 0.55 to 0.89). Treadmill measurements depicted systematically lower values than both overground conditions for all sensor locations (relative bias = -9.8% to -2.9%). The two overground conditions, however, showed high agreement (relative bias = -0.3% to 0.5%; relative limits of agreement = 9.2% to 15.4%). Our results imply moderate to excellent reliability for both overground and treadmill running, which is the foundation of further research on running stability.

Stepping Back to Minimal Footwear: Applications Across the Lifespan.

Minimal footwear has existed for tens of thousands of years and was originally designed to protect the sole of the foot. Over the past 50 yr, most footwear has become increasingly more cushioned and supportive. Here, we review evidence that minimal shoes are a better match to our feet, which may result in a lower risk of musculoskeletal injury.

Apparent temperature and heat-related illnesses during international athletic championships: A prospective cohort study.

International outdoor athletics championships are typically hosted during the summer season, frequently in hot and humid climatic conditions. Therefore, we analyzed the association between apparent temperature and heat-related illnesses occurrence during international outdoor athletics championships and compared its incidence rates between athletics disciplines. Heat-related illnesses were selected from illness data prospectively collected at seven international outdoor athletics championships between 2009 and 2018 using a standardized methodology. The Universal Thermal Climate Index (UTCI) was calculated as a measure of the apparent temperature based on weather data for each day of the championships. Heat-related illness numbers and (daily) incidence rates were calculated and analyzed in relation to the daily maximum UTCI temperature and between disciplines. During 50 championships days with UTCI temperatures between 15℃ and 37℃, 132 heat-related illnesses were recorded. Average incidence rate of heat-related illnesses was 11.7 (95%CI 9.7 to 13.7) per 1000 registered athletes. The expected daily incidence rate of heat-related illnesses increased significantly with UTCI temperature (0.12 more illnesses per 1000 registered athletes/°C; 95%CI 0.08-0.16) and was found to double from 25 to 35°C UTCI. Race walkers (RR = 45.5, 95%CI 21.6-96.0) and marathon runners (RR = 47.7, 95%CI 23.0-98.8) had higher heat-related illness rates than athletes competing in short-duration disciplines. Higher UTCI temperatures were associated with more heat-related illnesses, with marathon and race walking athletes having higher risk than athletes competing in short-duration disciplines. Heat-related illness prevention strategies should predominantly focus on marathon and race walking events of outdoor athletics championships when high temperatures are forecast.

Youth running consensus statement: minimising risk of injury and illness in youth runners.

Despite the worldwide popularity of running as a sport for children, relatively little is known about its impact on injury and illness. Available studies have focused on adolescent athletes, but these findings may not be applicable to preadolescent and pubescent athletes. To date, there are no evidence or consensus-based guidelines identifying risk factors for injury and illness in youth runners, and current recommendations regarding suitable running distances for youth runners at different ages are opinion based. The International Committee Consensus Work Group convened to evaluate the current science, identify knowledge gaps, categorise risk factors for injury/illness and provide recommendations regarding training, nutrition and participation for youth runners.

Effects of Foam Rolling Duration on Tissue Stiffness and Perfusion: A Randomized Cross-Over Trial.

Despite its beneficial effects on flexibility and muscle soreness, there is still conflicting evidence regarding dose-response relationships and underlying mechanisms of foam rolling (FR). This study aimed to investigate the impact of different FR protocols on tissue perfusion and tissue stiffness. In a randomized crossover trial, two FR protocols (2x1 min, 2x3 min) were applied to the right anterior thigh of twenty healthy volunteers (11 females, 25 ± 4 years). Tissue perfusion (near infrared spectroscopy, NIRS) and stiffness (Tensiomyography, TMG and Myotonometry, MMT) were assessed before and after FR application. Variance analyses revealed a significant interaction of FR duration and tissue perfusion (F[1,19] = 7.098, p = 0.015). Local blood flow increased significantly from pre to post test (F[1,19] = 7.589, p = 0.013), being higher (Δ +9.7%) in the long-FR condition than in the short-FR condition (Δ +2.8%). Tissue stiffness (MMT) showed significant main effects for time (F[1,19] = 12.074, p = 0.003) and condition (F[1,19] = 7.165, p = 0.015) with decreases after short-FR (Δ -1.6%) and long-FR condition (Δ -1.9%). However, there was no time*dose-interaction (F[1,19] = 0.018, p = 0.895). No differences were found for TMG (p > 0.05). FR-induced changes failed to exceed the minimal detectable change threshold (MDC). Our data suggest that increased blood flow and altered tissue stiffness may mediate the effects of FR although statistical MDC thresholds were not achieved. Longer FR durations seem to be more beneficial for perfusion which is of interest for exercise professionals designing warm-up and cool-down regimes. Further research is needed to understand probable effects on parasympathetic outcomes representing systemic physiological responses to locally applied FR stimulations.

Epidemiology of injuries during the Wheelchair Basketball World Championships 2018: A prospective cohort study.

Several international sports federations have implemented a standardized injury reporting system during their championships. However, very few studies have investigated athletes with disabilities during major championships apart from the Paralympic Games. Therefore, the aim of this study was to assess the rate and characteristics of injuries during the Wheelchair Basketball World Championships 2018 (WBWC). This prospective cohort study was conducted during the WBWC held in Hamburg, Germany, from August 16 to August 26, 2018. Physicians or physiotherapists of all 28 participating teams (total 336 players) were asked to report all newly incurred injuries (with location, diagnosis, cause, and estimated duration of absence) daily on a standardized injury report form. Prevalence and incidence rates were calculated. Medical staff of 11 teams (132 players) reported 100 injuries, equivalent to 75.8 per 100 players (95% CI: 60.9-90.7) or 68.9 per 1000 player-days (55.4-82.4). Eight time-loss injuries were reported (6.1 injuries per 100 players [95% CI: 1.9-10.3] or 5.5 injuries per 1000 player-days [1.7-9.3]). More injuries were incurred during matches (n = 68) than during training. Most injuries affected the neck/cervical spine (16%), thoracic spine/upper back (15%), and shoulder (14%). The most frequent diagnosis was muscle spasms (25%), the most frequent cause was overuse (52%). A high rate of non-time-loss injuries compared to Paralympic Games was reported. Future studies should focus on the etiology of muscle spasms and further identify injury mechanisms of traumatic and overuse injuries in wheelchair basketball players to develop adequate preventive measures.

[Effects and sustainability of knee school : 2-year results of a secondary prevention program for gonarthrosis]. / Effekte und Nachhaltigkeit des Kniekollegs : 2-Jahres-Ergebnisse eines Sekundärpräventionsprogramms bei Gonarthrose.

BACKGROUND: Craftsmen and workers in the construction industry are at an increased risk of developing gonarthrosis due to their work-related burdens. In order to maintain the ability to work, occupational co-operative measures for secondary prevention can be carried out (BG Bau/Kniekolleg). The aim was to evaluate the efficacy after 2 years, depending on the degree of exercise adherence. MATERIAL AND METHODS: In a repeated measurement design (T1 before, T2 after knee school, T3 after 1 year, T4 after 2 years), 140 construction patients were assessed for their dynamic muscular strength (knee extension, 60°/s,); their quality of life (SF-36) and characteristics for gonarthrosis (WOMAC) were evaluated using analyses of variances, whereby one group trained after the knee training in the gym with instruction (Gr. 1 n = 63), one group completed a home-training program (Gr. 2 n = 38), and one group completed exercises outside of knee school (Gr.3 n = 39). RESULTS: For all parameters, significant acute efficacy and 2­year sustainability effects were observed (p ≤ 0.05, d: 0.2-0.8). There was no interaction with adherence during training after knee school (p > 0.05). CONCLUSION: Knee school has proved to be effective in the long term, leading to a critical questioning of future research, why there are no differences between guided, reduced or even missing long-term maintenance training.

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.

Spinal posture changes using dynamic rasterstereography during the modified Matthiass test discriminate between postural weak and strong healthy children (10-14 years): a pilot study.

The aim of this pilot study was to investigate whether the clinical Matthiass test can be objectified by means of dynamic rasterstereography in children. We aimed at discriminating between postural weak and strong children. Dynamic rasterstereography was used to capture sagittal spinal posture changes during the modified Matthiass test (mMT). Primary outcomes were spinal posture changes (trunk inclination, kyphotic and lordotic angles) during the test. Two-step cluster analysis was run jointly on the three primary outcomes. Data of 101 healthy children (10-14 years, 46% girls) were assessed. Cluster analysis identified two groups of participants with significantly different postural performance levels during the mMT (low vs. high performers). Low performers showed a higher increase in backward lean, as well as kyphosis and lordosis (4°-5°, respectively) when compared to high performers. The two performance groups were age-, BMI-, and activity-matched.Conclusion: This pilot study established preliminary normative data on spinal posture changes during the Matthiass test (high performers) and provided corresponding cutoff values for postural weakness (low performers). These results could provide a basis for future longitudinal and interventional studies targeting long-term consequences of childhood postural weakness and the prevention of back pain. What is Known: • The prevalence of postural insufficiencies in children is high. • No consensus exists about the postural assessment in children. • A common clinical test to identify postural insufficiency is the Matthiass test yet criticized for its subjective assessment. What is New: • This pilot study objectified the modified Matthiass test by rasterstereography and statistically identified two groups of healthy children with different postural performance levels. • It established preliminary normative data on spinal posture changes and provided corresponding cutoff values for postural weakness.

Effects of barefoot and footwear conditions on learning of a dynamic balance task: a randomized controlled study.

PURPOSE: Although barefoot balancing has shown to be more challenging compared to shod balancing, it is still unclear whether this may also influence the balance learning effects. The purpose of this study was to explore the impact of barefoot and shod exercising on learning of a dynamic balance task. METHODS: Sixty healthy and physically active adults (mean age 25.3 ± 3.4 years) were randomly allocated into one of three groups (barefoot, shod and controls). The barefoot and shod intervention groups exercised once weekly over 7 weeks on a stability platform with an unstable surface. Each training session included 15 trials over 30 s. Before and after the intervention period, all participants completed two balance tests (stability platform and Balance Error Scoring System = BESS) under barefoot and shod conditions. Group effects in stability gains (pre to post-test differences) were analysed using ANOVA. Development of balance learning curves during the intervention period was analysed using a mixed effects model. RESULTS: Balance times improved in both intervention groups (p < 0.001, 95% CI barefoot 5.82-9.22 s, shod 7.51-10.92 s) compared to controls. The barefoot intervention group showed a significantly less sloped balance learning curve compared to the shod intervention group (p = 0.033). No changes over time or differences between groups were found for the BESS test. CONCLUSIONS: Improvements in the dynamic balance task did not differ between individuals exercising barefoot or with footwear although the progression was slower in the barefoot group. The lack of changes in the BESS supports the task-specificity of balance learning effects.

Epidemiology of injuries in outdoor and indoor hockey players over one season: a prospective cohort study.

OBJECTIVES: To determine the incidence and characteristics of hockey ('field hockey') injuries over the course of one outdoor and indoor season. Comparisons of female versus male players, outdoor versus indoor season and match versus practice were performed. METHODS: Female and male teams of the first, second, third, regional and youth divisions were recruited among a local hockey association in Northern Germany, and followed over an indoor and an outdoor season. Exposure times and location, type, severity and cause of injuries during practice and matches were documented by the coaches or medical staff and collected weekly. Prevalence and incidence rates were calculated. RESULTS: Of the 232 players (mean±SD age 20.7±4.7 years, 68.1% male, 31.9% first division), 84 players (36.2%) suffered 108 new injuries during the season. The overall incidence rate was 3.7 injuries per 1000 player hours (95% CI 3.0 to 4.4). The injury incidence was lower in practice (2.7 per 1000 player practice hours, 95% CI 2.0 to 3.3) than in matches (9.7 per 1000 player match hours, 95% CI 6.8 to 12.7), and was similar for female and male players as well as during the outdoor and the indoor season. Most injuries affected the lower limb (thigh, knee and ankle) and occurred without contact (58.3%). Severe injuries (n=34; 31.5%) were predominantly located at the knee and hand/finger. CONCLUSION: Hockey players have a high prevalence and incidence of injuries, especially at the lower limb.