Innate talent in sport: from theoretical concept to complex reality – comment on Baker & Wattie

Over the last 20 years, the concept of innate talent has been discussed in the literature, and different factors have been associated with talent in different sports. However, it should be noted that talent identification is sport-, or even position-specific, and no ‘one size fits all’ consensus can be established. Specific talent profiles should be developed, acknowledging the multidimensionality of talent by taking physical, physiological, cognitive, psychological, and motivational factors into account. These profiles should also be age-specific and adjusted for covariates such as maturational timing and training history. To make a step forward in talent identification, we should not only move ahead in identifying innate talent, but also acknowledge the multifaceted and dynamic nature of talent. Therefore, we recommend researchers and practitioners to start approaching talent as a multidimensional, complex system

Injury characteristics in children's football and perspectives for prevention

Sport and physical activity for children is widely recommended to support a healthy lifestyle. Football is the most popular sport worldwide. Given its popularity, football is an excellent setting to fulfil sufficient physical activity levels. Football can induce considerable beneficial health effects. However, injuries may be an unfortunate consequence of participating in sport. In light of the large number of players football injuries relate to a public health issue. Therefore, the application of suitable injury prevention seems indicated. Epidemiological data are required as a basis for the development of a tailored injury prevention programme. Our topical review on football injuries in child and adolescent players revealed a clear paucity of such data relating to the youngest age groups (players under 13 years of age). This PhD project envisaged four aims: • to quantify the efficacy of exercise-based injury prevention programmes in child and adolescent sport in general and with respect to different characteristics of the target group, the injury prevention programme, and the outcome variables. Therefore, we conducted a systematic review with meta-analysis. • to analyse the incidence and characteristics of football injuries in children aged 7 to 12 years in a large-scale prospective epidemiological study. • to analyse injury risk factors based on our prospective data. • to develop an age-specific injury prevention programme for children’s football and to test this programme regarding its feasibility and its effects on motor performance in a pilot study in 7 to 12 year old players. Injury prevention meta-analysis For our meta-analysis we conducted a systematic literature search in six databases and found 21 relevant studies. The original studies included a total of 27,561 athletes (median age 16.7 years; range 10.7 to 17.8). The overall injury rate ratio between intervention and control group was 0.54 (95%-confidence interval 0.45, 0.67), P < 0.001. Injury prevention programmes that included jumping/plyometric exercises showed a larger (P = 0.002) injury preventive effect than studies without such exercises. The results provide good evidence and clearly demonstrate beneficial effects of exercise-based injury prevention in youth sports. A practically relevant overall injury reduction of 46% has been observed. Based on these findings, in particular multimodal programmes including jumping/plyometric exercises can be recommended. However, there is a considerable lack of data for children (under 14 years of age). We concluded that future research should focus on these age-groups. Football injuries in children We conducted a prospective epidemiological study on injuries in children’s football over two seasons in Switzerland and the Czech Republic. Exposure of players during training and match play (in hours) and injury data were reported by coaches via an internet-based registration system. Location, type, and severity of injuries were classified according to an established consensus. We calculated injury incidence rates (injuries per 1,000 hours of football exposure). An injury was defined as any physical complaint sustained during a scheduled training session or match play resulting in at least one of the following: (1) inability to complete the current match or training session, (2) absence from subsequent training sessions or matches, and/or (3) injury requiring medical attention. We recorded 6,038 player-seasons with 395,295 hours of football exposure. The mean age of the players was 9.3 (SD 1.9) years, and 3.9% of the participants were girls. During the study period 417 injuries were reported. Most injuries (76%) were located in the lower limbs and 16% in the upper limbs. Joint and ligament injuries comprised 31%, contusions 23%, muscle and tendon injuries 19%, and fractures and bone injuries 15% of all injuries. About a quarter (24%) of all injuries led to more than 28 days of absence from sport participation and was therefore classified as “severe”. The overall injury incidence was 0.61 (95%-CI 0.53, 0.69) injuries per 1,000 hours of football exposure during training sessions and 4.57 (95%-CI 4.00, 5.23) during match play. Injury incidence rates increased with increasing age. A comparison between the findings of our prospective study on injuries in children’s football and our topical review (that mostly included older players) showed differences in injury patterns. Children sustained a relatively high proportion of fractures and bone stress and injuries to the upper limbs. This clearly underlines the necessity of an age-specific injury prevention programme for children’s football. Risk factors for football injuries This project aimed at investigating risk factors for football injuries in children. We analysed time-to-injury data of our prospective epidemiological study using standard as well as extended Cox models accounting for correlations on team- and intra-person-level. We analysed injury risk in relation to age, sex, playing position, preferred foot, and with regard to age-independent body height, body mass, and BMI. Further, we analysed injury risk in relation to playing surface. The overall injury risk was increased by 46% (P < 0.001) per year of life. Injury risk was higher in age-adjusted taller players (higher percentile-rank). Injury risk was increased on artificial turf (39%; P < 0.001) and lower during indoor sessions (32%; P < 0.001) compared to natural grass. Age is known as a risk factor from older players and was confirmed to be a risk factor in children’s football. The playing surface has been discussed earlier as a risk factor. However, latest generation turfs did not show an increased injury risk compared to natural grass in different studies on older (mostly high-level) players. Injury risk in relation to sex should be further investigated in future studies. Development of “FIFA 11+ Kids” Based on the gathered knowledge, we developed a tailored injury prevention programme for children’s football called “FIFA 11+ Kids” which takes age-specific injury patterns of the youngest players into account. “FIFA 11+ Kids” is a 15-minute warm-up programme. In its first version it consisted of 7 different exercises each with 3 levels (with increasing difficulty). The programme focuses on (1) spatial orientation, anticipation, and attention especially while dual-tasking (to avoid unintended contact with players or objects) (2) neuromuscular performance, body stability, and movement coordination (to prepare the body for the physical demands of playing football and to reduce the number of falls) and (3) appropriate falling techniques (to minimise the injury risk when falling). We slightly modified “FIFA 11+ Kids” based on the practical experiences during the pilot study. The main changes were 2 additional levels for each of the 7 exercises. “FIFA 11+ Kids” – motor performance (pilot study) We conducted a cluster-RCT (pilot study) to evaluate the feasibility of “FIFA 11+ Kids” and to test potential effects on motor performance in 7 to 12 year old children. We were interested in effects on motor performance, as effective injury prevention programmes generally influence modifiable risk factors (e.g. lack in balance, power or strength). We stratified 12 football teams (players aged 7 to 12 years) into an intervention (N = 56 players) and a control group (N = 67). The intervention group conducted the 15-min warm-up programme “FIFA 11+ Kids” twice a week for 10 weeks. The control group followed a standard warm-up (sham treatment). During pre- and post-tests we assessed parameters to determine balance, agility, power/strength, and football-specific skill/technique of the children. We used magnitude-based inferences and linear mixed-effects models to analyse the performance test results. We observed beneficial effects favouring the intervention group in dynamic balance, agility, jumping performance, and football-specific skill/technique. The observed improvements of motor performance indicate that “FIFA 11+ Kids” can positively influence intrinsic injury risk factors. Importantly, no negative side effects of the programme were observed. Coaches’ as well as players’ feedback regarding the feasibility of the programme were positive. Outlook: “FIFA 11+ Kids” prevents injuries In our subsequent large-scale cluster-RCT (that goes beyond the scope of the PhD project) “FIFA 11+ Kids” has proven to be efficacious in reducing injuries in children’s football. Considerable effects were found for overall, match, training, lower extremity, and specifically severe injuries. The observed overall injury reduction of 48% is comparable to studies in older youth football players (which we included in our meta-analysis). Based on these findings a broad implementation of “FIFA 11+ Kids” can be recommended to reduce injuries and to support the health benefits of playing football in the long term

Performance, stride characteristics, and muscle activity while running with a traditional compared to a newly developed running shoe

A new running shoe cushioning technology has been developed intending to dampen the landing impulse during running while allowing a powerful and direct push-off. We aimed to compare this newly developed technology to traditional running shoes in regard to endurance performance, spatiotemporal stride characteristics, ground reaction forces, and muscle activity. In a randomized crossover design, 13 recreational runners (age 24.9±1.2 years, height 1.68±0.07 m, body mass 62.8±6.0 kg, weekly running distance >30 km) were tested twice, once with their own traditional shoes and (with a 2-week run-in and a 6-week wash-out period) with shoes featuring the new technology. The two-day testing procedure consisted of a graded exercise running test to assess lactate threshold (LT) on day one. On the following day, muscle activity, ground reaction forces and spatiotemporal stride characteristics at two velocities (80% and 95% LT velocity) were recorded on an instrumented treadmill. Finally, 4 km time trial performance was assessed. Magnitude-based inferences were calculated to compare the two shoe conditions. Ground reaction force was likely higher at 95% LT (+5.7%) and possibly higher at 80% LT (+2.2%) with the newly designed shoes, while muscle activity was likely reduced in the tibialis anterior and biceps femoris muscles during push-off. Spatiotemporal stride parameters, physiological markers during the graded exercise test as well as time trial performance showed trivial or unclear differences between the conditions. The observed differences between the shoe conditions in ground reaction forces and muscle activity were insufficient to elicit improvements in selected performance parameters

Comparison of the ‘11+ Kids’ injury prevention programme and a regular warmup in children’s football (soccer) : a cost effectiveness analysis

Objective: To evaluate a potential reduction in injury related healthcare costs when using the '11+ Kids' injury prevention programme compared with a usual warmup in children's football. Methods: This cost effectiveness analysis was based on data collected in a cluster randomised controlled trial over one season from football teams (under-9 to under-13 age groups) in Switzerland. The intervention group (INT) replaced their usual warmup with '11+ Kids', while the control group (CON) warmed up as usual. Injuries, healthcare resource use and football exposure (in hours) were collected prospectively. We calculated the mean injury related costs in Swiss Francs (CHF) per 1000 hours of football. We calculated the cost effectiveness (the direct net healthcare costs divided by the net health effects of the '11+ Kids' intervention) based on the actual data in our study (trial based) and for a countrywide implementation scenario (model based). Results: Costs per 1000 hours of exposure were CHF228.34 (95% CI 137.45, 335.77) in the INT group and CHF469.00 (95% CI 273.30, 691.11) in the CON group. The cost difference per 1000 hours of exposure was CHF-240.66 (95% CI -406.89, -74.32). A countrywide implementation would reduce healthcare costs in Switzerland by CHF1.48 million per year. 1002 players with a mean age of 10.9 (SD 1.2) years participated. During 76 373 hours of football, 99 injuries occurred. Conclusion: The '11+ Kids' programme reduced the healthcare costs by 51% and was dominant (ie, the INT group had lower costs and a lower injury risk) compared with a usual warmup. This provides a compelling case for widespread implementation

A machine learning approach to assess injury risk in elite youth football players

Purpose To assess injury risk in elite-level youth football (soccer) players based on anthropometric, motor coordination and physical performance measures with a machine learning model. Methods A total of 734 players in the U10 to U15 age categories (mean age, 11.7 +/- 1.7 yr) from seven Belgian youth academies were prospectively followed during one season. Football exposure and occurring injuries were monitored continuously by the academies' coaching and medical staff, respectively. Preseason anthropometric measurements (height, weight, and sitting height) were taken and test batteries to assess motor coordination and physical fitness (strength, flexibility, speed, agility, and endurance) were performed. Extreme gradient boosting algorithms (XGBoost) were used to predict injury based on the preseason test results. Subsequently, the same approach was used to classify injuries as either overuse or acute. Results During the season, half of the players (n= 368) sustained at least one injury. Of the first occurring injuries, 173 were identified as overuse and 195 as acute injuries. The machine learning algorithm was able to identify the injured players in the hold-out test sample with 85% precision, 85% recall (sensitivity) and 85% accuracy (f1 score). Furthermore, injuries could be classified as overuse or acute with 78% precision, 78% recall, and 78% accuracy. Conclusions Our machine learning algorithm was able to predict injury and to distinguish overuse from acute injuries with reasonably high accuracy based on preseason measures. Hence, it is a promising approach to assess injury risk among elite-level youth football players. This new knowledge could be applied in the development and improvement of injury risk management strategies to identify youth players with the highest injury risk

Predicting fever in neutropenia with safety-relevant events in children undergoing chemotherapy for cancer: The prospective multicenter SPOG 2015 FN Definition Study.

BACKGROUND Fever in neutropenia (FN) remains a frequent complication in pediatric patients undergoing chemotherapy for cancer. Preventive strategies, like primary antibiotic prophylaxis, need to be evidence-based. PROCEDURE Data on pediatric patients with any malignancy from the prospective multicenter SPOG 2015 FN Definition Study (NCT02324231) were analyzed. A score predicting the risk to develop FN with safety-relevant events (SRE; bacteremia, severe sepsis, intensive care unit admission, death) was developed using multivariate mixed Poisson regression. Its predictive performance was assessed by internal cross-validation and compared with the performance of published rules. RESULTS In 238 patients, 318 FN episodes were recorded, including 53 (17%) with bacteremia and 68 (21%) with SRE. The risk-prediction score used three variables: chemotherapy intensity, defined according to the expected duration of severe neutropenia, time since diagnosis, and type of malignancy. Its cross-validated performance, assessed by the time needed to cover (TNC) one event, exceeded the performance of published rules. A clinically useful score threshold of ≥11 resulted in 2.3% time at risk and 4.1 months TNC. Using external information on efficacy and timing of intermittent antibiotic prophylaxis, 4.3 months of prophylaxis were needed to prevent one FN with bacteremia, and 5.2 months to prevent one FN with SRE, using a threshold of ≥11. CONCLUSIONS This score, based on three routinely accessible characteristics, accurately identifies pediatric patients at risk to develop FN with SRE during chemotherapy. The score can help to design clinical decision rules on targeted primary antibiotic prophylaxis and corresponding efficacy studies

Accuracy of maturity prediction equations in individual elite football players

Background Equations predicting age at peak height velocity (APHV) are often used to assess somatic maturity and to adjust training load accordingly. However, information on the intra-individual accuracy of APHV in youth athletes is not available. Aim The purpose of this study is to assess the accuracy of predication equations for the estimation of APHV in individual youth male football players. Subjects and methods Body dimensions were measured at least every three months in 17 elite youth male football players (11.9 +/- 0.8 years at baseline) from the 2008-2009 through the 2011-2012 seasons. APHV was predicted at each observation with four suggested equations. Predicted APHV was compared to the player's observed APHV using one-sample-t-tests and equivalence-tests. Longitudinal stability was assessed by comparing the linear coefficient of the deviation to zero. Results Predicted APHV was equivalent to the observed APHV in none of the players. A difference with a large effect size (Cohen'sd > 0.8) was noted in 87% of the predictions. Moreover, predictions were not stable over time in 71% of the cases. Conclusions None of the evaluated prediction equations is accurate for estimating APHV in individual players nor are predictions stable over time, which limits their utility for adjusting training programmes

Self-reported life-space mobility in the first year after ischemic stroke: longitudinal findings from the MOBITEC-Stroke project

Background Life-space mobility is defined as the size of the area in which a person moves about within a specified period of time. Our study aimed to characterize life-space mobility, identify factors associated with its course, and detect typical trajectories in the first year after ischemic stroke. Methods MOBITEC-Stroke (ISRCTN85999967; 13/08/2020) was a cohort study with assessments performed 3, 6, 9 and 12 months after stroke onset. We applied linear mixed effects models (LMMs) with life-space mobility (Life-Space Assessment; LSA) as outcome and time point, sex, age, pre-stroke mobility limitation, stroke severity (National Institutes of Health Stroke Scale; NIHSS), modified Rankin Scale, comorbidities, neighborhood characteristics, availability of a car, Falls Efficacy Scale-International (FES-I), and lower extremity physical function (log-transformed timed up-and-go; TUG) as independent variables. We elucidated typical trajectories of LSA by latent class growth analysis (LCGA) and performed univariate tests for differences between classes. Results In 59 participants (mean age 71.6, SD 10.0 years; 33.9% women), mean LSA at 3 months was 69.3 (SD 27.3). LMMs revealed evidence (p ≤ 0.05) that pre-stroke mobility limitation, NIHSS, comorbidities, and FES-I were independently associated with the course of LSA; there was no evidence for a significant effect of time point. LCGA revealed three classes: “low stable”, “average stable”, and “high increasing”. Classes differed with regard to LSA starting value, pre-stroke mobility limitation, FES-I, and log-transformed TUG time. Conclusion Routinely assessing LSA starting value, pre-stroke mobility limitation, and FES-I may help clinicians identify patients at increased risk of failure to improve LSA

Performance, stride characteristics, and muscle activity while running with a traditional compared to a newly developed running shoe

A new running shoe cushioning technology has been developed intending to dampen the landing impulse during running while allowing a powerful and direct push-off. We aimed to compare this newly developed technology to traditional running shoes in regard to endurance performance, spatiotemporal stride characteristics, ground reaction forces, and muscle activity. In a randomized crossover design, 13 recreational runners (age 24.9±1.2 years, height 1.68±0.07 m, body mass 62.8±6.0 kg, weekly running distance >30 km) were tested twice, once with their own traditional shoes and (with a 2-week run-in and a 6-week wash-out period) with shoes featuring the new technology. The two-day testing procedure consisted of a graded exercise running test to assess lactate threshold (LT) on day one. On the following day, muscle activity, ground reaction forces and spatiotemporal stride characteristics at two velocities (80% and 95% LT velocity) were recorded on an instrumented treadmill. Finally, 4 km time trial performance was assessed. Magnitude-based inferences were calculated to compare the two shoe conditions. Ground reaction force was likely higher at 95% LT (+5.7%) and possibly higher at 80% LT (+2.2%) with the newly designed shoes, while muscle activity was likely reduced in the tibialis anterior and biceps femoris muscles during push-off. Spatiotemporal stride parameters, physiological markers during the graded exercise test as well as time trial performance showed trivial or unclear differences between the conditions. The observed differences between the shoe conditions in ground reaction forces and muscle activity were insufficient to elicit improvements in selected performance parameters

Psychometric properties of the MOBITEC-GP mobile application for real-life mobility assessment in older adults

Aim of this study was to test the reliability and validity of the life-space measures and walking speed delivered by the MOBITEC-GP app. Participants underwent several supervised walking speed assessments as well as a 1-week life-space assessment during two assessment sessions 9 days apart. Fifty-seven older adults (47.4% male, mean age= 75.3 (±5.9) years) were included in the study. The MOBITEC-GP app showed moderate to excellent test-retest reliability (ICCs between 0.584 and 0.920) and validity (ICCs between 0.468 and 0.950) of walking speed measurements of 50 meters and above and of most 1-week life-space parameters, including life-space area, time spent out-of-home, and action range. The MOBITEC-GP app for Android is a reliable and valid tool for the assessment of real-life walking speed (at distances of 50 metres and above) and life-space parameters of older adults. Future studies should look into technical issues more systematically in order to avoid invalid measurements