Dirk-Wouter Smits

The Preventive Effect of the Nordic Hamstring Exercise on Hamstring Injuries in Amateur Soccer Players A Randomized Controlled Trial

Background: Hamstring injuries are the most common muscle injuries in soccer, and they have a high rate of recurrence. Eccentric hamstrings strength is recognized as an important modifiable risk factor. This led to the development of prevention exercises such as the nordic hamstring exercise (NHE). The effectiveness of the NHE on hamstring injury prevention has never been investigated in amateur soccer. Purpose: To investigate the preventive effect of the NHE on the incidence and severity of hamstring injuries in male amateur soccer players. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: Male amateur soccer players (age, mean ± SD, 24.5 ± 3.8 years) from 40 teams were randomly allocated to an intervention (n = 20 teams, 292 players) or control group (n = 20 teams, 287 players). The intervention group was instructed to perform 25 sessions of NHE in a 13-week period. Both the intervention and control groups performed regular soccer training and were followed for hamstring injury incidence and severity during the 2013 calendar year. At baseline, personal characteristics (eg, age, injury history, field position) were gathered from all participants via a questionnaire. Primary outcome was injury incidence. Secondary outcomes were injury severity and compliance with the intervention protocol. Results: A total of 38 hamstring injuries were recorded, affecting 36 of 579 players (6.2%). The overall injury incidence rate was 0.7 (95% CI, 0.6-0.8) per 1000 player hours, 0.33 (95% CI, 0.25-0.46) in training, and 1.2 (95% CI, 0.82-1.94) in matches. Injury incidence rates were significantly different between the intervention (0.25; 95% CI, 0.19-0.35) and control groups (0.8; 95% CI, 0.61-1.15), χ2(1, n = 579) = 7.865; P = .005. The risk for hamstring injuries was reduced in the intervention group compared with the control group (odds ratio, 0.282; 95% CI, 0.110-0.721) and was statistically significant (P = .005). No statistically significant differences were identified between the intervention and control groups regarding injury severity. Compliance with the intervention protocol was 91%. Conclusion: Incorporating the NHE protocol in regular amateur training significantly reduces hamstring injury incidence, but it does not reduce hamstring injury severity. Compliance with the intervention was excellent.

Development of daily activities in school-age children with cerebral palsy

The purpose of this study was to describe the course of capabilities in self-care, mobility, and social function in school-age children with cerebral palsy (CP) and to investigate associations with CP-, child-, and family-characteristics. A clinic-based sample of children with CP (n = 116; 76 males, 40 females; mean age 6 y 3 mo, SD 12 mo) was followed longitudinally in three yearly measurements. Childrens capabilities were assessed with the Pediatric Evaluation of Disability Inventory Functional Skills Scale (PEDI-FSS). Averaged for the total group, significant increases over time were shown in PEDI-FSS scores in all three domains. For self-care, the course was best predicted by a model including level of gross motor function (measured by the Gross Motor Function Classification System) and intellectual capacity (measured by Ravens Coloured Progressive Matrices). For mobility, the course was best predicted by a model containing only level of gross motor function. For social function, the course was best predicted by a model comprising level of bimanual function (measured by the Manual Ability Classification System) and paternal educational level. Generally, the increase in capabilities was greater if level of functioning was higher, except for level of paternal education. The findings indicate that there are different sets of determinants for the course of different domains of daily activities. Such different sets of determinants may help to set realistic expectations and to create appropriate treatment plans for different domains of daily activities in school-age children with CP.

Relationship between gross motor capacity and daily‐life mobility in children with cerebral palsy

Aim  The aim of this study was to examine the relationship between gross motor capacity and daily‐life mobility in children with cerebral palsy (CP) and to explore the moderation of this relationship by the severity of CP.

Developmental Trajectories of Daily Activities in Children and Adolescents With Cerebral Palsy

OBJECTIVES: To describe the developmental trajectories of mobility performance and daily activities in children and young adults with cerebral palsy (CP). To explore the influence of gross motor function and intellectual disability on these trajectories. METHODS: Four hundred and twenty-four Dutch participants with CP (aged 1–20 years at study onset) were followed yearly over a period of 2 to 4 years. Developmental trajectories (from ages 1–16 years) were described for mobility performance and performance of daily activities, assessed by using the Vineland Adaptive Behavior Scale for gross motor function (classified by the Gross Motor Function Classification System) and intellectual disability (by IQ or school type). A subanalysis was done for performance of daily activities in a subgroup of participants without intellectual disability (aged 1–24 years). RESULTS: The developmental trajectories of mobility performance differed according to levels of gross motor function but not levels of intellectual disability. Intellectual disability affected the performance of daily activities, with lower overall trajectory levels for participants with intellectual disabilities. For participants without intellectual disability, high-level developmental trajectories were found, with values similar to those of typically developing children despite differences in gross motor function level. CONCLUSIONS: Mobility performance is determined mainly by levels of gross motor function. For performance of daily activities, intellectual disability was a more important determinant. Participants without intellectual disability showed developmental trajectories approaching values for typically developing participants. These estimated trajectories can guide rehabilitation interventions and future expectations for children and young adults with CP.

Development of non-verbal intellectual capacity in school-age children with cerebral palsy

BACKGROUND Children with cerebral palsy (CP) are at greater risk for a limited intellectual development than typically developing children. Little information is available which children with CP are most at risk. This study aimed to describe the development of non-verbal intellectual capacity of school-age children with CP and to examine the association between the development of non-verbal intellectual capacity and the severity of CP. METHODS A longitudinal analysis in a cohort study was performed with a clinic-based sample of children with CP. Forty-two children were assessed at 5, 6 and 7 years of age, and 49 children were assessed at 7, 8 and 9 years of age. Non-verbal intellectual capacity was assessed by Ravens Coloured Progressive Matrices (RCPM). Severity of CP was classified by the Gross Motor Function Classification System, type of motor impairment and limb distribution. manova for repeated measurements was used to analyse time effects and time × group effects on both RCPM raw scores and RCPM intelligence quotient scores. RESULTS The development of non-verbal intellectual capacity was characterised by a statistically significant increase in RCPM raw scores but no significant change in RCPM intelligence quotient scores. The development of RCPM raw scores was significantly associated with the severity of CP. Children with higher levels of gross motor functioning and children with spastic CP showed greater increase in raw scores than children with lower levels of gross motor functioning and children with dyskinetic CP. CONCLUSIONS Children with CP aged between 5 and 9 years show different developmental trajectories for non-verbal intellectual capacity, which are associated with the severity of CP. The development of non-verbal intellectual capacity in children with less severe CP seems to resemble that of typically developing children, while children with more severe CP show a limited intellectual development compared to typically developing children.

Arithmetic performance of children with cerebral palsy: The influence of cognitive and motor factors

Children diagnosed with cerebral palsy (CP) often show difficulties in arithmetic compared to their typically developing peers. The present study explores whether cognitive and motor variables are related to arithmetic performance of a large group of primary school children with CP. More specifically, the relative influence of non-verbal intelligence, working memory, word decoding capacities, gross- and fine motor skills on arithmetic performance is examined using structural equation modeling. One-hundred sixteen primary school children with a formal diagnosis of CP participated (76 males, M = 7; 3 years, SD = 3 months). In agreement with previous studies our results showed that the cognitive and motor predictors were all positively correlated to each other. Furthermore, in the cognitive model, non-verbal intelligence and word decoding were related to arithmetic in primary school. Our combined model (that included both motor and cognitive variables) showed that word decoding and fine motor skills were the strongest predictors of arithmetic performance. To conclude, this study was the first to show the influence of word decoding and fine motor skills on arithmetic performance of children with CP.

How Do Changes in Motor Capacity, Motor Capability, and Motor Performance Relate in Children and Adolescents With Cerebral Palsy?

OBJECTIVE To investigate the relations between changes in motor capacity (can do, in standardized environment), motor capability (can do, in daily environment), and motor performance (does do, in daily environment) among children with cerebral palsy (CP). DESIGN Prospective longitudinal study. After baseline measurements (at the age of 18 mo, 30 mo, 5 y, 7 y, 9 y, 11 y, or 13 y), 2-year follow-up measurements were performed. Change scores were calculated, and Pearson correlations were used for change score relations. SETTING Outpatient clinic. PARTICIPANTS Toddlers, school-age children, and adolescents with CP (N=321; 200 boys, 121 girls). Levels of severity according to the Gross Motor Function Classification System included level I (42%), level II (15%), level III (17%), level IV (13%), and level V (13%). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Change in motor capacity was assessed with the Gross Motor Function Measure-66. Changes in motor capability and motor performance were assessed with the Pediatric Evaluation of Disability Inventory using the Functional Skills Scale and Caregiver Assistance Scale, respectively. RESULTS Within the total group, change score correlations were moderate (.52-.67) and significant (P<.001). For age groups, correlations were significantly higher in toddlers than school-age children and adolescents. For severity levels, correlations were significantly higher in children at level III than level I, IV, and V. CONCLUSIONS Results imply that change in motor capacity does not automatically translate to change in motor capability and change in motor capability does not automatically translate to change in motor performance. Results also show different relations for clinically relevant subgroups. These are important insights for clinical practice because they can guide evidence-based interventions with a focus on activities.

The NLstart2run study: health effects of a running promotion program in novice runners, design of a prospective cohort study

BackgroundRunning is associated with desirable lifestyle changes. Therefore several initiatives have been undertaken to promote running. Exact data on the health effects as a result of participating in a short-term running promotion program, however, is scarce. One important reason for dropout from a running program is a running-related injury (RRI). The incidence of RRIs is high, especially in novice runners. Several studies examined potential risk factors for RRIs, however, due to the often underpowered studies it is not possible to reveal the complex mechanism leading to an RRI yet.The primary objectives are to determine short- and long-term health effects of a nationwide “Start to Run” program and to identify determinants for RRIs in novice runners. Secondary objectives include examining reasons and determinants for dropout, medical consumption and economical consequences of RRIs as a result of a running promotion program.Methods/designThe NLstart2run study is a multi-center prospective cohort study with a follow-up at 6, 12, 24 and 52 weeks. All participants that sign up for the Start to Run program in 2013, which is offered by the Dutch Athletics Federation, will be asked to participate in the study.During the running program a digital running log will be completed by the participants every week to administer exposure and running related pain. After the running program the log will be completed every second week. An RRI is defined as any musculoskeletal ailment of the lower extremity or back that the participant attributed to running and hampers running ability for at least one week.DiscussionThe NLstart2run study will provide insight into the short- and long-term health effects as a result of a short-term running promotion program. Reasons and determinants for dropout from a running promotion program will be examined as well. The study will result in several leads for future RRI prevention and as a result minimize dropout due to injury. This information may increase the effectiveness of future running promotion programs and will thereby contribute positively to public health.Trial registrationThe Netherlands National Trial Register NTR3676. The NTR is part of the WHO Primary Registries.

Longitudinal development of gross motor function among Dutch children and young adults with cerebral palsy: an investigation of motor growth curves

The aim of this study was to describe patterns for gross motor development by level of severity in a Dutch population of individuals with cerebral palsy (CP).

The NLstart2run study: Incidence and risk factors of running-related injuries in novice runners

Running is a popular form of physical activity, despite of the high incidence of running‐related injuries (RRIs). Because of methodological issues, the etiology of RRIs remains unclear. Therefore, the purposes of the study were to assess the incidence of RRIs and to identify risk factors for RRIs in a large group of novice runners. In total, 1696 runners of a 6‐week supervised “Start to Run” program were included in the NLstart2run study. All participants were aged between 18 and 65, completed a baseline questionnaire that covered potential risk factors, and completed at least one running diary. RRIs were registered during the program with a weekly running log. An RRI was defined as a musculo‐skeletal complaint of the lower extremity or back attributed to running and hampering running ability for three consecutive training sessions. During the running program, 10.9% of the runners sustained an RRI. The multivariable Cox regression analysis showed that a higher age, higher BMI, previous musculo‐skeletal complaints not attributed to sports and no previous running experience were related to RRI. These findings indicate that many novice runners participating in a short‐term running program suffer from RRIs. Therefore, the identified risk factors should be considered for screening and prevention purposes.