Monique A.M. Berger

Hydrodynamic drag and lift forces on human hand/arm models

Forces acting on the forearm and hand during swimming can be decomposed into drag forces and lift forces. In this study drag and lift forces were measured on two models of a human hand and forearm when towed in a towing tank. To compare the results of models with different size at different velocities force data were normalized to drag and lift coefficients (Cd and Ct). Influence of the orientation of the model with respect to the flow, velocity, size of the model and the relative contribution of the hand and forearm on Cd and Ct were studied. The orientation of the model with respect to the line of motion was varied by rotating the models around three axes, and quantified using the angle of pitch (AP: the angle between the hand plane and flow) and the sweep-back angle (SB: the orientation of the flow vector when projected on the hand plane). Cd was maximal when the palm of the hand is almost perpendicular to the flow (AP = 65 degrees, SB = 342 degrees). Ct shows maximal values at two different orientations: with the hand in a thumb-leading position, AP = 31 degrees, SB = 358 degrees, and with the hand in a little finger-leading position, AP = 48 degrees, SB = 193 degrees. The orientation of the hand was very critical in generating lift forces. By contrast, the influence of velocity and size of the model on the values of Cd and Ct was limited.(ABSTRACT TRUNCATED AT 250 WORDS)

Determining propulsive force in front crawl swimming: A comparison of two methods

To evaluate the propulsive forces in front crawl arm swimming, derived from a three-dimensional kinematic analysis, these values were compared with mean drag forces. The propulsive forces during front crawl swimming using the arms only were calculated using three-dimensional kinematic analysis combined with lift and drag coefficients obtained in fluid laboratories. Since, for any constant swimming speed, the mean propulsive force should be equal to the mean drag force acting on the body of the swimmer, mean values of the calculated propulsive forces were compared with the mean drag forces obtained from measurements on a Measuring Active Drag (MAD) system. The two methods yielded comparable results, the mean difference between them being only 5% (2 N). We conclude that propulsive forces obtained from three-dimensional kinematic analysis provide realistic values. The calculation of the propulsive force appears to be rather sensitive to the point on the hand at which the velocity is estimated and less sensitive to the orientation of the hand.

Technique and energy losses in front crawl swimming

Forces in human swimming consist of two components, a drag force and a lift force. The lift force is assumed to be beneficial because of the relative small energy loss to the water. This energy loss can be quantified by determining the propelling efficiency, ep (defined as the ratio of the useful power to the total power output). The first purpose of this study was to investigate whether high values of propelling efficiency can be explained by a relatively high contribution of lift and/or a favorable direction of the generated force in front crawl swimming. Propelling efficiency was estimated using two methods, one based on a physiological approach (epp) by measuring oxygen consumption and one based on a kinematic approach (epk) by calculating forces generated by hands and forearm and power components, from a three-dimensional analysis. The second purpose of this study was to compare epp and epk. The contribution of lift to the total force as well as the direction of the force cannot explain the values of epp. The values of epp and epk did not correlate significantly. In swimming propulsion some processes play a role which cannot be explained at this moment. One of these processes might be the generation of vortices.

Gaming supports youth with acquired brain injury? A pilot study

Aim: To explore the effects of usage of the Nintendo Wii on physical, cognitive and social functioning in patients with acquired brain injury (ABI). Methods: This multi-centre, observational proof-of-concept study included children, adolescents and young adults with ABI aged 6–29 years. A standardized, yet individually tailored 12-week intervention with the Nintendo Wii was delivered by trained instructors. The treatment goals were set on an individual basis and included targets regarding physical, mental and/or social functioning. Outcome assessments were done at baseline and after 12 weeks and included: the average number of minutes per week of recreational physical activity; the CAPE (Childrens Assessment of Participation and Enjoyment); the ANT (Amsterdam Neuropsychological Tasks); the achievement of individual treatment goals (Goal Attainment Scaling); and quality-of-life (PedsQL; Pediatric Quality of Life Inventory). Statistical analyses included paired t-tests or Wilcoxon-Signed-Rank tests. Results: Fifty patients were included (31 boys and 19 girls; mean age 17.1 years (SD = 4.4)), of whom 45 (90%) completed the study. Significant changes of the amount of physical activity, speed of information processing, attention, response inhibition and visual-motor coordination (p < 0.05) were seen after 12 weeks, whereas there were no differences in CAPE or PedsQL scores. Two-thirds of the patients reported an improvement of the main treatment goal. Conclusion: This study supports the potential benefits of gaming in children and youth with ABI.

Opportunities for measuring wheelchair kinematics in match settings; reliability of a three inertial sensor configuration

Knowledge of wheelchair kinematics during a match is prerequisite for performance improvement in wheelchair basketball. Unfortunately, no measurement system providing key kinematic outcomes proved to be reliable in competition. In this study, the reliability of estimated wheelchair kinematics based on a three inertial measurement unit (IMU) configuration was assessed in wheelchair basketball match-like conditions. Twenty participants performed a series of tests reflecting different motion aspects of wheelchair basketball. During the tests wheelchair kinematics were simultaneously measured using IMUs on wheels and frame, and a 24-camera optical motion analysis system serving as gold standard. Results showed only small deviations of the IMU method compared to the gold standard, once a newly developed skid correction algorithm was applied. Calculated Root Mean Square Errors (RMSE) showed good estimates for frame displacement (RMSE≤0.05 m) and speed (RMSE≤0.1m/s), except for three truly vigorous tests. Estimates of frame rotation in the horizontal plane (RMSE<3°) and rotational speed (RMSE<7°/s) were very accurate. Differences in calculated Instantaneous Rotation Centres (IRC) were small, but somewhat larger in tests performed at high speed (RMSE up to 0.19 m). Average test outcomes for linear speed (ICCs>0.90), rotational speed (ICC>0.99) and IRC (ICC> 0.90) showed high correlations between IMU data and gold standard. IMU based estimation of wheelchair kinematics provided reliable results, except for brief moments of wheel skidding in truly vigorous tests. The IMU method is believed to enable prospective research in wheelchair basketball match conditions and contribute to individual support of athletes in everyday sports practice.

Do field position and playing standard influence athlete performance in wheelchair basketball

ABSTRACT Improved understanding of mobility performance in wheelchair basketball is required to increase game performance. The aim of this study was to quantify the wheelchair-athlete activities of players in different field positions and of different playing standard during wheelchair basketball matches. From video analysis, absolute and relative duration and frequency of wheelchair movements and athlete control options were examined in 27 national standard and 29 international standard players during entire wheelchair basketball matches. Between-group factorial analysis of variances identified that national players drove more forward (42.6 ± 6.8 vs. 35.4 ± 3.7%; effect size Cohen’s d (ES) = 1.48) and started more often driving forward (33.9 ± 2.6 vs. 31.8 ± 2.8; ES = 0.77) during a match while the mean activity duration for a single driving forward activity was longer (4.3 ± 0.9 vs. 3.7 ± 0.6 s; ES = 0.75) than for international players. Furthermore, national players performed fewer rotational movements (21.8 ± 4.0 vs. 28.9 ± 7.8%; ES = –1.30) and started less often with the rotational movements (35.0 ± 3.6 vs. 40.5 ± 5.5; ES = –1.21) while the mean activity duration for a single rotation activity was shorter (2.1 ± 0.3 vs. 2.3 ± 0.3 s; ES = –0.67) than for international players. Differences in mobility performance among guard, forward and centre players were minimal. The results should help wheelchair basketball coaches specify wheelchair-handling training techniques and means to optimise wheelchair-athlete configurations.

The effects of an 8-week computer-based brain training programme on cognitive functioning, QoL and self-efficacy after stroke

ABSTRACT Cognitive impairment after stroke has a direct impact on daily functioning and quality of life (QoL) of patients and is associated with higher mortality and healthcare costs. The aim of this study was to determine the effect of a computer-based brain training programme on cognitive functioning, QoL and self-efficacy compared to a control condition in stroke patients. Stroke patients with self-perceived cognitive impairment were randomly allocated to the intervention or control group. The intervention consisted of an 8-week brain training programme (Lumosity Inc.®). The control group received general information about the brain weekly. Assessments consisted of a set of neuropsychological tests and questionnaires. In addition, adherence with trained computer tasks was recorded. No effect of the training was found on cognitive functioning, QoL or self-efficacy when compared to the control condition, except for very limited effects on working memory and speed. This study found very limited effects on neuropsychological tests that were closely related to trained computer tasks, but no transfers to other tests or self-perceived cognitive failures, QoL or self-efficacy. These findings warrant the need for further research into the value of computer-based brain training to improve cognitive functioning in the chronic phase after stroke.

Family impact of acquired brain injury in children and youth

Objective: To assess the parental view on the impact of pediatric traumatic brain injury (TBI) and nontraumatic brain injury (NTBI) on the family and its determinants. Methods: Follow-up study including parents of children with a hospital-based diagnosis of acquired brain injury (ABI) aged 4–20 years at onset of ABI. Parents completed the Pediatric Quality of Life Inventory Family Impact Module (PedsQL FIM), which measures Parent Health-Related Quality of Life, Family Functioning, Communication, and Worry. Additional assessments included the Pediatric Stroke Outcome Measure (PSOM), the Child & Family Follow-up Survey (CFFS), PedsQL General Core and Multiple Fatigue Scales, and sociodemographic and disease characteristics. Results: Parents of 108 patients, median age 13 years (range 5–22), completed the questionnaires 24–30 months after diagnosis. There were 81 patients with TBI of whom 11 (14%) with moderate/severe TBI and 27 patients with NTBI of whom 5 (19%) with moderate/severe NTBI. The median PedsQL FIM Total Scale was 80.4 (SD 16.1). The PedsQL FIM Total Scale and 4 out of 5 Subscale Scores were statistically significantly better in the TBI group than in the NTBI group and in patients with severe NTBI than with mild/moderate NTBI. Moreover, in the total group, there were significant univariate associations between the FIM Total Scale and/or one or more Subscale Scores and age, preinjury patient health problems, and the PSOM, CFFS, PedsQL General Core, and Multiple Fatigue Scales. In the multivariable analysis, the FIM Total Scale was significantly associated with type and severity of injury and preinjury patient health problems. Conclusions: Two years after onset, the parent-reported that impact of ABI on the family as measured by the PedsQL FIM was considerable especially in patients with moderate/severe NTBI.

Varying the Office Work Posture between Standing, Half-Standing and Sitting Results in Less Discomfort

In this study 10 subjects worked two weeks in their rather new normal work station and two weeks in another work station. These VDU workers were trained and received a table making standing work possible. They also received a chair making half sitting possible. The effects on experienced variation in posture and discomfort were studied. It appeared that most of the time people work in the normal sitting situation (69% in the new and 90% in the old work station). Sometimes the half sitting and standing posture was used in the new situation. This new situation had a significant lower discomfort in the back, neck and shoulder region compared with the old situation.

Psychometric evaluation of the Dutch language version of the Child and Family Follow-up Survey

Abstract Aim: The Child and Family Follow-up Survey (CFFS) is developed to monitor long-term outcomes of children and youth with acquired brain injury (ABI). The aim of this study was to translate and adapt it into the Dutch language and to evaluate its reliability and validity. Methods: The CFFS includes the Child and Adolescent Scale of Participation (CASP), the Child and Adolescent Factors Inventory (CAFI) and the Child and Adolescent Scale of Environment (CASE). The CFFS was translated into Dutch following international guidelines and adapted. The internal consistency, validity and test–retest reliability were examined among two groups of patients (n = 140 and n = 27) in the age of 5–22 years with ABI and their parents. Results: The translation and adaptation resulted in the CFFS-DLV, Dutch language version. The CASP-DLV, CAFI-DLV and CASE-DLV had a good internal consistency, with Cronbach’s alpha being 0.95, 0.89 and 0.83, respectively. There were statistically significant correlations among the three CFFS subscale scores. These scores were also significantly correlated with the total scores of the Pediatric Quality of Life Inventory (PedsQL, parent) and the Pediatric Stroke Outcome Measure, but not with the domain scores of the Children’s Assessment of Participation and Enjoyment (CAPE). The test–retest reliability was good to moderate, with the intra-class correlation coefficients being 0.90 for the CASP-DLV, 0.95 for the CAFI-DLV and 0.81 for the CASE-DLV. Conclusions: The CFFS-DLV, as translation and adaptation of the CFFS into Dutch, proved to be a promising instrument to measure long-term outcomes of children and youth with ABI. Further research is needed to examine its responsiveness to change and potential in other patient groups.