Jan Seghers

Posture, muscle activity and muscle fatigue in prolonged VDT work at different screen height settings

With the increasing use of video display terminals (VDTs), there is growing concern over the corresponding increase in the number of health problems reported. Although much research has focused on identifying the optimal screen height, there is to date no consensus. This study aimed to investigate the effect of prolonged (89 min) VDT work at four different screen heights on head-neck posture, muscle activity and the development of muscle fatigue. The results show that lowering screen height, starting from 15 cm above the baseline (i.e. top of the screen level with eye height while sitting), decreased the ear-eye angle, increased the viewing angle, increased the viewing angle relative to the ear-eye line, and increased the muscle activity of the neck extensor muscles. There were also some significant time effects on postural angles and muscle activity. In this study there were only rare occurrences of muscle fatigue, defined as a simultaneous increase in EMG amplitude and a shift of the EMG power spectrum to lower frequencies. Muscle activity increased significantly in some muscles and for certain screen heights.

Validation of the wavelet spectral estimation technique in Biceps Brachii and Brachioradialis fatigue assessment during prolonged low-level static and dynamic contractions

An experiment was carried out to investigate the myoelectrical manifestations of fatigue of the Biceps Brachii and Brachioradialis muscles in low-level (15% MVC) prolonged isometric and dynamic contractions. The range of the joint angle was 70-110 degrees and the mean speed of flexion and extension was about 33.33 degrees /s (1.2 s for 40 degrees ). The use of Wavelet transform (IMNF) in weakly stationary dynamic SEMG signals was validated in comparison with the Fourier transform (MPF). The development of fatigue and its myoelectrical manifestations (increase in RMS and decrease in mean frequency) in dynamic contractions show no deviations from what is found in literature for both spectral estimation techniques. The benefit of Wavelets is its future use in non-stationary conditions. Lower IMNF slopes in dynamic compared to isometric contractions for Biceps Brachii might be an indication that wavelets reflect more the changes in muscle fiber propagation velocity. The results of the use of Wavelet transform in detecting frequency modulations in different movement phases of the dynamic tests show that in the eccentric phase a systematic shift towards lower frequencies occurs. It also reveals the great possibilities of phase separation using Wavelets with high resolution and low interaction.

Bias in self-reported height and weight in preadolescents.

OBJECTIVES To examine the validity of self-reported height and weight and factors related to misreporting in preadolescents. The accuracy of screening for underweight (thinness), overweight, and obesity using self-reported data was also tested. STUDY DESIGN Self-reported height and weight was administered and then measured in 798 fourth graders age 8 to 11 years. Body mass index (BMI) was calculated from self-reported and measured data and BMI categories were determined using international age- and sex-specific BMI criteria. RESULTS Preadolescents overestimated their height by 0.54 ± 5.17 cm and underreported their weight by 0.80 ± 3.09 kg. BMI derived from self-reported data was underestimated by 0.47 ± 1.79 kg/m². Measured BMI category was an important independent predictor of bias in self-reported weight and BMI. Children who were overweight or obese underestimated their weight and BMI to a greater degree compared with normal weight/underweight children. The influence of sociodemographic factors on bias in self-reported values was relatively small. Approximately 15% of children were misclassified in BMI categories when self-reported data were used, especially in the underweight (thinness) and obese category. CONCLUSIONS Children age 8 to 11 years were not able to accurately estimate their actual height and weight, leading to erroneous estimating rates of their weight status.

Physical activity promotion in schools: which strategies do schools (not) implement and which socioecological factors are associated with implementation?

We studied the implementation and associated factors of strategies (e.g. sports after school and during lunch break, active schoolyards, active school commuting) and organizational principles (e.g. safe bike racks, pupil involvement) that facilitate the physical activity (PA)-promoting role of schools. Key representatives of 111 elementary and 125 secondary schools filled out an online survey. Less than half of the elementary schools organized sports during lunch-break or after school. In secondary schools the least implemented strategies were the promotion of active school commuting and after-school sports. In general pupil, parental and community involvement scored low. Better knowledge of community schools and having attended in-service training were associated with higher implementation scores in elementary and secondary schools. Better implementation of the strategies was found in larger schools. Participation in activities from the School Sports Association and more perceived interest from parents and the school board were also associated with higher implementation scores. In conclusion, knowledge of community schools and in-service training next to sufficient human resources are potential key factors to promote PA. Efforts are needed to convince and help schools to increase parental and pupil involvement and to build a policy on school-community partnerships.

A Framework for Physical Activity Programs within School-Community Partnerships.

School-community partnerships have shown their potential as incubators for innovations and for contributing to comprehensive physical activity (PA) programs. However, implementation frameworks for school-community partnerships that allow local tailoring of PA programs remain scarce. The present paper aims at documenting the composition of a framework for PA programs within schoolcommunity partnerships. The framework addresses socioecological strategies to promote extracurricular PA opportunities for pupils, which are integrated into five complementary components. To implement and reinforce the five components of the framework, involvement of schools, pupils, family, and community is facilitated by sustainable partnerships between these stakeholders. Partnerships are not only recommended on the school and community level, but also on a broader regional level that covers multiple communities. The development of the framework was an effort to integrate school-community partnerships into a flexible implementation framework for PA promotion. Implications of the framework for research agendas, professional education, and policy are formulated.

Youth sports clubs’ potential as health-promoting setting: Profiles, motives and barriers

Setting and Objective: For decades, the World Health Organisation has promoted settings-based health promotion, but its application to leisure settings is minimal. Focusing on organised sports as an important leisure activity, the present study had three goals: exploring the health promotion profile of youth sports clubs, identifying objective club characteristics (e.g. size, type of sport), predicting the presence/absence of health promotion in youth sports clubs and identifying perceived motives and barriers to health promotion in youth sports clubs, thereby improving the basis for policy guidelines. Method: Respondents were representatives from the board of 154 youth sports clubs. Data were collected through an online survey, including the health-promoting sports club index (HPSC-I). Linear regression and analysis of variance were used to identify predictors and differences. Results: Even though the motives were strongly supported, a majority of youth sports clubs were rated as low health promoting on the HPSC-I (59%). Overall, linear regression indicated that clubs founded more recently, offering multiple types of sports and offering both recreation and competition scored higher on the health promotion indices. Health promotion not being a priority of the board and lack of expertise were identified as the most important barriers. Conclusion: Progress is needed before youth sports clubs can truly be considered health-promoting settings. Policy suggestions are made to address the barriers, for example, financial incentives to maximise efforts and establishing collaborations between sports clubs and health promotion experts.

Is knee extension strength a better predictor of functional performance than handgrip strength among older adults in three different settings

BACKGROUND The first purpose was to examine whether knee extension strength is a better predictor of functional performance than handgrip strength among older adults (≥60 years). The second purpose was to identify functionally relevant cut-off values for muscle strength. METHODS 770 community-dwelling older adults, 104 older adults living in assisted living facilities and 73 nursing home residents were included. Static strength, expressed in kg/kg body weight (BW), was measured using two field tests: handgrip (GRIP/BW) and knee extension (KNEE/BW) test. Functional performance was assessed with 6-Minute Walk Distance (6MWD, N=947) and modified Physical Performance Test (mPPT, N=152). RESULTS Both GRIP/BW and KNEE/BW were positively correlated with functional performance in all settings (p<0.05). In the community and nursing homes, both strength variables equally contributed to functional performance. In assisted living facilities, KNEE/BW (R(2)6MWD=0.39 and R2mPPT=0.35) was clearly a better predictor of functional performance than GRIP/BW (R(2)6MWD=0.15 and R2mPPT=0.12). GRIP/BW had no added value to KNEE/BW in order to explain the variance in functional performance. Functionally relevant cut-off values for static strength, for men and women respectively, were set at 0.40 and 0.31 for KNEE/BW and at 0.43 and 0.31 for GRIP/BW. CONCLUSIONS Handgrip and knee extension strength are both important predictors of functional performance in older adults. In assisted living facilities only, knee extension strength was clearly more predictive than handgrip strength. Both cut-off values appear to be highly sensitive to screen for functionally relevant muscle weakness in older adults.

Piecing the puzzle together: case studies of international research in health-promoting sports clubs

This paper seeks to review the current international health-promoting sports club (HPSC) research, drawing together findings based on case studies from various countries to illustrate the status of HPSCs. In addition, future challenges for HPSC research and implementation are considered. The review includes six case studies from five countries. In summary, there are two major research themes in this area, namely ‘research into HPSC activity’ and ‘research into HPSC networks’. The first theme investigates the extent to which sports clubs and/or national sports organisations invest in health promotion (HP) – both in policy and practice. The latter theme is driven by an intention to widen the scope of HPSCs to reach novel internal actors, like parents, siblings, etc., and/or external non-sporting bodies, like communities, schools, etc. The future challenges for HPSC research require a better understanding of the motives, barriers and capacities of sports clubs and coaches. Sports organisations, clubs and coaches generally support the intent of the HPSC concept, but even with the best evidence- or theory-based HP programmes/guidelines/standards, nothing will happen in practice if the nature and capacities of sports clubs are not better acknowledged. Therefore, a call for embracing implementation science is finally made to enhance implementation.

Evaluation of a real world intervention using professional football players to promote a healthy diet and physical activity in children and adolescents from a lower socio-economic background: a controlled pretest-posttest design

BackgroundThe increasing rates of obesity among children and adolescents, especially in those from lower socio-economic backgrounds, emphasise the need for interventions promoting a healthy diet and physical activity. The present study aimed to examine the effectiveness of the ‘Health Scores!’ program, which combined professional football player role models with a school-based program to promote a healthy diet and physical activity to socially vulnerable children and adolescents.MethodsThe intervention was implemented in two settings: professional football clubs and schools. Socially vulnerable children and adolescents (n = 165 intervention group, n = 440 control group, aged 10-14 year) provided self-reported data on dietary habits and physical activity before and after the four-month intervention. Intervention effects were evaluated using repeated measures analysis of variance. In addition, a process evaluation was conducted.ResultsNo intervention effects were found for several dietary behaviours, including consumption of breakfast, fruit, soft drinks or sweet and savoury snacks. Positive intervention effects were found for self-efficacy for having a daily breakfast (p < 0.01), positive attitude towards vegetables consumption (p < 0.01) and towards lower soft drink consumption (p < 0.001). A trend towards significance (p < 0.10) was found for self-efficacy for reaching the physical activity guidelines. For sports participation no significant intervention effect was found. In total, 92 pupils completed the process evaluation, the feedback was largely positive.ConclusionsThe ‘Health Scores!’ intervention was successful in increasing psychosocial correlates of a healthy diet and PA. The use of professional football players as a credible source for health promotion was appealing to socially vulnerable children and adolescents.

Evaluation of a workplace intervention to promote commuter cycling: A RE-AIM analysis

BackgroundOriginating from the interdisciplinary collaboration between public health and the transportation field a workplace intervention to promote commuter cycling, ‘Bike to Work: cyclists are rewarded’, was implemented. The intervention consisted of two cycling contests, an online loyalty program based on earning ‘cycling points’ and the dissemination of information through folders, newsletters, posters and a website. The study purpose was to evaluate the dissemination efforts of the program and to gain insights in whether free participation could persuade small and middle-sized companies to sign up.MethodsThe RE-AIM framework was used to guide the evaluation. Two months after the start of the intervention a questionnaire was send to 4880 employees. At the end of the intervention each company contact person (n = 12) was interviewed to obtain information on adoption, implementation and maintenance.Comparison analyses between employees aware and unaware of the program were conducted using independent-samples t-tests for quantitative data and chi-square tests for qualitative data. Difference in commuter cycling frequency was assessed using an ANOVA test. Non-parametric tests were used for the comparison analyses between the adopting and non-adopting companies.ResultsIn total seven of the twelve participating companies adopted the program and all adopting companies implemented all intervention components. No significant differences were found in the mean number of employees (p = 0.15) or in the type of business sector (p = 0.92) between adopting and non-adopting companies. Five out of seven companies had the intention to continue the program. At the individual level, a project awareness of 65% was found. Employees aware of the program had a significantly more positive attitude towards cycling and reported significantly more commuter cycling than those unaware of the program (both p < 0.001). Participation was mainly because of health and environmental considerations.ConclusionsThe results of the dissemination study are promising. The adoption and implementation rates indicate that the ‘Bike to Work: cyclists are rewarded’ program seems to be a feasible workplace intervention. At the individual level, a higher score of commuter cycling was found among the employees aware of the program. Nevertheless, more evidence regarding long term effectiveness and sustainability of the intervention is needed.