Tracking of bone mass from childhood to puberty: a 7-year follow-up. The CHAMPS study DK

Bone mass in childhood is highly influenced by puberty. At the same age, bone mass was higher for pubertal than pre-pubertal children. A high level of tracking during 7 years from childhood through puberty was shown, indicating that early levels of bone mass may be important for later bone health.

INTRODUCTION

Bone mass development in childhood varies by sex and age, but also by pubertal stage. The objectives of this study were to (1) describe bone mass development in childhood as it relates to pubertal onset and to (2) determine the degree of tracking from childhood to adolescence.

METHODS

A longitudinal study with 7 years of follow-up was initiated in 2008 to include 831 children (407 boys) aged 8 to 17 years. Participants underwent whole body dual-energy X-ray absorptiometry (DXA) scanning, blood collection to quantify luteinizing hormone levels, and Tanner stage self-assessment three times during the 7-year follow-up. Total body less head bone mineral content, areal bone mineral density, and bone area were used to describe development in bone accrual and to examine tracking over 7 years.

RESULTS

Bone mass in pubertal children is higher than that of pre-pubertal children at the same age. Analysing tracking with quintiles of bone mass Z-scores in 2008 and 2015 showed that more than 80% of participants remained in the same or neighbouring quintile over the study period. Tracking was confirmed by correlation coefficients between Z-scores at baseline and 7-year follow-up (range, 0.80-0.84).

CONCLUSIONS

Bone mass is highly influenced by pubertal onset, and pubertal stage should be considered when examining children's bone health. Because bone mass indices track from childhood into puberty, children with low bone mass may be at risk of developing osteoporosis later in life.

Retinal vascular diameters in relation to physical activity in Danish children - The CHAMPS Eye Study

Our objective was to determine associations between retinal vascular caliber and physical activity (PA) in a school-based child cohort. In a prospective study, we created a childhood cumulative average PA-index using objectively measured PA (accelerometry) assessed at four periods between 2009 and 2015. Cumulative exposure to PA intensities was estimated. Cross-sectional examinations on biomarkers, anthropometry, and ophthalmological data including retinal fundus photographs were performed in 2015. Semi-automated measurements of retinal vascular diameters were performed and summarized into central retinal arteriolar and venular equivalents (CRAE, CRVE). We included 307 participants. Mean age in 2015 was 15.4 years (0.7). The mean CRAE and CRVE were 156.5 μm (2.8) and 217.6 μm (7.7), respectively. After adjusting for age, gender, and axial length, more time in PA was independently related to thinner retinal venules (β-coefficient = -1.25 μm/%, 95% confidence interval = -2.20, -0.30, P < .01). Sedentary time was associated with wider venules (P < .01). Furthermore, birthweight (β-coefficient = 0.56 μm/%, 95% confidence interval = 0.18, 0.95, P < .01) was associated with CRVE. Blood pressure was associated with thinner retinal arterioles (β-coefficient = -0.19 μm/mmHg, 95% confidence interval = -0.36, -0.01, P = .04). We concluded that children with higher PA in childhood had thinner retinal venular caliber. Our results suggest that PA during childhood positively impacts the retinal microcirculation and that retinal vascular analysis may be a possible assessment to detect microvascular impairments in children with an increased risk of future cardiovascular disease.

The inter- and intrarater reliability and agreement for field-based assessment of scapular control, shoulder range of motion, and shoulder isometric strength in elite adolescent athletes

OBJECTIVES

To investigate the intra- and interrater reliability and agreement for field-based assessment of scapular control, shoulder range of motion (ROM), and shoulder isometric strength in elite youth athletes.

DESIGN

Test-retest reliability and agreement study.

SETTING

Eight blinded raters (two for each assessment) assessed players on field during two testing sessions separated by one week.

PARTICIPANTS

162 elite youth handball players with or without a history of previous shoulder pain within the preceding six months.

MAIN OUTCOME MEASURES

Kappa (κ) and prevalence-adjusted bias-adjusted kappa (PABAK) coefficients for scapular control reliability, and 95% limits of agreement (LOA) for ROM and strength agreement.

RESULTS

Scapular control demonstrated substantial to almost perfect reliability (κ 0.67 to 0.84, PABAK from 0.68 to 0.88). Mean strength values ranged from 0.9 N/kg to 1.6 N/kg, and LOAs ranged from -0.7 N/kg to 0.8 N/kg. Rotational strength revealed additionally systematic bias between and within rater. No or acceptable systematic bias were evident for ROM and abduction strength measures. Mean values and LOAs for ROM ranged between 39.9° to 52.3°, and from -12.6° to 9.9°, respectively.

CONCLUSIONS

Scapular control and ROM can be assessed on the field with acceptable reliability. The threshold for reliable measurements of isometric strength using handheld-dynamometers is high.

The SMS, Phone, and medical Examination sports injury surveillance system is a feasible and valid approach to measuring handball exposure, injury occurrence, and consequences in elite youth sport

Current methods of sports injury surveillance are limited by lack of medical validation of self-reported injuries and/or incomplete information about injury consequences beyond time loss from sport. The aims of this study were to (a) evaluate the feasibility of the SMS, Phone, and medical Examination injury surveillance (SPEx) system (b) to evaluate the proportion of injuries and injury consequences reported by SPEx when compared to outcomes from a modified version of the Oslo Sports Trauma Research Centre (OSTRC) Overuse Injury Questionnaire. We followed 679 elite adolescent handball players over 31 weeks using the SPEx system. During the last 7 weeks, we also implemented a modified OSTRC questionnaire in a subgroup of 271 players via telephone interviews. The weekly response proportions to the primary SPEx questions ranged from 85% to 96% (mean 92%). SMS responses were received from 79% of the participants within 1 day. 95% of reported injuries were classified through the telephone interview within a week, and 67% were diagnosed by medical personnel. Comparisons between reported injuries from SPEx and OSTRC demonstrated fair (κ = 39.5% [25.1%-54.0%]) to substantial prevalence-adjusted bias-adjusted kappa (PABAK = 66.8% [95% CI 58.0%-75.6%]) agreement. The average injury severity score difference between SPEx and the OSTRC approach was -0.2 (95% CI -3.69-3.29) of possible 100 with 95% limits of agreement from(-14.81-14.41). These results support the feasibility and validity of the SPEx injury surveillance system in elite youth sport. Future studies should evaluate the external validity of SPEx system in different cohorts of athletes.

Validity of the SMS, Phone, and medical staff Examination sports injury surveillance system for time-loss and medical attention injuries in sports

The accurate measurement of sport exposure time and injury occurrence is key to effective injury prevention and management. Current measures are limited by their inability to identify all types of sport-related injury, narrow scope of injury information, or lack the perspective of the injured athlete. The aims of the study were to evaluate the proportion of injuries and the agreement between sport exposures reported by the SMS messaging and follow-up telephone part of the SMS, Phone, and medical staff Examination (SPEx) sports injury surveillance system when compared to measures obtained by trained on-field observers and medical staff (comparison method). We followed 24 elite adolescent handball players over 12 consecutive weeks. Eighty-six injury registrations were obtained by the SPEx and comparison methods. Of them, 35 injury registrations (41%) were captured by SPEx only, 10 injury registrations (12%) by the comparison method only, and 41 injury registrations (48%) by both methods. Weekly exposure time differences (95% limits of agreement) between SPEx and the comparison method ranged from -4.2 to 6.3 hours (training) and -1.5 to 1.0 hours (match) with systematic differences being 1.1 hours (95% CI 0.7 to 1.4) and -0.2 (95% CI -0.3 to -0.2), respectively. These results support the ability of the SPEx system to measure training and match exposures and injury occurrence among young athletes. High weekly response proportions (mean 83%) indicate that SMS messaging can be used for player measures of injury consequences beyond time-loss from sport. However, this needs to be further evaluated in large-scale studies.

Do number of days with low back pain and patterns of episodes of pain have similar outcomes in a biopsychosocial prediction model?

PURPOSES

We used two different methods to classify low back pain (LBP) in the general population (1) to assess the overlapping of individuals within the different subgroups in those two classifications, (2) to explore if the associations between LBP and some selected bio-psychosocial factors are similar, regardless which of the two classifications is used.

METHOD

During 1 year, 49- or 50-year-old people from the Danish general population were sent fortnightly automated text messages (SMS-Track) asking them if they had any LBP in the past fortnight. Responses for the whole year were then classified into two different ways: (1) In relation to the number of days with LBP in the preceding year (0, 1-30, and >30), (2) In relation to the frequency and duration of episodes of LBP (more or less never pain, episodic, and more or less constant pain). Some bio-psychosocial factors, collected with a questionnaire at baseline 9 years earlier, were entered into regression models to investigate their associations with the subgroups of the two classifications of LBP and the results compared.

RESULTS

The percentage of agreement between categories of the two classification systems was above 68 % (Kappa 0.7). Despite the large overlap of persons in the two classification groups, the patterns of associations with the two types of LBP definitions were different in the two classification groups. However, none of the estimates were significantly different when the variables were compared across the two classifications.

CONCLUSION

Different classification systems of LBP are capable of bringing forth different findings. This may help explain the lack of consistency between studies on risk factors of LBP.

Upper extremity injuries in Danish children aged 6-12, mechanisms, and risk factors

Although injuries to the upper extremity are most costly, the picture of the upper extremity injury problem remains incomplete. This study is the first to describe the etiology and mechanisms of upper extremity injuries in Danish children. A 2.5-year observational prospective cohort study was conducted to record upper extremity injuries in 1048 children. Data were weekly collected by sending a text message. A total of 176 upper extremity injuries were reported (128 acute injuries). Of the acute upper extremity injuries, 55% were sprains, 47% occurred in the hand/wrist, and 53% of cases were caused by a fall. When corrected for exposure to physical activity, this resulted in an acute upper extremity injury incidence density of 0.18 per 1000 h of physical activity. The odds of sustaining an upper extremity injury was higher in the older children (HR: 1.84, 95% CI: 1.10-3.09), a tendency was found suggesting that girls are at increased acute upper extremity risk compared to boys (HR: 1.40 95% CI: 0.97-2.04). The findings that most injuries occur after a fall, that injury risk increases over age and that girls seem to be at increased injury risk provides essential information to guide future childhood injury prevention.

Longitudinal influence of musculo-skeletal injuries and extra physical education on physical fitness in schoolchildren

The aims of this study were to investigate if (A) injuries and (B) increased physical education (PE) influenced the development of physical fitness in schoolchildren. Simultaneously, to investigate if a possible PE effect was modified by sport participation outside school hours. This was a longitudinal controlled school-based study. Six schools with 270 min of PE (extra PE) and four schools with 90 min of PE were followed up for 2.5 years. In total, 1054 children were included for analysis (normal PE = 443, extra PE = 611). Development in fitness was analyzed using composite z-scores from six fitness tests measured four times. Information of injury and sport was derived from weekly automated mobile phone text messages surveying the presence of musculo-skeletal pain and organized sport participation. Injury and extra PE both influenced the development of physical fitness. Injury decreased development of physical fitness with -1.01 composite z-score units (95% CI: -1.57; -0.45). Extra PE increased physical fitness development with 0.80 (95% CI: 0.49; 1.10) composite z-score units. The influence of injury was not dependent on extra PE. No modifying effect was found by mean weekly sport participation outside school hours. In conclusion, extra PE had a positive effect, whereas injuries had a negative effect on physical fitness development in schoolchildren.

Self-reported previous knee injury and low knee function increase knee injury risk in adolescent female football

Knee injuries are common in adolescent female football. Self-reported previous knee injury and low Knee injury and Osteoarthritis Outcome Score (KOOS) are proposed to predict future knee injuries, but evidence regarding this in adolescent female football is scarce. The aim of this study was to investigate self-reported previous knee injury and low KOOS subscale score as risk factors for future knee injuries in adolescent female football. A sample of 326 adolescent female football players, aged 15-18, without knee injury at baseline, were included. Data on self-reported previous knee injury and KOOS questionnaires were collected at baseline. Time-loss knee injuries and football exposures were reported weekly by answers to standardized text-message questions, followed by injury telephone interviews. A priori, self-reported previous knee injury and low KOOS subscale scores (< 80 points) were chosen as independent variables in the risk factor analyses. The study showed that self-reported previous knee injury significantly increased the risk of time-loss knee injury [relative risk (RR): 3.65, 95% confidence (CI) 1.73-7.68; P < 0.001]. Risk of time-loss knee injury was also significantly increased in players with low KOOS subscale scores (< 80 points) in Activities of Daily Living (RR: 5.0), Sport/Recreational (RR: 2.2) and Quality of Life (RR: 3.0) (P < 0.05). In conclusion, self-reported previous knee injury and low scores in three KOOS subscales significantly increase the risk of future time-loss knee injury in adolescent female football.

Back injuries in a cohort of schoolchildren aged 6-12: A 2.5-year prospective study

The aims of this prospective school cohort study were to describe the epidemiology of diagnosed back pain in childhood, classified as either nontraumatic or traumatic back injury, and to estimate the association with physical activity in different settings. Over 2.5 years, 1240 children aged 6-12 years were surveyed weekly using mobile text messages to ask about the presence or absence of back pain. Pain was clinically diagnosed and injuries were classified using the International Classification of Diseases version 10. Physical activity data were obtained from text messages and accelerometers. Of the 315 back injuries diagnosed, 186 injuries were nontraumatic and 129 were traumatic. The incidence rate ratio was 1.5 for a nontraumatic back injury compared with a traumatic injury. The overall estimated back injury incidence rate was 0.20 per 1000 physical activity units (95% confidence interval 0.18-0.23). The back injury incidence rates were higher for sports when exposure per 1000 physical activity units was taken into consideration and especially children horse-riding had a 40 times higher risk of sustaining a traumatic back injury compared to the risk during non-organized leisure time physical activity. However, the reasonably low injury incidence rates support the recommendations of children continuously being physically active.

Aerobic fitness testing in 6- to 9-year-old children: reliability and validity of a modified Yo-Yo IR1 test and the Andersen test

This study analysed the reliability and validity of two intermittent running tests (the Yo-Yo IR1 test and the Andersen test) as tools for estimating VO(2max) in children under the age of 10. Two groups, aged 6-7 years (grade 0, n = 18) and 8-9 years (grade 2, n = 16), carried out two repetitions of a modified Yo-Yo IR1 test (2 × 16 m) and the Andersen test, as well as an incremental treadmill test, to directly determine the VO(2max). No significant differences were observed in test-retest performance of the Yo-Yo IR1 test [693 ± 418 (±SD) and 670 ± 328 m, r (2) = 0.79, CV = 19%, p > 0.05, n = 32) and the Andersen test (988 ± 77 and 989 ± 87 m, r (2) = 0.86, CV = 3%, p > 0.05, n = 31). The Yo-Yo IR1 (r (2) = 0.47, n = 31, p < 0.002) and Andersen test performance (r (2) = 0.53, n = 32, p < 0.001) correlated with the VO(2max). Yo-Yo IR1 performance correlated with Andersen test performance (r (2) = 0.74, n = 32, p < 0.0001). In conclusion, the Yo-Yo IR1 and the Andersen tests are reproducible and can be used as an indicator of aerobic fitness for 6- to 9-year-old children.

High-level physical activity in childhood seems to protect against low back pain in early adolescence

BACKGROUND

The evidence on the impact of physical activity on back pain in children and adolescents has been contradicting. It has also been shown that the physical activity cannot accurately be estimated in children using questionnaires.

PURPOSE

The aim of this study was to establish if physical activity in childhood had any impact on back pain reporting in early adolescence (3 years later), using an objective instrumental measurement of physical activity.

STUDY DESIGN

Prospective cohort study.

PATIENT SAMPLE

Representative random sample of Danish children from the city of Odense sampled at age 9 years and followed-up at age 12 years.

OUTCOME MEASURES

The 1-month period prevalence of back pain (neck pain, mid back pain, and low back pain) was established using a structured interview.

METHODS

Physical activity was assessed with the MTI-accelerometer. The accelerometer provides a minute-by-minute measure of the physical activity performed. An overall measure of physical activity and time spent in high activity were studied in relation to back pain using logistic regression. The analyses were performed on the total sample and then stratified on back pain (yes/no) at baseline.

RESULTS

High physical activity (HPA) levels seem to protect against future low back pain and appear to actually "treat" and reduce the odds of future mid back pain. When comparing the least active children to the most active children, the least active had a multivariate odds ratio of 3.3 of getting low back pain and 2.7 of getting mid back pain 3 years later. When stratified on back pain at baseline, this effect on mid back pain was especially noticeable in children who had had mid back pain already at baseline, with an odds ratio of 7.2.

CONCLUSIONS

HPA in childhood seems to protect against low back pain and mid back pain in early adolescence. Larger prospective studies with repetitive follow-ups and preferably intervention studies should be performed, to see if these findings can be reproduced.

No evidence for presence of bacteria in modic type I changes

BACKGROUND

Recent studies suggest an association between sciatica and Propionibacterium acnes. "Modic type I changes" in the vertebrae are closely associated with sciatica and lower back pain, and recent studies have questioned the ability of conventional magnetic resonance imaging (MRI) to differentiate between degenerative Modic type I changes and vertebral abnormalities caused by infection.

PURPOSE

To test whether bacteria could be cultured from biopsies of Modic type I changes.

MATERIAL AND METHODS

Twenty-four consecutive patients with Modic type I changes in lumbar vertebrae had a biopsy taken from the affected vertebra by a strict aseptic procedure. The biopsy was split into two specimens, which were inoculated into thioglycolate agar tubes in the surgical theatre and transported to the microbiology laboratory. In the laboratory, one specimen was streaked onto plates and analyzed for anaerobic and aerobic culture. The other tube was left unopened and incubated directly. Plates and tubes were incubated for 2 weeks and observed for visible growth.

RESULTS

None of the biopsies yielded growth of anaerobic bacteria. In one patient, both biopsies yielded growth of Staphylococcus epidermidis, and in another patient coagulase-negative staphylococci were isolated from one biopsy. Both patients received oral antibiotics without convincing effect on symptoms.

CONCLUSION

Our results showed no evidence of bacteria in vertebrae with Modic type I changes. The isolation of staphylococci from two patients probably represented contamination.

Comparison of equations for predicting energy expenditure from accelerometer counts in children

Several prediction equations developed to convert body movement measured by accelerometry into energy expenditure have been published. The aim of this study was to examine the degree of agreement between three different prediction equations, when applied to data on physical activity in a large sample of children. We examined 1321 children (663 boys, 658 girls; mean age 9.6+/-0.4 years) from four different countries. Physical activity was measured by the MTI accelerometer. One equation, derived from doubly labeled water (DLW) measurements, was compared with one treadmill-based (TM) and one room calorimeter-based (CAL) equation (mixture of activities). Predicted physical activity energy expenditure (PAEE) was the main outcome variable. In comparison with DLW-predicted PAEE, both laboratory-derived equations significantly (P<0.001) overestimated PAEE by 17% and 83%, respectively, when based on a 24-h prediction, while the TM equation significantly (P<0.001) underestimated PAEE by 46%, when based on awake time only. In contrast, the CAL equation agreed better with the DLW equation under the awake time assumption. Predicted PAEE differ substantially between equations, depending on time-frame assumptions, and interpretations of average levels of PAEE in children from available equations should be made with caution. Further development of equations applicable to free-living scenarios is needed.

Tracking of objectively measured physical activity from childhood to adolescence: the European youth heart study

A number of studies have investigated tracking of physical activity from childhood to adolescence and, in general, these studies have been based on methods with some degree of subjectivity (e.g., questionnaires). The aim of the present study was to evaluate tracking of physical activity from childhood to adolescence using accelerometry, taking into account major sources of variation in physical activity. Both a crude and an adjusted model was fitted, and, in the adjusted model, analyses were corrected for seasonal variation, within-week variation, activity registration during night time sleep, within instrumental measurement error, and day-to-day variation in physical activity. In all, 208 subjects were included in the crude analyses. Stability coefficients estimated from the crude model were low (i.e., 0.18 and 0.19 for boys and girls, respectively) and only borderline significant. However, in the adjusted model highly significant stability coefficients of 0.53 and 0.48 for boys and girls, respectively, were observed. It was concluded that physical activity behavior tends to track moderately from childhood to adolescence.

Sources of variation in habitual physical activity of children and adolescents: the European youth heart study

The present study examined the influence of gender, maturity state, seasonality, type of measurement day and socioeconomic status (SES) on habitual physical activity in 8-10-year-old children and 14-16-year-old adolescents (n=1318). Physical activity was assessed objectively by accelerometry. The results showed a significant effect of the type of measurement day on physical activity with a general pattern of lower activity levels in weekends compared with weekdays. Furthermore, higher physical activity levels were observed during the months of spring/summer compared with the months of autumn/winter for the 8-10-year-olds, whereas no significant effect of months was observed for the 14-16-year-olds, possibly due to exam preparations and lack of physical activity registration during the months of summer for this cohort. SES was unrelated to physical activity in the 8-10-year-olds, whereas an inverse association was observed in the 14-16-year-olds. However, a post hoc analysis provided strong evidence that this latter result was biased by the accelerometers inability to pick up bicycling activities. Finally, boys were more physically active compared with girls, and maturity state was unrelated to physical activity. The results could prove useful for working out strategies to prevent inactivity and for adjusting for temporal sources of variation in physical activity in future studies.

Is active participation in specific sport activities linked with back pain?

A cross-sectional survey of 439 children/adolescents aged 12-13, living in Odense, Denmark, in the year 2001. To investigate (1) if there is any difference in back pain reporting among those practising specific sports as compared with non-performers and (2) if there is an association between specific kinds of sports and self-reported back problems. Back pain is a common complaint in young people and physical inactivity is generally thought to contribute to this. However, some specific sport activities may be detrimental or beneficial to the spine. Information was collected through a semi-structured interview, a physical examination, and a questionnaire. Associations for back pain, low back pain, mid back pain and neck pain in the preceding month were investigated in relation to specific sports. Associations were controlled for body mass index, puberty stage and sex. There was no association between back problems and the practising of sports in general. However, some sports were either positively or negatively associated with back pain. Taking into account the relatively small subgroups and multiple testing, some sports seem to be potentially harmful or beneficial. These sports should be investigated in proper longitudinal study designs, in relation to their effects on back problems in the young.

Secular trends in cardiorespiratory fitness and body mass index in Danish children: The European Youth Heart Study

AIM

To examine the secular trends in cardiorespiratory fitness (CF) and body fatness in Danish children. Trends were analyzed overall and across socioeconomic status (SES).

METHODS

Two cross-sectional studies conducted on 589 and 458 third-grade Danish children in 1997-1998 and 2003-2004, respectively. CF was determined by a maximal cycle-ergometer test. The lowest sex-specific quartile of CF in the study from 1997 to 1998 was used as a cut-point for low CF. Body mass index (BMI) cut-points were used to describe overweight, and SES was divided into two groups according to parents' occupation.

RESULTS

This study showed a secular decline in CF in girls overall. Increased CF, BMI, and prevalence of overweight were observed in boys with high SES, in boys with low SES, and in girls with low SES, respectively. However, after additional Bonferroni's correction, none of the statistical analyses performed across socioeconomic gradients reached significant P-values.

CONCLUSION

CF declined in girls overall. Although not statistically significant after additional Bonferroni's correction, results in general showed less favorable trends in low SES children. Thus, trying to describe secular trends in CF and body fatness overall without any regard to SES might disguise social-caused differences. However, further studies are needed in order to verify this hypothesis.

Infant feeding and components of the metabolic syndrome: findings from the European Youth Heart Study

AIMS

To assess the associations of type and duration of infant feeding with components of the metabolic syndrome in children aged 9 and 15.

METHODS

A total of 2192 randomly selected schoolchildren aged 9 and 15 years from Estonia (n = 1174) and Denmark (n = 1018) were studied. Insulin resistance (homoeostasis model assessment), triglyceride levels, high density lipoprotein cholesterol, and systolic blood pressure were measured.

RESULTS

Children who had ever been exclusively breast fed had lower systolic blood pressures than those who were not. With full adjustment for age, sex, country, birth weight, pubertal stage, body mass index, height, maternal and paternal education, income, smoking, and body mass index the mean systolic blood pressure of children who had ever been breast fed was 1.7 mm Hg (95% CI -3.0 to -0.5) lower than those who had never been exclusively breast fed. There was a dose-response in this association with decreasing mean systolic blood pressure across categories from never exclusively breast fed to breast fed for more than six months. Exclusive breast feeding was not associated with other components of the metabolic syndrome. Results were similar when examined separately in each country.

CONCLUSIONS

The magnitude of the association, its independence of important confounding factors, and the dose-response suggest that exclusive breast feeding is causally associated with reduced systolic blood pressure. The magnitude of the effect we found with blood pressure is comparable to the published effects of salt restriction and physical activity on blood pressure in adult populations, suggesting that it is of public health importance.

Secular trends in physical fitness and obesity in Danish 9-year-old girls and boys: Odense School Child Study and Danish substudy of the European Youth Heart Study

INTRODUCTION

Low physical fitness and obesity have been shown to be associated with cardiovascular disease (CVD) risk. Obesity is on the increase in many countries, but little is known about physical fitness trends. Monitoring of changes in fitness and obesity in the population is important for preventive strategies, and the aim of this study was to analyse the secular trends in fitness and body composition in Danish children.

MATERIALS AND METHODS

Two representative population studies were conducted 12 years apart on 9-year-old children in the same location: the Odense School Child Study in 1985-86 and the European Youth Heart Study in 1997-98. In both studies, physical fitness was determined by a maximal cycle ergometer test, and obesity was assessed by skinfolds.

RESULTS

Boys had a lower physical fitness and were fatter in 1997-98 than in 1985-86. In addition, an increased polarization is emerging, with the difference between the fit and the unfit and the difference between the lean and the fat being greater in 1997-98 than in 1985-86. In girls, a similar polarization was found, but no overall change in fitness or obesity.

CONCLUSION

The negative trend and increased polarization for physical fitness and obesity in Danish children suggest a future generation with a higher degree of CVD risk.

Objectively measured physical activity correlates with indices of insulin resistance in Danish children

OBJECTIVE

To explore the association between measures of insulin resistance with objectively assessed physical activity.

DESIGN

School-based, cross-sectional study.

SUBJECTS

A randomly selected sample of 589 children (310 girls, 279 boys, mean (standard deviations, s.d.) age=9.7 (0.44) y, weight=33.6 (6.4) kg, height=1.39 (0.06) m) from Denmark.

METHODS

Fasting blood samples were analysed for serum insulin and glucose. Physical activity was measured with the uniaxial Computer Science and Applications (CSA) model 7164 accelerometer, worn for at least 3 days (>/=10 h day(-1)). Adiposity was assessed by the sum of four skinfolds. Multiple linear regression were performed to model insulin and glucose from average CSA output, adjusted for age, gender, puberty, ethnicity, birth weight, parental smoking, socioeconomic group, and CSA unit. In addition, we adjusted for skinfold thickness.

RESULTS

Mean fasting serum glucose ranged from 4.1 to 6.5 mmol l(-1) with a mean (s.d.) of 5.1 (0.37) mmol l(-1). Fasting insulin was negatively correlated with CSA output on levels of adjustment. Fasting glucose was not significantly associated with physical activity. However, in girls both indices of insulin resistance were significantly related to activity, whereas in boys none of the associations were significant.

CONCLUSION

Physical activity is inversely associated with fasting insulin in the nondiabetic range of fasting glucose. The relationship was stronger for insulin than for glucose, indicating compensatory action by the beta cells. Our data emphasise the importance of physical activity in children for the maintenance of metabolic control.

Comparison of two intervention programmes in young female players in European handball - with and without ankle disc

INTRODUCTION

The prevention of injuries in all sports calls for a structured plan. The plan consists, as earlier described, of four steps. We have previously presented studies incorporating all four steps. The studies have shown that it is possible to prevent most injuries in young female players in European handball by applying a training programme combining the use of an ankle disc with functional strength training. In the previous studies we were not able to discriminate whether the preventive effect was due to the functional strength training or the training with the ankle disc. The aim of this study was to compare a programme with ankle disc and functional strength training with a programme with functional strength training only.

METHODS

Twenty handball teams were asked to participate, and 16 of 20 handball teams agreed to participate. The teams were cluster randomised to either the programme with or without an ankle disc.

RESULTS

The group using the programme without the ankle disc had a significantly higher number of traumatic injuries (16 vs. 6). The incidences of traumatic injuries in the ankle disc group were 2.4 (95% CI 0.7; 6.2) injuries per 1000 h of match and 0.2 (95% CI 0.02; 0.7) injuries per 1000 h of practice. In the group without ankle disc the incidences were 6.9 (95% CI 3.3; 12.7) injuries per 1000 h of match and 0.6 (95% CI 0.2; 1.3) injuries per 1000 h of practice. A significantly higher multivariate odds ratio (4.8) was found in the group not using the ankle disc. In addition the group using the ankle disc had significantly fewer moderate and major injuries.

CONCLUSION

By adding ankle disc training to a training programme with functional strength training, it is possible to reduce the number of injuries significantly, especially the number of moderate and major injuries.

Biological cardiovascular risk factors cluster in Danish children and adolescents: the European Youth Heart Study

BACKGROUND

The aim of this study was to determine whether the number of participants with multiple coronary heart disease (CHD) risk factors exceeded the number expected from a random distribution.

METHODS

A cross-sectional study of 1020 randomly selected boys and girls, 9 and 15 years old, was conducted. Risk factors were total cholesterol, HDL-cholesterol, triglyceride, serum insulin, and blood pressure. Physical fitness was assessed from a maximal cycle test and body fat from the sum of four skinfolds. Risk factors selected in the analysis were those related to the metabolic syndrome.

RESULTS

More participants than expected had four or five CHD risk factors. Four risk factors were found in 3.03 (95% confidence interval (CI): 2.24-4.10) times as many participants as expected from a random distribution and five risk factors were found in 8.70 (95% CI: 4.35-17.4) times as many participants as expected. Fifty (5.4%) had four or five risk factors and in these individuals physical fitness was 1.2 standard deviation (SD) lower and body mass index (BMI) 1.6 SD higher than mean values for the population.

CONCLUSION

Clustering of risk factors for the metabolic syndrome was found in children and adolescents. Low levels of physical fitness and raised BMI in these individuals indicate that lifestyle factors such as physical activity and diet may influence the development of these unhealthy risk profiles.

Back pain reporting pattern in a Danish population-based sample of children and adolescents

STUDY DESIGN

A cross-sectional survey of 806 pupils in Odense, Denmark was performed. This survey included children and adolescents ages 8 to 10 and 14 to 16 years obtained through two-stage cluster sampling from schools stratified according to school type, location, and socioeconomic character of the uptake area.

OBJECTIVES

To establish the 1-month prevalence of neck, middle back, and low back pain and the consequences this disorder may have in relation to age and gender.

SUMMARY OF BACKGROUND DATA

The differences in definitions of back pain and the variety of age groups included in previous studies make it difficult to draw clear conclusions about the onset of pain for various spinal regions in the young.

METHODS

Information on back pain within the preceding month, obtained through a standardized interview of 481 children and 325 adolescents, was categorized according to area of pain, age, and gender. The consequences of back pain also were studied.

RESULTS

The 1-month prevalence of back pain was 39%. Thoracic pain is most common in childhood, whereas thoracic pain and lumbar pain are equally common in adolescence. Neck pain and pain in more than one area of the spine are rare in both age groups. No gender differences were found. Of those who had back pain, 38% also reported some type of consequence, usually either visits to a medical physician or diminished physical activities.

CONCLUSIONS

For clinical and research purposes, neck pain, middle back pain, and low back pain in childhood should be regarded as three specific entities. In future research the data for different age groups should be reported separately.

[Obesity among children--with particular reference to Danish circumstances]

Obesity is one of the most important predictors and causes of such lifestyle diseases as metabolic syndrome, type 2 diabetes, and cardiovascular disease. It is thus imperative to follow the trend longitudinally in the population. Measurement of obesity in children and adolescents is difficult; many studies use the body mass index as a measure, regardless of the fact that it is inappropriate. Skinfolds or the ponderal index should be used, instead. Recent Danish studies suggest that the incidence of childhood and adolescent obesity is increasing and that those who are overweight are even more so today than earlier. Obesity is caused by a number of factors, genetic, social, environmental, and lifestyle, all of which play an important role. One of the main causes of the increase in childhood obesity in Denmark today is the lower level of physical activity than formerly. The prospects for the future are an increase in obesity and incidence of lifestyle diseases with a poorer quality of life and a shorter life time expectancy.

Physical activity assessed by activity monitor and doubly labeled water in children

PURPOSE

To validate the Computer Science and Application's (CSA) activity monitor for assessment of the total amount of physical activity during two school-weeks in 9-yr-old children and to develop equations to predict total energy expenditure (TEE) and activity energy expenditure (AEE) from activity counts and anthropometric variables.

METHODS

A total of 26 children (15 boys and 11 girls, mean age 9.1 +/- 0.3 yr) were monitored for 14 consecutive days. TEE was simultaneously measured by the doubly labeled water method. Averaged activity counts (counts.min(-1)) were compared with data on: 1) TEE, 2) AEE = TEE minus basal metabolic rate (BMR; estimated from predictive equations), and 3) daily physical activity level (PAL = TEE/BMR).

RESULTS

Physical activity determined by activity counts was significantly related to the data on energy expenditures: TEE (r = 0.39; P < 0.05), AEE (r = 0.54; P < 0.01), and PAL (r = 0.58; P < 0.01). Multiple stepwise regression analysis showed that TEE was significantly influenced by gender, body composition (body weight or fat free mass), and activity counts (R(2) = 0.54--0.60). AEE was significantly influenced by activity counts and gender (R(2) = 0.45). There were no significant differences between activity counts and PAL in discriminating among activity levels with "low" (PAL < 1.56), "moderate" (1.57 < or = PAL > or = 1.81), and "high" (PAL > 1.81) intensity.

CONCLUSION

Activity counts from the CSA activity monitor seems to be a useful measure of the total amount of physical activity in 9-yr-old children. Activity counts contributed significantly to the explained variation in TEE and was the best predictor of AEE.

Prevention of injuries in young female players in European team handball. A prospective intervention study

Young female players in European handball have a very high injury incidence, up to 50 injuries per 1000 hours of game. More than half of these injuries happen without any external cause. The aim of the study was to investigate the effect of an intervention programme designed to reduce the number of injuries in young female players in European handball, with special emphasis on injuries in the lower extremities. The programme was created using elite athlete training programmes and those designed for rehabilitation of injured athletes with functional instability of their ankles and rupture of the anterior cruciate ligament. It included the use of an ankle disk for 10-15 min at all practice sessions, for one 10-month season (August 1995-May 1996). Twenty-two teams participated in the study, and were randomly assigned to the intervention or control group. Eleven teams with 111 players were randomised to the intervention group and 11 teams with 126 players to the control group. Data were analysed using a t-test for continuous variables, chi2-analysis and Fisher's exact test for dichotomous variables and multivariate methods to determine odds-ratios. The results indicated that using the intervention programme decreased the numbers of both traumatic and overuse injuries significantly. The differences in injuries between the groups were 80% during games and 71% during practice. In addition, the players in the control group had a 5.9 times higher risk of acquiring an injury than the players in the intervention group.

Injuries in young female players in European team handball

The purpose of this study was to examine the nature, extent and severity of sports injuries in young female players in European team handball and to identify the etiological factors involved in the injuries. Twenty-two teams with 217 players, aged 16-18 years, participated in the study. A very high injury incidence during games was observed, with 40.7 injuries/1000 hours of game. Backplayers had the highest incidence (54.8/1000 hours), which is five times higher than any previously recorded injury incidence in players in European team handball. We found that 92.9% of injuries were traumatic and 7.1% were from overuse. One-hundred and twenty-four of the 211 injuries were traumatic injuries of the lower extremities. Of these 63 (51%) were without contact with an opponent. The study confirmed that European team handball is a sport that has a very high injury rate, especially regarding young female players. Field position and earlier injuries are major risk factors, with an earlier injury being the single highest risk factor and with backplayers having a significantly higher number of injuries than players in other field positions.

Aseptic loosening of BonelocR cemented hip prostheses

We present a systematic clinical and radiographic study of 147 patients who had total hip replacements from February 1992 to May 1993. BonelocR cement was used in 108, and PalacosR cement with gentamicin in 39 patients who had an increased risk of infection. At follow-up after 24 to 39 months, 26 cases with BonelocR cement had failed; there were no clinical failures in the PalacosR group.

[Marginal costs of total hip replacement--experiences from a county hospital department]

The marginal cost of total hip replacement was analysed at a county hospital in Denmark. We found that, with correction for inflation the price of a hip prosthesis has remained stable. In addition, we found that the cost of total hip replacement at a public hospital is considerably lower than the price listed at private hospitals in Denmark. We therefore conclude, that from an economic viewpoint it would be better to expand the existing capacity at public hospitals than that the public health service should pay for treatment of patients at private hospitals.

[Cemented hip alloplasty. 11-13-year follow-up study of the Richards' series 2 hip prostheses]

The study comprises a follow-up (11-13 years) of an orthopaedic department's first 131 consecutive cemented total hip arthroplasties (THA). All operations were performed with Richards' Series 2. Posterior approach, plug, lavage, cementation with cement pistol, antibiotics and low-dose heparin. At the time of follow-up 44 patients (38%) were dead (= 49 THA), and 56 patients representing 65 THA (50%) were available for the follow-up, on average 11.95 years (11-13 years) after the operation. The patients hip/hips were examined as regards a) pain b) walking ability and c) hip-mobility (M. d'Aubigné) (HFI). A frontal x-ray of the pelvis and hip/hips was taken. The examining surgeon evaluated the hip/hips based on a clinical examination and the x-ray as 1 = stable, 2 = perhaps loose, 3 = most likely loose and 4 = definitely loose both with regard to the acetabular and femoral component. Pre-operatively 78% of the patients had an ideopathic coxarthrosis. Eight patients had considerable postoperative complications. Ten patients (7.8%) were reoperated during the examination period: two due to loosening of the total prosthesis, one due to loosening of the cup, three due to loosenings of the femoral component, two because of recurring luxations, one late (deep) infection and one fracture of the femur near the prosthesis. Preoperatively the patients' HFI was at 8.6, at follow-up 15.8. The clinical and the radiographic examination showed that 86% of the acetabular cups and 63% of the femoral components were fixed solidly.(ABSTRACT TRUNCATED AT 250 WORDS)

[A closed emergency unit. Consequences for referral patterns and economics]

During the mid 1980's the emergency-room at Faaborg Hospital changed status from being open to semi-closed. From then on the patients had to contact a general practitioner before going to the emergency-room. The general practices in the area were then supposed to have a referring function. We decided to evaluate the consequences of this decision in 1991. From 25 August to 1 December 1991 we registered all patients who contacted the emergency-room. The conclusions were that no changes in the types of patients had occurred, and that it was at a greater cost to the National Health Service.