The effect of an integrated perceived competence and motor intervention in children with developmental coordination disorder.

BACKGROUND AND AIMS: Children with DCD have lower self-perceptions and are less physically active than typically developing children. The aim of this quasi-experimental study was to investigate whether an integrated perceived competence and motor intervention affects DCD children's motor performance, self-perceptions, and physical activity compared with a motor intervention only. METHODS AND PROCEDURES: The intervention group consisted of 20 children and the care-as-usual group consisted of 11 children, all aged 7-10 years. The perceived competence component of the intervention focused primarily on providing positive, specific, and progress feedback to enhance self-perceptions. We assessed children at baseline, after 12 treatment sessions (trial end-point), and at 3-month follow-up. OUTCOMES AND RESULTS: Mixed linear models revealed no differences between the intervention and the care-as-usual group on any of the outcome measures. Children improved their motor performance and increased their perceived athletic competence, global self-esteem, and perceived motor competence after 12 treatment sessions. This improvement was maintained at 3-month follow-up. Motor task values and physical activity remained unchanged for all children. CONCLUSIONS AND IMPLICATIONS: A perceived competence and motor intervention is as effective as care-as-usual in children with DCD. Future research should focus on improving physical activity in children with DCD. WHAT THIS PAPER ADDS: This is the first study that has investigated the effect of an integrated perceived competence and motor intervention (intervention group) on motor performance, self-perceptions, and physical activity compared with a motor intervention (care-as-usual group) in children with DCD. We made the perceived competence component explicit by providing positive, specific, and progress feedback to enhance children's self-perceptions. Also, this is one of the first studies that has investigated the effect after both 12 treatment sessions (trial end-point) and after 3 months of no intervention (3-month follow-up). We found no differences between the intervention and the care-as-usual group, but children improved their motor performance and increased (most) of their self-perceptions after 12 treatment sessions, while physical activity remained the same. The improvement was still present at the 3-month follow-up. We also benchmarked our results about self-perceptions and physical activity to a group of typically developing children. Self-perceptions in children with DCD had improved to the level of typically developing children after 12 treatment sessions, but their physical activity levels remained significantly lower. This result was the same at the 3-month follow-up, except for perceived athletic competence, which was lower in children with DCD at the 3-month follow-up. In accordance with previous intervention studies that have investigated children with DCD, we found large intra-group variability in the change in motor performance and self-perceptions in children with DCD. We argue that we need to better understand why some children with DCD improve and others do not after a motor intervention.

The change in perceived motor competence and motor task values during elementary school: A longitudinal cohort study.

Participation in motor activities is essential for social interaction and life satisfaction in children. Self-perceptions and task values have a central position in why children do or do not participate in (motor) activities. Investigating developmental changes in motor self-perceptions and motor task values in elementary school children would provide vital information about their participation in motor activities. We therefore examined the change in, and associations between, self-perceptions and task values of fine motor competence, ball competence, and athletic competence in 292 children from kindergarten to grade 4. We also investigated differences between boys and girls, and between children with motor problems and typically developing children. Results indicated that self-perceptions and task values are domain specific and differ between boys and girls, but not between children with motor problems and typically developing children. Self-perceptions were not associated with task values. Educators should address specific self-perceptions to enhance participation into the corresponding motor activities in children between kindergarten and grade 4, and differences in self-perceptions and task values between boys and girls should be taken into account.

Estimating peak oxygen uptake in adolescents with cystic fibrosis.

OBJECTIVES: To predict peak oxygen uptake (VO2 peak) from the peak work rate (W peak) obtained during a cycle ergometry test using the Godfrey protocol in adolescents with cystic fibrosis (CF), and assess the accuracy of the model for prognostication clustering. METHODS: Out of our database of anthropometric, spirometric and maximal exercise data from adolescents with CF (N=363; 140 girls and 223 boys; age 14.77 ± 1.73 years; mean expiratory volume in 1 s (FEV1%pred) 86.82 ± 17.77%), a regression equation was developed to predict VO2 peak (mL/min). Afterwards, this prediction model was validated with cardiopulmonary exercise data from another 60 adolescents with CF (28 girls, 32 boys; mean age 14.6 ± 1.67 years; mean FEV1%pred 85.43 ± 20.01%). RESULTS: We developed a regression model VO2 peak (mL/min)=216.3-138.7 × sex (0=male; 1=female)+11.5 × W peak; R(2)=0.91; SE of the estimate (SEE) 172.57. A statistically significant difference (107 mL/min; p<0.001) was found between predicted VO2 peak and measured VO2 peak in the validation group. However, this difference was not clinically relevant because the difference was within the SEE of the model. Furthermore, we found high positive predictive and negative predictive values for the model for prognostication clustering (PPV 50-87% vs NPV 82-94%). CONCLUSIONS: In the absence of direct VO2 peak assessment it is possible to estimate VO2 peak in adolescents with CF using only a cycle ergometer. Furthermore, the regression model showed to be able to discriminate patients in different prognosis clusters based on exercise capacity.

The Steep Ramp Test in Dutch white children and adolescents: age- and sex-related normative values.

BACKGROUND: The Steep Ramp Test (SRT), a feasible, reliable, and valid exercise test on a cycle ergometer, may be more appealing for use in children in daily clinical practice than the traditional cardiopulmonary exercise test because of its short duration, its resemblance to children's daily activity patterns, and the fact that it does not require respiratory gas analysis. OBJECTIVE: The aim of the present study was to provide sex- and age-related normative values for SRT performance in Dutch white children and adolescents who were healthy and 8 to 19 years old. DESIGN: This was a cross-sectional, observational study. METHODS: A total of 252 Dutch white children and adolescents, 118 boys (mean age=13.4 years, SD=3.0) and 134 girls (mean age=13.4 years, SD=2.9), performed the SRT (work rate increment of 10, 15, or 20 W·10 s(-1), depending on body height) to voluntary exhaustion to assess peak work rate (WRpeak). Normative values are presented as reference centiles developed by use of generalized additive models for location, scale, and shape. RESULTS: Peak work rate correlated highly with age (r=.915 and r=.811), body mass (r=.870 and r=.850), body height (r=.922 and r=.896), body surface area (r=.906 and r=.885), and fat free mass (r=.930 and r=.902) in boys and girls, respectively. The reference curves demonstrated an almost linear increase in WRpeak with age in boys, even when WRpeak was normalized for body mass. In contrast, absolute WRpeak in girls increased constantly until the age of approximately 13 years, when it started to level off. Peak work rate normalized for body mass in girls showed only a slight increase with age until 14 years of age, when a slight decrease in relative WRpeak was observed. LIMITATIONS: The sample may not have been entirely representative of the Dutch population. CONCLUSIONS: The present study provides sex- and age-related normative values for SRT performance in terms of both absolute WRpeak and relative WRpeak, thereby facilitating the interpretation of SRT results by clinicians and researchers.

Prediction of gross motor development and independent walking in infants born very preterm using the Test of Infant Motor Performance and the Alberta Infant Motor Scale.

BACKGROUND: One objective of a neonatal follow-up program is to examine and predict gross motor outcome of infants born preterm. AIMS: To assess the concurrent validity of the Test of Infant Motor Performance (TIMP) and the Alberta Infant Motor Scale (AIMS), the ability to predict gross motor outcome around 15 months corrected age (CA), and to explore factors associated with the age of independent walking. METHODS: 95 infants, born at a gestational age <30 weeks, were assessed around 3, 6 and 15 months CA. At 3 months CA, correlations of raw-scores, Z-scores, and diagnostic agreement between TIMP and AIMS were determined. AIMS-score at 15 months CA and parental-reported walking age were outcome measures for regression analyses. RESULTS: The correlation between TIMP and AIMS raw-scores was 0.82, and between Z-scores 0.71. A cut-off Z-score of -1.0 on the TIMP had 92% diagnostic agreement (κ = 0.67) with an AIMS-score < P10. Neither TIMP- nor AIMS-scores at 3 months CA were associated with the gross motor outcome at 15 months CA. The AIMS-scores at 6 months CA predicted the AIMS-scores at 15 months CA with an explained variance of 19%. Median walking age was 15.7 months CA, with which only the hazard ratio of the AIMS at 6 months CA and ethnicity were significantly associated. CONCLUSIONS: Prediction of gross motor development at 15 months CA and independent walking was not possible prior to 6 months CA using the AIMS, with restricted predictive value. Cultural and infant factors seem to influence the onset of independent walking.

Clinical course of asymmetric motor performance and deformational plagiocephaly in very preterm infants.

OBJECTIVES: To describe the clinical courses of positional preference and deformational plagiocephaly up to 6 months corrected age (CA) in infants born at gestational age <30 weeks or birth weight <1000 g, and to explore predictive factors for the persistence of these phenomena. STUDY DESIGN: A total of 120 infants were examined 3 times each. The presence of deformational plagiocephaly and a score of 0-6 on an asymmetry performance scale served as outcome measures at 6 months CA. Predictive factors were determined using regression analysis. RESULTS: The prevalence of a positional preference of the head was 65.8% (79 of 120) at term-equivalent age (TEA) and 36.7% (44 of 120) at 3 months CA and that of deformational plagiocephaly was 30% (36 of 120) at TEA and 50% (60 of 120) at 3 months CA. At 6 months CA, 15.8% of the infants (19 of 120) scored ≥ 2 of a possible 6 on the asymmetry performance scale and 23.3% (28 of 120) had deformational plagiocephaly. Sleeping in the supine position was predictive of an asymmetric motor performance at 6 months CA. Chronic lung disease and/or slow gross motor maturation at 3 months CA predicted the persistence of deformational plagiocephaly. CONCLUSION: Infants born very preterm may develop deformational plagiocephaly. A positional preference of the head at TEA seems to be a normal aspect of these infants' motor repertoire, with limited ability to predict persistence of an asymmetric motor performance. The decreased prevalence of deformational plagiocephaly between 3 and 6 months CA indicates an optimistic course. Infants with a history of chronic lung disease and/or slow gross motor maturation merit timely intervention.

Measurement of clinically relevant functional health perceptions in patients with whiplash-associated disorders: the development of the whiplash specific activity and participation list (WAL).

PURPOSE: The International Classification of Human Functioning Disability and Health (ICF) provides insight into functional health status in patients with whiplash-associated disorders (WAD). In the assessment of functional limitations in patients with WAD, there are several condition-specific questionnaires available. Estimation of the true relationship between the separate constructs of the ICF is only possible if the items of the salient questionnaires measure exactly the constructs of interest, while not simultaneously measuring other constructs of the model. This study aimed to develop a condition specific and clinically relevant and usable instrument for patients with WAD that measures activity limitations and participation restrictions, as defined by the ICF framework. METHODS: Item generation consisted of (1) a semi-structured interview which was conducted among 69 WAD patients; (2) a Delphi study involving 13 health professionals experienced in the assessment of patients with WAD; (3) a literature search for items from self-assessment questionnaires for neck pain. RESULTS: A 35-item condition-specific self-assessment questionnaire for patients with WAD was developed. This new questionnaire measures purely activity limitations and participation restrictions according to the ICF and is based on patients' opinions and expert opinions. CONCLUSION: The whiplash activity and participation list tends to measure clinically relevant activity limitations and participation restrictions in WAD patients.

Content validity of the Dutch version of the Neck Bournemouth Questionnaire.

OBJECTIVE: Mechanical neck pain is a common human phenomenon. In most cases, no patho-anatomical lesion can be identified with the limitations of current radiological imaging. Therefore it is preferable to assess patients with neck pain with a focus on functioning and health, within a biopsychosocial model. The Neck Bournemouth Questionnaire aims to assess biopsychosocial aspects of neck pain. However, the content validity of the Neck Bournemouth Questionnaire Dutch language version (NBQ-NL) in relation to the International Classification of Functioning, Disability and Health (ICF) is unknown. The purpose of the study was to examine the content validity of the NBQ-NL in relation to the health components of the ICF. METHOD: Content validity was assessed in relation to the ICF, by means of Discriminant Content Validity (DCV). RESULTS: The results indicate that the NBQ-NL measures four components of the five ICF (impairment, activity, participation and personal factors). CONCLUSION: The NBQ is a multidimensional questionnaire, representing four of the five components of the ICF.

The steep ramp test in healthy children and adolescents: reliability and validity.

PURPOSE: This study aimed to examine the reliability and validity of the steep ramp test (SRT), a feasible, maximal exercise test on a cycle ergometer that does not require the use of respiratory gas analysis, in healthy children and adolescents. METHODS: Seventy-five children were randomly divided in a reliability group (n = 37, 17 boys and 20 girls; mean ± SD age = 13.86 ± 3.22 yr), which performed two SRTs within 2 wk, and a validity group (n = 38, 17 boys and 21 girls; mean ± SD age = 13.85 ± 3.20 yr), which performed both an SRT and a regular cardiopulmonary exercise test (CPET) with respiratory gas analysis within 2 wk. Peak work rate (WRpeak) was the main outcome of the SRT. Peak oxygen uptake (VO2peak) was the main outcome of the CPET. Reliability was examined with the intraclass correlation coefficient and a Bland and Altman plot, whereas validity was assessed using Pearson correlation coefficients and stepwise linear regression analysis. RESULTS: Reliability statistics for the WRpeak values attained at the two SRTs showed an intraclass correlation coefficient of 0.986 (P < 0.001). The average difference between the two SRTs was -6.4 W, with limits of agreement between +24.5 and -37.5 W. A high correlation between WRpeak attained at the SRT and the V˙O2peak achieved during the CPET was found (r = 0.958; P < 0.001). Stepwise linear regression analysis provided the following prediction equation: VO2peak (mL·min) = (8.262 WRpeak SRT) + 177.096 (R2 = 0.917, SEE = 237.4). CONCLUSION: The results suggest that the SRT is a reliable and valid exercise test in healthy children and adolescents, which can be used to predict VO2peak.

Active head lifting from supine in early infancy: an indicator for non-optimal cognitive outcome in late infancy.

AIM: To explore whether active head lifting from supine (AHLS) in early infancy is associated with cognitive outcome in the second year of life. METHOD: The presence of AHLS was always recorded in the notes of infants admitted to our tertiary neonatal intensive care unit. Random sampling was used to pair infants with AHLS with two comparison infants without AHLS whose sex, gestational age, birth year (1993-2009), time of assessment, and developmental test (Griffiths Mental Development Scales, Mental Scale of the Bayley Scales of Infant Development-II, or cognitive subtest of the Bayley Scales of Infant and Toddler Development-III) were comparable. Brain injury identified from neonatal cranial ultrasound scans was classified as no - mild or moderate - severe. Z-scores of cognitive test outcomes were calculated for multivariable analysis. RESULTS: Eighty-seven preterm (34 males, 53 females) and 40 term (17 males, 23 females) infants with AHLS were identified. AHLS was documented at a mean (corrected) age of 7.0 (SD 1.7) and 8.1 (SD 2.2) months respectively. The cognitive assessments were performed at a mean corrected age of 15.7 (SD 1.7) and 23.9 (SD 1.6) months in preterm infants, and 19.1 (SD 2.3) months in term infants. The mean cognitive outcome of preterm and term infants with AHLS was lower than that of infants without AHLS (p=0.002 and p=0.004 respectively). This remained after excluding infants with cerebral palsy with matching comparison infants (p=0.001 in preterm and p=0.001 in term infants). The mean difference was highest (1.35SD) between term male infants and comparison infants (p=0.001). INTERPRETATION: AHLS is associated with a less favourable cognitive outcome in the second year of life in preterm as well as in term-born infants than in comparison infants.

Prevalence and predictors of idiopathic asymmetry in infants born preterm.

BACKGROUND: An idiopathic asymmetry in posture of the head is recognized as a risk factor to develop a deformational plagiocephaly (DP). In our neonatal follow-up clinic, an IA is often observed in infants born preterm at term-equivalent age (TEA). AIMS: To explore (1) the prevalence of an idiopathic asymmetry in 192 infants (gestational age ≤32.0 weeks) at TEA and 6 months corrected age (CA), (2) whether demographical, perinatal, and medical factors were predictors of the asymmetry, and (3) differences in motor maturation between infants with and without asymmetry. METHODS: In a retrospective study, frequencies of idiopathic asymmetry and DP, putative predictors, and Alberta Infant Motor Scale scores at 6 months CA were abstracted and analyzed with Chi(2), Mann-Whitney, logistic regression and T-test. RESULTS: The prevalence rate of a positional preference of the head at TEA was 44.8% (n=86), 10.4% (20/192) had a DP at TEA and 13% (25/192) at 6 months CA. Positional preference, multiple birth and male gender predicted the presence of DP (p<.05, odds ratio 3.0, 3.2, and 3.1 respectively). Gross motor maturity at 6 months CA was less developed in infants with a positional preference at TEA compared to preterm norms (p=0.01). CONCLUSIONS: The high prevalence of a positional preference in infants born preterm at term equivalent age requires extra alertness to prevent the development of a deformational plagiocephaly, especially in boys and twins. Although, considering the lower prevalence of plagiocephaly at 6 months CA, therapists should be aware of over treating these infants.

Decreasing incidence and severity of cerebral palsy in prematurely born children.

OBJECTIVE: To examine incidence and severity of cerebral palsy (CP), and associated factors among preterm survivors (gestational age <34 weeks), admitted to a neonatal intensive care unit from 1990-2005. STUDY DESIGN: Eighteen antenatal, perinatal and postnatal factors were analyzed. The cohort was divided in four birth periods: 1990-1993 (n=661), 1994-1997 (n=726), 1998-2001 (n=723), and 2002-2005 (n=850). The Gross Motor Function Classification System was used as primary outcome measure (mean age: 32.9 ± 5.3 months). Logistic regression analyses were used. RESULTS: CP incidence decreased from 6.5% in period I, to 2.6%, 2.9% and 2.2% (P<.001) in period II-IV, respectively. Simultaneously, cystic periventricular leukomalacia (c-PVL) decreased from 3.3% in period I to 1.3% in period IV (P=.004). Within the total cohort (n=3287), c-PVL grade III decreased from 2.3% in period I to 0.2% in period IV (P=.003). The number of children with Gross Motor Function Classification System levels III-V decreased from period I to IV (P=.035). Independent risk factors for CP were c-PVL and severe intraventricular hemorrhage, whereas antenatal antibiotics, presence of an arterial line, Caesarean section, and gestational age were independent protective factors. CONCLUSION: CP incidence and severity decreased from 1990-1993 onward, which could be attributed to a reduction of 93% in severe c-PVL.

The Utrecht approach to exercise in chronic childhood conditions: the decade in review.

PURPOSE: To summarize and discuss current evidence and understanding of clinical pediatric exercise physiology focusing on the work the research group at Utrecht and others have performed in the last decade in a variety of chronic childhood conditions as a continuation of the legacy of Dr Bar-Or. KEY POINTS: The report discusses current research findings on the cardiopulmonary exercise performance of children (and adolescents) with juvenile idiopathic arthritis, osteogenesis imperfecta, achondroplasia, hemophilia, cerebral palsy, spina bifida, cystic fibrosis, and childhood cancer. Exercise recommendations and contraindications are provided for each condition. Implications for clinical practice and future research in this area are discussed for each of the chronic conditions presented. CLINICAL IMPLICATIONS: The authors provide a basic framework for developing an individual and/or disease-specific training program, introduce the physical activity pyramid, and recommend a core set of clinical measures to be used in clinical research.

Supramaximal verification of peak oxygen uptake in adolescents with cystic fibrosis.

PURPOSE: To study whether peak oxygen uptake ((Equation is included in full-text article VO2 peak), attained in traditional cardiopulmonary exercise testing (CPET) in adolescents with cystic fibrosis (CF), could be verified by a supramaximal exercise test. METHODS: Sixteen adolescents with CF (forced expiratory volume in 1 second as % of predicted [range, 45%-117%]) volunteered and successively performed CPET and a supramaximal test (Steep Ramp Test [SRT] protocol). RESULTS: Cardiopulmonary exercise testing and the SRT resulted in comparable cardiorespiratory peak values. We found no significant difference in oxygen uptake ((Equation is included in full-text article VO2 peak/kg) between CPET and the SRT (38.9 ± 7.4 and 38.8 ± 8.5 mL min kg, respectively; P = .81). We found no systemic bias for CPET and SRT measurements of (Equation is included in full-text article VO2 peak/kg and no differences between CPET and SRT (Equation is included in full-text article VO2 peak values within and between the maximal and non-maximal effort groups (P > .4). CONCLUSION: The (Equation is included in full-text article VO2 peak measured in CPET seems to reflect the true (Equation is included in full-text article.)O2 peak in adolescents with CF.

Reproducibility of maximal and submaximal exercise testing in "normal ambulatory" and "community ambulatory" children and adolescents with spina bifida: which is best for the evaluation and application of exercise training?

BACKGROUND: With emerging interest in exercise and lifestyle interventions for children and adolescents with spina bifida, there is a need for appropriate measurements in exercise testing. OBJECTIVE: The purpose of this study was to assess both reliability and agreement of maximal and submaximal exercise measures in "normal ambulatory" and "community ambulatory" children and adolescents with spina bifida. DESIGN: This was a reproducibility study. METHODS: Twenty-three children and adolescents with spina bifida (10 normal ambulatory and 13 community ambulatory) participated in the study. Maximal exercise outcomes were measured using a graded treadmill test. Peak measures (peak oxygen uptake [V(O2)peak], peak heart rate [HRpeak], heart rate response [HRR], and oxygen pulse) were recorded. For submaximal measures, heart rate (HR) and oxygen uptake (V(O2)) at the ventilatory threshold and oxygen uptake efficiency slope (OUES) were derived from the maximal measures. Functional performance was measured as the 6-minute walking distance and the maximal speed during the treadmill test. After checking for normality and heteroscedasticity, paired t tests, intraclass correlation coefficients (ICCs), and the smallest detectable difference (SDD) or the coefficient of variation (CV) were calculated. RESULTS: Performance measures showed good reliability and agreement. For maximal measures, acceptable ICCs were found for all measures. For submaximal measures, only HR at the ventilatory threshold showed an ICC of less than .80. Agreement showed a CV of less than 10% for all measures, except for V(O2) at the ventilatory threshold, HRR, and OUES. LIMITATIONS: Limitations of the study include missing data due to equipment failure. Furthermore, the outcomes were limited to normal ambulatory and community ambulatory children and adolescents with spina bifida. CONCLUSIONS: Both maximal and submaximal measures of exercise testing can be used for discriminative purposes in ambulatory children and adolescents with spina bifida. For evaluative purposes, HR measures are superior to V(O2) measures, while taking into account the individual variation of 5% to 8%. The SDD was 0.5 km/h for peak speed and 36.3 m for 6-minute walking distance. Heart rate response, oxygen pulse, and OUES are not recommended in the evaluation of exercise testing in this population.

Oxygen uptake efficiency slope in healthy children.

The objective of this study was to investigate the characteristics of the submaximal Oxygen Uptake Efficiency Slope (OUES) in a healthy pediatric population. Bicycle ergometry exercise tests with gas-analyses were performed in 46 healthy children aged 7-17 years. Maximal OUES, submaximal OUES, VO(2)peak, V(E)peak, and ventilatory threshold (VT) were determined. The submaximal OUES correlated highly with VO(2)peak, V(E)peak, and VT. Strong correlations were found with basic anthropometric variables. The submaximal OUES could provide an objective, independent measure of cardiorespiratory function in children, reflecting efficiency of ventilation. We recommend expressing OUES values relative to Body Surface Area (BSA) or Fat Free Mass (FFM).

The oxygen uptake efficiency slope: what do we know?

PURPOSE: To summarize what is currently known about the oxygen uptake efficiency slope (OUES) as an objective and independent submaximal measure of cardiorespiratory fitness in health and disease. METHODS: A literature search was performed within the following electronic databases--PubMed, Cochrane Library, Embase, Web of Science, CINAHL, PsycINFO, Scopus, and MEDLINE--using the search terms "OUES," "oxygen uptake efficiency slope," and "ventilatory efficiency." The search identified 51 articles. Selection, evaluation, and data extraction were accomplished independently by 2 authors. RESULTS: Twenty-four studies satisfied all inclusion criteria: 17 cross-sectional studies and 7 intervention studies. The results indicated that the OUES is relatively independent of exercise intensity, correlates highly with other exercise parameters, appears to have discriminative value, and is sensitive to the effects of physical training in patients with cardiac disease. Oxygen uptake efficiency slope values are considerably influenced by anthropometric variables and show large interindividual variation. CONCLUSION: Oxygen uptake efficiency slope is an independent and reproducible measure of cardiorespiratory function that does not require maximal exercise. It greatly reduces test variability because of motivational and subjective factors and is reliable and easily determinable in all subjects. Although OUES appears not interchangeable with maximal parameters of cardiopulmonary function, it seems to be a useful submaximal alternative in subjects unable to perform maximal exercise.

Can peak work rate predict peak oxygen uptake in children with juvenile idiopathic arthritis?

OBJECTIVE: To examine whether peak work rate (W(peak)) can predict peak oxygen uptake (VO(2peak)) in children with juvenile idiopathic arthritis (JIA). METHODS: Ninety-one patients with JIA with a mean +/- SD age of 11.4 +/- 2.9 years underwent a cardiopulmonary exercise test in which VO(2peak) and W(peak) were determined. A multivariate regression model was used to formulate a regression equation to predict VO(2peak) using W(peak) and anthropometric and demographic details. This regression equation was subsequently cross-validated using an unrelated data set from children with JIA (n = 17). RESULTS: The following linear regression equation to predict VO(2peak) was established: VO(2peak) (liters/minute) = 0.308 + 0.146 x sex (0 = female, 1 = male) + 0.005 x weight (kg) + 0.008 x W(peak) (W) (R(2) = 0.91, standard error of the estimate = 0.18 liter/minute). Using this equation, the predicted VO(2peak) was strongly related to the measured VO(2peak) (r = 0.96, P < 0.0001). Bland and Altman analysis revealed a mean difference of 0.01 liter/minute and limits of agreement between -0.35 and 0.35 liter/minute. CONCLUSION: This study suggests that W(peak) is a strong predictor of VO(2peak) in children with JIA and may be used as a surrogate measure of VO(2peak) in situations where it is not possible to formally assess VO(2peak).

Is grip strength a predictor for total muscle strength in healthy children, adolescents, and young adults?

The primary purpose of this study was to examine whether grip strength is related to total muscle strength in children, adolescents, and young adults. The second purpose was to provide reference charts for grip strength, which could be used in the clinical and research setting. This cross-sectional study was performed at primary and secondary schools and the University of Applied Sciences. Three hundred and eighty-four healthy Dutch children, adolescents, and young adults at the age of 8 to 20 years participated. Isometric muscle strength was measured with a handheld dynamometer of four muscle groups (shoulder abductors, grip strength, hip flexors, and ankle dorsiflexors). Total muscle strength was a summing up of shoulder abductors, hip flexors, and ankle dorsiflexors. All physical therapists participated in a reliability study. The study was started when intratester and intertester reliability was high (Pearson correlation coefficient >0.8). Grip strength was strongly correlated with total muscle strength, with correlation coefficients between 0.736 and 0.890 (p < 0.01). However, the correlation was weaker when controlled for weight (0.485-0.564, p < 0.01). Grip strength is related to total muscle strength. This indicates, in the clinical setting, that grip strength can be used as a tool to have a rapid indication of someone's general muscle strength. The developed reference charts are suitable for evaluating muscle strength in children, adolescents, and young adults in clinical and research settings.