Diagnostic quality of Actigraph-based physical activity cut-offs for children: what overweight/obesity references can tell?

BACKGROUND: There is conflicting literature about Actigraph-based cut-off points (CoP) that define the lower limit of moderate-to-vigorous physical activity (MVPA) among children. The aim of the present study was to compare the diagnostic quality of Actigraph-based CoP relative to different body mass index (BMI) classification systems of the weight status of children. METHODS: One hundred and thirteen children aged 8-11 years recruited from three randomly selected elementary schools wore the Actigraph, model 7164 (Actigraph Manufacturing Technology) for 3 days. Five CoP, expressed in counts per minute (c.p.m.; CoP 1000 CoP 2000, CoP 3000, CoP 3200, and CoP 3600) were used to compute their MVPA. The area under the receiver operating characteristic curves (AUC) together with specific indices allowed assessment of the performance of these CoP in reference to overweight/obesity status as defined using BMI-based criteria from the International Obesity Task Force (IOTF), French References (FR) and World Health Organization (WHO) standards. RESULTS: Overweight/obesity frequency ranged from 30% to 42%, with no sex-related difference. All AUC (range, 0.623-0.660) were significantly higher than 0.500 except from those of CoP 1000 and 2000 using the IOTF criteria (0.602 +/- 0.058 and 0.601 +/- 0.057, respectively) and the FR (0.608 +/- 0.060 for CoP 1000). Furthermore, with the WHO standards, all the CoP provided non-significant AUC (range, 0.566-0.597). According to the IOTF and the FR criteria, respectively, CoP 3600 had the highest probability of correct decision (0.62 and 0.68), the lowest misclassification errors (0.38 and 0.32), the highest validity coefficient (0.21 and 0.29), and the highest expected maximum utility (59 and 83). CONCLUSION: When children are classified using BMI-based criteria, the threshold of 3600 c.p.m. should be more appropriate in discriminating non-overweight from overweight/obese.

Prehospital pain treatment: an economic productivity factor in emergency medicine?

RATIONALE AND OBJECTIVES: Analgesia is a recommended practice for pain treatment in prehospital emergency medicine, but all experts note suboptimal pain relief or oligoanalgesia. The increase in the Care Workload (CW) and the Medical Treatment Duration (MTD) linked to analgesia are two explanatory factors, and they are representative of the unavailability of a prehospital team. The unavailability of a team is an opportunity cost which is probably the most important cost within the framework of prehospital emergency. The aim of this study was to analyse the influence of analgesia use on the availability of prehospital emergency teams. METHODS: This study was a prospective, multicentre cohort study conducted in 10 French Mobile Emergency and Resuscitation Services (MERS) between September 2001 and June 2003. A case-control study was performed including 568 case patients who received analgesia matched with controls based on diagnosis and severity. The pairs were compared for MTD and CW. RESULTS: No significant difference between cases and controls was found concerning MTD (P = 0.134). Conversely, a difference was found for CW (P < 10(-4)), with a mean value of 53.7 Project Recherche Nursing (PRN) points for the cases and 45.8 PRN points for the controls. CONCLUSIONS: This study shows that analgesia generates an additional CW without increasing the MTD, and does not hinder the MERS teams' availability. This economic result should improve adherence to these clinical practice guidelines. Thus, analgesia appears to be a factor of productivity in the current context of economic pressures in terms of the funding of the healthcare system.

Actigraph-defined moderate-to-vigorous physical activity cut-off points among children: statistical and biobehavioural relevance.

AIM: To compare Actigraph-defined moderate-to-vigorous physical activity (MVPA) cutpoints among children, combining statistical and biobehavioural analyses. METHODS: One hundred and thirteen children aged 10.0 +/- 0.8 years wore accelerometer for three days. The time they spent in MVPA was estimated using 10 thresholds ranged from 3000 to 3900 cpm. A statistical construct including 45 Bland and Altman pairwise analyses was used to compare the 10 estimates of MVPA. A regression was performed to develop an equation relating mean differences to the between-cutpoint gaps. RESULTS: Mean differences in the MVPA estimates ranged from 1.6 to 12.8 min as a function of increment. Raw estimates of MVPA decreased according to an arithmetic sequence with a common difference of 200 cpm. This difference translates into a drop of 12% in MVPA and a misclassification of up to 5% of children. Mean differences (Y) could be predicted from increments (X) using: Y= 0.02 X (R(2)= 0.99, SEE = 0.72, p < 0.0001). CONCLUSION: When a lack of agreement should be assumed as the between-cutpoint gap exceeds 200 cpm, statistical differences may occur earlier at 90 cpm. Yet, the current equation makes it possible to compare and adjust results from studies/interventions using diverse cutpoints for MVPA among children.

Comparison of the diagnostic quality of body mass index, waist circumference and waist-to-height ratio in screening skinfold-determined obesity among children.

This study compared the diagnostic quality of the body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR) in screening obesity among children, according to gender and maturation. A sample of 65 boys and 57 girls aged from 6.8 to 11.8 years underwent anthropometry and total percentages of body fat (%TBF)--the reference criterion--were obtained by skinfolds. Diagnostic quality was derived from the area under the ROC curve (AUC), sensitivity, specificity, accuracy, and Youden index (YI). In general, AUC ranged 0.80-1.00, with relatively higher values for WC in boys and late maturers. In the aforementioned subgroups, WC and WHtR were more sensitive than BMI. Furthermore, WC was more consistent in terms of the balance between sensitivity and specificity than BMI or WHtR, across gender and maturational status. The YI ranged 0.59-0.92 and 0.58-0.85 according to gender and maturational status, respectively. Higher values of YI were obtained with WC in boys and late maturers. BMI displayed better accuracy values (86.8-95.2%) among boys and early maturers. WHtR was least useful in classifying children's obesity status. Waist circumference exhibits an overall better performance, among boys and late maturers. Paediatricians should systematically add WC to clinical and epidemiological measurements.

Vasopressin and epinephrine vs. epinephrine alone in cardiopulmonary resuscitation.

BACKGROUND: During the administration of advanced cardiac life support for resuscitation from cardiac arrest, a combination of vasopressin and epinephrine may be more effective than epinephrine or vasopressin alone, but evidence is insufficient to make clinical recommendations. METHODS: In a multicenter study, we randomly assigned adults with out-of-hospital cardiac arrest to receive successive injections of either 1 mg of epinephrine and 40 IU of vasopressin or 1 mg of epinephrine and saline placebo, followed by administration of the same combination of study drugs if spontaneous circulation was not restored and subsequently by additional epinephrine if needed. The primary end point was survival to hospital admission; the secondary end points were return of spontaneous circulation, survival to hospital discharge, good neurologic recovery, and 1-year survival. RESULTS: A total of 1442 patients were assigned to receive a combination of epinephrine and vasopressin, and 1452 to receive epinephrine alone. The treatment groups had similar baseline characteristics except that there were more men in the group receiving combination therapy than in the group receiving epinephrine alone (P=0.03). There were no significant differences between the combination-therapy and the epinephrine-only groups in survival to hospital admission (20.7% vs. 21.3%; relative risk of death, 1.01; 95% confidence interval [CI], 0.97 to 1.05), return of spontaneous circulation (28.6% vs. 29.5%; relative risk, 1.01; 95% CI, 0.97 to 1.06), survival to hospital discharge (1.7% vs. 2.3%; relative risk, 1.01; 95% CI, 1.00 to 1.02), 1-year survival (1.3% vs. 2.1%; relative risk, 1.01; 95% CI, 1.00 to 1.02), or good neurologic recovery at hospital discharge (37.5% vs. 51.5%; relative risk, 1.29; 95% CI, 0.81 to 2.06). CONCLUSIONS: As compared with epinephrine alone, the combination of vasopressin and epinephrine during advanced cardiac life support for out-of-hospital cardiac arrest does not improve outcome. (ClinicalTrials.gov number, NCT00127907.)

Physical activity and sedentary lifestyle in children as time-limited functions: usefulness of the principal component analysis method.

This study was designed to examine the hourly variation in and the interplay between physical activity and sedentary behavior (SB) in order to highlight key time periods for physical activity interventions for children. Data for physical activity and SB obtained with ActiGraph in 56 boys and 47 girls aged from 8 to 11 years. These data were divided into sixty minute-time samples for moderate-to-vigorous physical activity (MVPA) and SB, and analyzed using a principal component analysis (PCA) and correlation statistics. The PCA provides 10 factors which account for 80.4% of the inertia. Only two of these factors did not display competition between MVPA and SB. Contrary to some reports, a coefficient of correlation of -.68 (p < 10(-4)) was found between daily time spent at MVPA and SB. Some salient traits of children's behaviors were shown through PCA. The results suggested that efficacy of interventions targeting the morning hours (07:00 AM-11:59 AM) and the afternoon period (02:00 PM-05:59 PM) warrants attention.

Methodological approach for the evaluation of the performances of medical intensive care units.

PURPOSE: The purpose of the study was to present a methodological approach enabling the comparison of clinical and economic performances of intensive care units and a graphical visualization based on these 2 dimensions. PATIENTS AND METHODS: A retrospective analysis of a database of 666 patients admitted in intensive care units over a period of 2 consecutive months. RESULTS: Calculation of clinical performance is based on the difference between the mortality observed and forecast from the Simplified Acute Physiology Score version 2. The evaluation of resource consumption is carried out from the measure of medical and paramedical care workload. These 2 scores are modeled on the basis of the length of stay and the severity state of the patient. The economic performance is calculated on the basis of the difference between the resource consumption observed and forecast. The graphs are constructed by taking up as coordinates the values of the clinical and economic performances of each center. CONCLUSION: These graphs enable the identification of the most deviating intensive care units to study, for example, their organizational, technical, or human resource setup accounting for their position.

Moderate-to-vigorous physical activity among children: discrepancies in accelerometry-based cut-off points.

OBJECTIVE: To highlight the discrepancies in accelerometry cut-off points of moderate-to-vigorous physical activity (MVPA) according to the definitions of Puyau et al. (MVPA(P)) and Trost et al. (MVPA(T)). RESEARCH METHODS AND PROCEDURES: Forty-five children from 8 to 11 years old were monitored with the ActiGraph (ActiGraph, LLC, Fort Walton Beach, FL) for 3 consecutive days. Daily time spent at MVPA obtained with MVPA(P) was compared with that obtained with MVPA(T) using variability, regression, and agreement statistics. Data were then discussed with regard to physical activity recommendations. RESULTS: The mean daily time spent at MVPA(P) (28 +/- 18 minutes) was significantly lower (p < 10(-4)) than that spent at MVPA(T) (141 +/- 39 minutes). The coefficient of determination between the two definitions was low (R(2) = 0.49 +/- 0.71). There was a lack of agreement between the two definitions, with a mean error or bias of 113 min/d. Thirty-four point eight percent and 100% of children underwent 30-minute MVPA/d with MVPA(P) and MVPA(T) definitions, respectively. DISCUSSION: Comparability between studies devoted to describing children's physical activity or to assessing interventions may lack consistency according to the definition, with a real risk of misclassification.

Relationship between oxygen uptake kinetics and performance in repeated running sprints.

The purpose of this study was to test the hypothesis that subjects having a shorter time constant for the fast component of VO2 kinetics in a transition from rest to constant exercise would maintain their speed for a longer time during repeated sprint exercise (RSE). Eleven male soccer players completed a graded test, two constant exercises at 60% maximal aerobic speed and RSE, consisting of fifteen 40-m sprints alternated with 25 s of active recovery. All the tests were performed on the field (200 m indoor track). The parameters of the VO2 kinetics (time delay, time constant, and amplitude of the primary phase) during the two constant exercises were modeled. All subjects elicited VO2 during the RSE. A significant correlation was found between VO2 and the relative decrease in speed during the 15 sprints (r=0.71; p < 0.05), but not between VO2 and the cumulated time for the 15 sprints (r=0.48; p > 0.05). There were significant correlations between the time constant of the primary phase and the relative decrease in speed during the 15 sprints (r=0.80; p < 0.01) and the cumulated time for the 15 sprints (r=0.80; p < 0.01). These results suggest that individuals with faster VO2 kinetics during constant load exercise might also have a faster adjustment of VO2 during RSE leading to a shorter cumulated time and a lower relative decrease in speed during the 15 sprints.

High-intensity intermittent running training improves pulmonary function and alters exercise breathing pattern in children.

We investigated the effects of short duration running training on resting and exercise lung function in healthy prepubescent children. One trained group (TrG) (n = 9; three girls and six boys; age = 9.7 +/- 0.9 year) participated in 8 weeks of high-intensity intermittent running training and was compared to a control group (ContG) (n = 9; four girls and five boys; age = 10.3 +/- 0.7 year). Before and after the 8-week period, the children performed pulmonary function tests and an incremental exercise test on a cycle ergometer. After the 8-week period, no change was found in pulmonary function in ContG. Conversely, an increase in forced vital capacity (FVC) (+7 +/- 4% ; P = 0.026), forced expiratory volume in one second (+11 +/- 6% ; P = 0.025), peak expiratory flows (+17 +/- 4% ; P = 0.005), maximal expiratory flows at 50% (+16 +/- 10% ; P = 0.019) and 75% (+15 +/- 8% ; P = 0.006) of FVC were reported in TrG. At peak exercise, TrG displayed higher values of peak oxygen consumption (+15 +/- 4% ; P < 0.001), minute ventilation (+16 +/- 5% ; P = 0.033) and tidal volume (+15 +/- 5% ; P = 0.019) after training. At sub-maximal exercise, ventilatory response to exercise DeltaV(E)/DeltaV(CO(2)) was lower (P = 0.017) in TrG after training, associated with reduced end-tidal partial oxygen pressure (P < 0.05) and higher end-tidal partial carbon dioxide pressure (P = 0.026). Lower deadspace volume relative to tidal volume was found at each stage of exercise in TrG after training (P < 0.05). Eight weeks of high-intensity intermittent running training enhanced resting pulmonary function and led to deeper exercise ventilation reflecting a better effectiveness in prepubescent children.

Relationship Between the MTI Accelerometer (Actigraph) Counts and Running Speed During Continuous and Intermittent Exercise.

This study was designed to investigate the relationship between Actigraph counts and running speed; and to describe differences due to accelerometer position on the body and due to exercise modality. Eleven physical education students (age, 25.1 ± 3.7 years; height, 1.73 ± 0.10 m; body mass, 70.8 ± 10.8 kg) completed two exhaustive exercise tests (continuous and intermittent), with MTI accelerometers mounted both at the hip and ankle. Exercise consisted of running for 3-min at incremental speeds until volitional exhaustion. During both exercise tests, the relationship between the ActiGraph outputs worn at the hip and speed was linear in the range 1.1 - 3.3 m·s(-1) (r(2) = 0.94 and 0.95, p < 0.01 for continuous and intermittent exercise respectively). A coefficient of determination of r(2) = 0.97 (p < 0.01) was found with ankle wearing from walking, jogging and running at high speeds. There was a body placement effect at all absolute speeds (p < 0.01); but no exercise effect on accelerometer counts and no interaction between placement and exercise (p> 0.05). The ActiGraph seems to be a reliable tool for estimating a wide range of activity or exercise intensities. An ActiGraph worn at the ankle may be more appropriate to reflect normal human movement. Key PointsActigraph counts are not influenced by the type of activity.The levelling off of Actigraph output depends mainly on its location on the body, and does not reflect a lack of sensivity at higher speeds.The ActiGraph can be an alternative tool to estimate activity intensity in various conditions.

Effects of a short-term interval training program on physical fitness in prepubertal children.

The aim of this study was to analyze the effects of a 7-week interval-training program on different aspects of physical fitness in children who were 8-11 years old. Forty-six boys and 54 girls (9.7 +/- 0.8 years) were divided into an experimental group and a control group. The 2 groups performed selected tests from the European physical fitness test battery before and after training. Training consisted of 2 specific 30-minute sessions per week of short high-intensity, intermittent-running aerobic exercises at velocities ranging from 100-130% of maximal aerobic speed. After training, the experimental group demonstrated a significant improvement in the standing broad jump (9.6%, p < 0.001, F = 12.9) and 20-meter shuttle run (5.4%, p < 0.001, F = 14.4), whereas for the control group, no significant changes were observed. It was concluded that a high-intensity, intermittent-running program improved children's aerobic performance and explosive strength.

Passive versus active recovery during high-intensity intermittent exercises.

PURPOSE: To compare the effects of passive versus active recovery on muscle oxygenation and on the time to exhaustion for high-intensity intermittent exercises. METHODS: Twelve male subjects performed a graded test and two intermittent exercises to exhaustion. The intermittent exercises (15 s) were alternated with recovery periods (15 s), which were either passive or active recovery at 40% of .VO2max. Oxyhemoglobin was evaluated by near-infrared spectroscopy during the two intermittent exercises. RESULTS: Time to exhaustion for intermittent exercise alternated with passive recovery (962 +/- 314 s) was significantly longer (P < 0.001) than with active recovery (427 +/- 118 s). The mean metabolic power during intermittent exercise alternated with passive recovery (48.9 +/- 4.9 mL.kg-1.min-1) was significantly lower (P < 0.001) than during intermittent exercise alternated with active recovery (52.6 +/- 4.6 mL.kg-1.min-1). The mean rate of decrease in oxyhemoglobin during intermittent exercises alternated with passive recovery (2.9 +/- 2.4%.s-1) was significantly slower (P < 0.001) than during intermittent exercises alternated with active recovery (7.8 +/- 3.4%.s-1), and both were negatively correlated with the times to exhaustion (r = 0.67, P < 0.05 and r = 0.81, P < 0.05, respectively). CONCLUSION: The longer time to exhaustion for intermittent exercise alternated with passive recovery could be linked to lower metabolic power. As intermittent exercise alternated with passive recovery is characterized by a slower decline in oxyhemoglobin than during intermittent exercise alternated with active recovery at 40% of .VO2max, it may also allow a higher reoxygenation of myoglobin and a higher phosphorylcreatine resynthesis, and thus contribute to a longer time to exhaustion.