Joyce Obeid

Accelerometry: a feasible method to quantify physical activity in ambulatory and nonambulatory adolescents with cerebral palsy.

Objective. To determine the feasibility of physical activity monitoring in adolescents with cerebral palsy (CP). Methods. A convenience sample of ambulatory and non-ambulatory adolescents (N = 23; 17 males, 6 females; mean age 13.5 y, SD 2.6 y; Gross Motor Function Classification System (GMFCS) distribution: n = 9 Level I, n = 5 Level II, n = 5 Level III, n = 4 Level IV) was recruited. Physical activity (PA) was objectively assessed using the ActiGraph GT1M activity monitor. Discomfort or adverse effects of wearing the accelerometers were recorded by participants. Levels of physical activity were determined as total PA, light PA (LPA), moderate PA (MPA), moderate-to-vigorous (MVPA), and vigorous PA (VPA) using cut-points recently validated for CP. Results. Most participants showed little reluctance. Mean daily MVPA for all participants was 30.7 minutes (SD 30.3), which corresponded to 2.7 (SD 2.4) minutes of MVPA per hour or 4.5% (SD 3.9) of the total monitoring time. Total PA and MVPA were greatest in ambulatory youth (GMFCS levels I and II) compared with youth who use a walking aid or wheelchair (GMFCS levels III and IV) (P < 0.05). Conclusion(s). The results support the use of the accelerometer as a feasible and useful measure of activity in ambulatory and nonambulatory adolescents with CP.

Objectively Measured Sedentary Time in Youth With Cerebral Palsy Compared With Age-, Sex-, and Season-Matched Youth Who Are Developing Typically: An Explorative Study

Background Children with cerebral palsy (CP) demonstrate reduced physical activity levels compared with children with typical development. Sedentary behavior, including the duration and frequency of sedentary bouts, has not yet been objectively examined in this population but may have clinical implications for the development of secondary health complications. Objective The aim of this study was to identify time spent sedentary and frequency of breaks interrupting sedentary time in youth with CP compared with youth without CP. It was hypothesized that individuals with CP would spend more hours sedentary than their peers and take fewer breaks to interrupt sedentary time. Design This was a cross-sectional, prospective study. Methods A convenience sample of 17 ambulatory children with CP (15 boys and 2 girls) (mean age=13.0 years, SD=2.2) and 17 age-, sex-, and season-matched youth who were developing typically (TD group) (mean age=12.9 years, SD=2.5) wore an accelerometer over a 7-day period. Sedentary time (in minutes) and number of breaks from sedentary time, corrected for monitoring and sedentary time, respectively, were examined. Differences between groups were determined with an independent-samples t test. Results Children with CP engaged in significantly more sedentary time (X̅=47.5 min/h, SD=4.9) compared with the TD group (X̅=43.6 min/h, SD=4.2), with significantly fewer breaks from sedentary time (CP group: X̅=179, SD=70; TD group: X̅=232 breaks/h sedentary, SD=61). Limitations The sample included only ambulatory youth with CP, classified as Gross Motor Function Classification System levels I to III. Conclusions Sedentary time was higher in the CP group and was characterized by less frequent breaks compared with the TD group. Future research should examine the extent to which sedentary time is associated with cardiovascular and metabolic risk in youth with CP.

Validity of the muscle power sprint test in ambulatory youth with cerebral palsy.

Purpose: To validate the Muscle Power Sprint Test (MPST) against the Wingate Anaerobic cycling Test (WAnT) in a group of youth with cerebral palsy (CP). Methods: Twenty children and adolescents (11 boys and 9 girls; mean age = 14.8 years) with spastic CP, and classified as either level I or II of the Gross Motor Function Classification System, completed the study. Results: Very strong significant correlations were seen for peak power (PP) and mean power (MP) from the MPST and WAnT PP and MP values (PP: r = 0.731, P < .001; MP: r = 0.903, P < .001). Conclusions: The results of this study show that the MPST is a valid test for measuring anaerobic capacity in children with CP, and that this test can be used as an evaluation tool for anaerobic performance in exercise interventions focusing on children and adolescents with CP who are able to walk or run independently.

Exercise and Inflammation in Pediatric Crohn’s Disease

We examined inflammatory cells, cytokines and growth factors in response to acute bouts of moderate intensity continuous exercise and high intensity intermittent exercise in youth with Crohns disease and in healthy matched-controls. 15 patients and 15 controls performed 30 min of cycling at 50% of peak mechanical power (PMP) and 6 bouts of 4×15-s of cycling at 100% PMP. Blood was collected at rest, at the mid-point, at the end of exercise and at 30 and 60 min into recovery. In patients with CD, both types of exercise increased immune cells and GH and decreased IGF-I. Moderate intensity exercise induced a greater increase in leukocytes (p<0.05), neutrophils (p<0.05), lymphocytes (p<0.001), monocytes (p<0.05), IL-6 (p<0.05), IL-17 (p<0.05) and GH (p<0.05) and a similar decrease in IGF-I, compared with high intensity exercise. TNF-α did not change significantly with either exercise. Responses in patients were similar compared with controls; however, in patients monocytes remained elevated significantly longer in response to MICE. Youth with Crohns disease can engage in distinctly different types of exercise without a significant acute exacerbation of inflammation.

Short-term muscle power and speed in preschoolers exhibit stronger tracking than physical activity

The purpose of this study was to examine the tracking of short-term muscle power, speed, and physical activity over a 15-month period in a sample of healthy Canadian preschool-aged children. Seventeen preschoolers (age, 4.4 ± 0.8 years) completed exercise testing and physical activity monitoring at baseline and follow-up separated by 14.6 ± 4.1 months. Short-term muscle power was measured using a modified 10-s Wingate test with peak power and mean power normalized to body mass. Speed was assessed with a 25-m dash. Physical activity was measured by accelerometry (Actigraph GT1M) using a 3-s epoch over 7 consecutive days. Total physical activity and moderate-to-vigorous physical activity, expressed as a percentage of accelerometer wear time, were examined. Tracking of the variables between year 1 and year 2 was analyzed using Spearman rank order correlations and Kappa statistics. Paired t-tests were used to assess differences in performance and physical activity between year 1 and year 2. Total physical activity was not significantly different at year 2 (p > 0.05) and showed fair tracking (r = 0.51, p = 0.05; ĸ = 0.30). Moderate-to-vigorous physical activity was increased at year 2 (p = 0.03) and exhibited poor tracking (r = 0.29, p = 0.28; ĸ = 0.00). Short-term muscle power and speed was increased at year 2 (p < 0.0001) and exhibited significant tracking: peak power (r = 0.72, p = 0.001; ĸ = 0.46), mean power (r = 0.83, p = 0.00004; ĸ = 0.82), and 25-m dash (r = 0.82, p = 0.0001; ĸ = 0.47). Moderate-to-vigorous physical activity increased in this sample of boys and girls during the preschool years, and short-term muscle power and speed exhibited stronger tracking than physical activity.

Reliability and validity of short-term performance tests for wheelchair-using children and adolescents with cerebral palsy

To investigate the test–retest reproducibility of the Muscle Power Sprint Test (MPST), the 10 × 5‐m sprint test, and the arm‐cranking Wingate Anaerobic Test (WAnT) in children and adolescents with cerebral palsy (CP). A secondary objective was to assess the construct validity of the MPST.

Reproducibility of computer-assisted joint alignment measurement in OA knee radiographs

OBJECTIVES (1) To investigate the reproducibility of computer-assisted measurements of knee alignment angle (KA) from digitized radiographs of osteoarthritis (OA) participants requiring total knee arthroplasty (TKA) and (2) to determine whether landmark choice affects the precision of KA measurements on radiographs. METHODS Using a custom algorithm, femoral, central, and tibial measurement-guiding rules were interactively placed on digitized posteroanterior fixed-flexion knee radiographs by mouse control and positioned according to different anatomic landmarks. The angle subtended by lines connecting these guiding rules was measured by three readers to assess interobserver, intraobserver and experience-inexperience reproducibility. Test-retest reproducibility was evaluated with duplicate radiographs from a healthy cohort. Reproducibility was assessed using root-mean square coefficients of variation (RMSCV%). The Bland-Altman method was performed on data obtained from varying anatomic landmarks (confidence interval, CI= 95%). RESULTS From 16 healthy and 30 TKA participants, reproducibility analyses revealed a high degree of intraobserver (n=38, RMSCV=0.56%), interobserver (n=38, RMSCV=0.72%), test-retest (n=16, RMSCV=0.87%) and experience-inexperience (n=38, RMSCV=0.73%) reproducibility with variances below 1%. Varying the orientation of tibial and femoral rules according to anatomic landmarks produced a difference that exceeded an a priori limit of agreement of -1.11 degrees to +1.67 degrees. CONCLUSION Our custom-designed software provides a robust method for measuring KAs within digitized knee radiographs. Although test-retest analyses were only performed in a healthy cohort, we anticipate a similar degree of reproducibility in an OA sample. A standardized set of anatomic landmarks employed for KA measurement is recommended since arbitrary selection of landmarks resulted in imprecise KA measurement even with a computer-assisted technique.

Fitness and physical activity in youth with type 1 diabetes mellitus in good or poor glycemic control.

Patients with type 1 diabetes mellitus (T1DM) may experience poor muscle health as a result of chronic hyperglycemia. Despite this, muscle function in children with T1DM with good or poor glycemic control has yet to be examined in detail.

Effect of milk consumption on rehydration in youth following exercise in the heat

Low-fat milk is thought to be an effective postexercise rehydration beverage in adults; however, little is known about milks rehydration ability in children after exercising in the heat. This study tested the hypothesis that because of its electrolyte and protein content, skim milk (SM) would be more effective than both water (W) and a carbohydrate/electrolyte solution (CES) in replacing body fluid losses in children following exercise in the heat. Thirty-eight (19 females) heat-acclimated pre- to early pubertal (PEP, aged 7-11 years) and mid- to late-pubertal (MLP, aged 14-17 years) children performed 3 sessions in 34.5 °C, 47.3% relative humidity, consisting of 2 × 20-min cycling bouts at 60% peak oxygen uptake followed by consumption of either W, CES, or SM. Each beverage was consumed immediately after exercise in a volume equal to 100% of their body mass loss during exercise. Urine samples were collected before, during, and after exercise, as well as the 2-h period following beverage consumption. On average, children dehydrated 1.3% ± 0.4%. Children ingested 0.40 ± 0.11 L (PEP) and 0.74 ± 0.20 L (MLP) of fluid. The fraction of the ingested beverage retained at 2 h of recovery was greater with SM (74% ± 18%) than W (47% ± 26%) and CES (59% ± 20%, p < 0.001 for both), and greater in CES than W (p < 0.001). All participants were in a hypohydrated state after 2 h of recovery, following the pattern SM < CES < W. In both PEP and MLP children, SM is more effective than W and CES at replacing fluid losses that occur during exercise in the heat.

Inflammatory and growth factor response to continuous and intermittent exercise in youth with cystic fibrosis

BACKGROUND Children with cystic fibrosis (CF) tend to suffer from chronic systemic inflammation and may have impaired growth associated with muscle catabolism. Therefore, investigating which type of exercise can elicit an anabolic response with minimal inflammation is of clinical value. METHODS Twelve children with CF (mean±SD; age: 14.7±2.3 years, predicted FEV(1): 90.0±21.6%) and biological age-matched controls (age: 13.9±2.1 years) completed moderate-intensity, continuous exercise (MICE) and high-intensity, intermittent exercise (HIIE) on separate days. During each exercise, blood was drawn at various time points and analyzed for immune cells, inflammatory cytokines, and growth mediators. RESULTS At rest, children with CF had higher concentrations of neutrophils and IL-6 compared with controls. In children with CF, HIIE did not affect immune cell subsets or cytokines: TNF-α, IL-6, and tumor necrosis factor-like weak inducer of apoptosis (TWEAK). All immune cell subsets and IL-6 increased significantly with MICE in both groups. Growth hormone (GH) increased with both types of exercise, with a greater change from rest during MICE. CONCLUSIONS HIIE was a sufficient stimulus to increase GH in children with CF, without affecting systemic inflammation.