Daniel J. Keefer

Comparison of direct and indirect measures of walking energy expenditure in children with hemiplegic cerebral palsy

The purpose of this study was to investigate the use of the heart‐rate (HR) version of the energy expenditure index (EEIHR) as a proxy for measurement of walking oxygen consumption (VO2) in children with cerebral palsy (CP). Thirteen children (eight males, five females; mean age 11 years 2 months [SD 3 years], age range 6 to 15 years) with hemiplegic CP, participated in this study. The study was conducted over three sessions. During session 1, participants were familiarized with testing procedures and given 5 minutes of treadmill walking practice. In session 2, participants completed three 5‐minute walking bouts on the treadmill at 0.67m˙s‐1 to familiarize themselves with treadmill locomotion. During the final session participants walked at 0.67, 0.89, and 1.12m˙s‐1 for 5 minutes while gross oxygen consumption (gross VO2; walking VO2/speed), net VO2 ([walking VO2‐resting VO2]/speed), and EEIHR ([walking HR‐resting HR]/speed) were measured during the last 2 minutes of each bout. Correlational analyses indicated no relationship (p>0.05) between measures of gross VO2 and EEIHR at each speed. Although no association was evident between net VO2 and EEIHR at 0.67 and 0.89m˙s‐1, a moderate relationship (r=0.64;p < 0.05) was present between these variables at 1.12m˙s‐1. Examination of individual data revealed that most participants displayed an unmatched pattern of response between net VO2 and EEIHR. Our results suggest that caution should be applied when using EEIHR to estimate walking energy expenditure in children with CP.

Identification of a Core Set of Exercise Tests for Children and Adolescents with Cerebral Palsy: A Delphi Survey of Researchers and Clinicians.

Aim  Evidence‐based recommendations regarding which exercise tests to use in children and adolescents with cerebral palsy (CP) are lacking. This makes it very difficult for therapists and researchers to choose the appropriate exercise‐related outcome measures for this group. This study aimed to identify a core set of exercise tests for children and adolescents with CP.

Identification of a core set of exercise tests for children and adolescents with cerebral palsy

Aim  Evidence‐based recommendations regarding which exercise tests to use in children and adolescents with cerebral palsy (CP) are lacking. This makes it very difficult for therapists and researchers to choose the appropriate exercise‐related outcome measures for this group. This study aimed to identify a core set of exercise tests for children and adolescents with CP.

Longitudinal profiles of oxygen uptake during treadmill walking in able-bodied children: the locomotion energy and growth study

The purpose of this study was to document age-related changes in walking V(O(2)) in able-bodied boys and girls. Beginning at age 6 and ending at age 10, 23 children (14 girls, 9 boys) performed six 5-min bouts of level treadmill walking at 0.67, 0.89, 1.12, 1.34, 1.56, and 1.79 m s(-1) on an annual basis. Prior to data collection, subjects received 60 min of treadmill walking practice. During the last 2 min of each walking bout, a 2-min sample of expired air was collected in a meteorological balloon and analyzed to determine V(O(2)). Averaged across age, interindividual variation in V(O(2)) ranged from 32 to 41%. Repeated-measures analysis of variance demonstrated a speed by age interaction for V(O(2)), such that mean V(O(2)) rose (P< or = 0.05) across the five fastest speeds for 6-, 7-, 8-, and 10-year olds and increased over the entire speed range for 9-year olds. For all speeds, V(O(2)) decreased yearly from the ages of 6 to 8. When averaged across speeds, V(O(2)) was 27% higher for 6-year olds compared with 10-year olds. From a clinical perspective, access to longitudinal measurements of walking V(O(2)) in able-bodied children should be helpful in interpreting gait energy use in children with movement disorders and evaluating treatment strategies designed to reduce the aerobic demand of locomotion in youth with impaired mobility.

Electromyographic (EMG) analysis of quadriceps muscle fatigue in children with cerebral palsy during a sustained isometric contraction.

The purpose of this investigation was to determine whether changes in surface electromyography (EMG) data during an isometric muscle protocol, in combination with maximal voluntary isometric force, provide information on fatigue occurrence and exercise limitation in children with cerebral palsy. Twelve children with cerebral palsy and 10 age-matched controls completed an assessment of quadriceps muscle fatigue on an isokinetic device with surface EMG measurements, during a sustained isometric contraction at 50% of the maximal voluntary isometric force. The EMG data collected in participants with cerebral palsy suggest that muscle fatigue occurred sooner in children with cerebral palsy relative to the age-matched controls. However, the results demonstrate that no difference was found in time to exhaustion between the able-bodied and participants with cerebral palsy. These contrasting results may be the result of spasticity and co-contraction during maximal testing, which may play an important role in exercise limitation in children with cerebral palsy.

Waist‐to‐Height Ratio and Body Mass Index as Indicators of Cardiovascular Risk in Youth

BACKGROUND The purpose of this investigation was to determine if waist-to-height ratio (WHTR) or body mass index (BMI) is the better indicator of cardiovascular disease risk in children and adolescents of varying ages. METHODS Data from children and adolescents (N = 2300) who were part of the 2003-2004 National Health and Nutrition Examination Survey (NHANES) were analyzed. Chi-square analyses (2 × 2) were used to compare risk levels of WHTR (>0.50) and BMI (>85th percentile) to systolic blood pressure (SBP) (>90th percentile) as well as total cholesterol (TC) (>200 mg(.) dL(-1) ) for the entire cohort and specified age groups. RESULTS Significant relationships were detected between SBP and WHTR and BMI, respectively, for the entire cohort as well as the 2 oldest subsamples. A significant association was also noted for both WHTR and BMI to TC for the entire sample and the eldest age group. CONCLUSIONS A significant association was observed between indicators of cardiovascular health risk and both WHTR and BMI in the entire NHANES cohort of boys and girls as well as in the older age groups. The younger groups of participants did not display a notable link between these cardiovascular indicators and WHTR or BMI.

METABOLIC ACCOMMODATION OF YOUNG CHILDREN TO TREADMILL WALKING 1167

Few data exist concerning the reproducibility of stable oxygen uptake (VO(2)) values during level treadmill walking in young able-bodied children. To address this issue, 41 able-bodied 6-year-olds (19 boys, 22 girls, X height=117.2+/-4.7 cm, X body mass=21.8+/-2.5 kg) were tested on two occasions. In session 1, subjects were familiarized with the laboratory environment and performed 5 min of level treadmill walking at 1.34 m s(-1). During session 2, each child completed 30 min (three 10-min trials) of level treadmill walking at 1.34 m s(-1). For each 10-min trial, mean VO(2) was determined by averaging VO(2) values obtained from analysis of two 2-min expired gas samples. While the mean VO(2) for trial 1 was higher than values recorded for trials 2 and 3, effect sizes corresponding to these differences were low (</=0.16). Average within subject coefficient of variation and intraclass reliability coefficient values for VO(2) across the three walking trials were 2. 0+/-1.5% and 0.96, respectively. Viewed collectively, these results suggests that among young able-bodied children, acceptably and reproducible stable VO(2) values during level treadmill walking can be obtained within 10 min if data collection is preceded by exposure to testing procedures and a brief period of treadmill walking practice.