Within- and between-day stability of treadmill walking VO2 in children with hemiplegic cerebral palsy. Stability of walking VO2 in children with CP.

Within- and between-day stability in locomotor energy use was quantified in 13 children with hemiplegic CP. During testing, subjects were familiarized with the laboratory environment (Session 1), performed three 5-min level treadmill walks (Trials 1, 2, and 3) at 0.67 m x s-1 (Session 2), and completed a single 5-min walk (Trial 4) at 0.67 m x s-1 (Session 3). In Sessions 2 and 3, HR was assessed and expired air was collected and analyzed to determine VO2. Data analyses revealed no significant difference (P > 0.05) in either net VO2 (ml x kg-1 x min-1) or EEIHR (b x m-1) across the three trials performed in Session 2 and between average measures of net VO2 and EEIHR quantified in Session 2 and those obtained in Session 3. Mean within-day coefficient of variation (CV) values for net VO2 and EEIHR were 8.6% +/- 8.5% and 13.9% +/- 7.8%, respectively. Analysis of between-day variability and energy expenditure revealed a between-day CV value of 13.1% for net VO2 and 24.0% for EEIHR. In addition, significant inverse relationships between GMFM scores and within-day (r = -0.61) and between-day (r = -0.58) CV values for net VO2 were detected. Viewed in concert, these data suggest that fairly stable within- and between-day measures of locomotor energy expenditure during level treadmill walking can be achieved in subjects with hemiplegic CP if testing is preceded by a short period of treadmill accommodation. However, children with greater motor dysfunction may require an extended period of treadmill accommodation to reduce trial-to-trial variability in walking energy use.

Within- and between-day stability of treadmill walking VO2 in children with hemiplegic cerebral palsy, stability of walking VO2 in children with CP.

Within- and between-day stability in locomotor energy use was quantified in 13 children with hemiplegic cerebral palsy (CP). During testing, subjects were familiarized with the laboratory environment (Session 1), performed three 5 min level treadmill walks (Trials 1-3) at 0.67 m*s(-1) (Session 2), and completed a single 5 min walk (Trial 4) at 0.67 m*s(-1) (Session 3). In Sessions 2 and 3, heart rate (HR) was assessed and expired air was collected and analyzed to determine VO2. Data analyses revealed no significant difference (P > 0.05) in either net VO2 (ml kg(-1)*min(-1)) or EEI(HR) (b*m(-1)) across the three trials performed in Session 2 and between average measures of net VO2 and EEI(HR) quantified in Session 2 and those obtained in Session 3. Mean within-day coefficient of variation (CV) values for net VO2 and EEI(HR) were 8.6% +/- 8.5% and 13.9% +/- 7.8%, respectively. Analysis of between-day variability and energy expenditure revealed a between-day CV value of 13.1% for net VO2 and 24.0% for EEI(HR). In addition, significant inverse relationships between Gross Motor Function Measure (GMFM) scores and within- (r = -0.61) and between-day (r = -0.58) CV values for net VO2 were detected. Viewed in concert, these data suggest that fairly stable within- and between-day measures of locomotor energy expenditure during level treadmill walking can be achieved in subjects with hemiplegic CP if testing is preceded by a short period of treadmill accommodation. However, children with greater motor dysfunction may require an extended period of treadmill accommodation to reduce trial-to-trial variability in walking energy use.

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 heartrate (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 x s(-1) to familiarize themselves with treadmill locomotion. During the final session participants walked at 0.67, 0.89, and 1.12m x 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 x s(-1), a moderate relationship (r=0.64; p<0.05) was present between these variables at 1.12m x 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.

Eccentric exercise effect on blood oxidative-stress markers and delayed onset of muscle soreness.

PURPOSE: This study examined the effects of a single bout of high-intensity eccentric exercise (EE) on blood protein carbonyls, glutathione status, and muscle damage indicators to ascertain whether blood markers of oxidative stress are elevated at the time delayed onset of muscle soreness (DOMS) occurs. METHODS: Eight healthy men (26.5 +/- 1.5 yr) performed 60 eccentric contractions at approximately 135-150% dominant arm maximum isometric force (MIF) using their nondominant arm elbow flexors. DOMS, range of motion (ROM), MIF, and blood were obtained before, immediately after, and 24, 48, 72, and 96 h after the EE. Blood samples were analyzed for plasma creatine kinase (CK) activity, and protein carbonyls (PC), and erythrocyte glutathione status. RESULTS: A significant decrease in MIF occurred at all times after the EE. ROM decreased from 24 to 96 h, and DOMS increased 24 to 72 h in the nondominant arm as indicated by a repeated measure ANOVA. Plasma CK activity peaked at 72 h (1620 +/- 500 IU x L(-1)) compared with baseline (154 +/- 27 IU x L(-1). Erythrocyte-reduced glutathione (GSH) concentration was not significantly affected by the EE but tended to decrease 23% by 24 h and continued at this level for 96 h. Oxidized glutathione (GSSG) and total glutathione were unchanged over time. A significant increase in plasma PC occurred at 24 and 48 h after eccentric exercise. CONCLUSIONS: The results suggest that 60 EE at 135-150% MIF can result in DOMS, with decreased muscle function and increases in plasma PC at 24 and 48 h without alterations in blood glutathione status.