Who will guard the guardians? Cross-sectional study on prevalence of psychiatric morbidity, quality of life, and coping skills in caregivers of children with thalassemia major.

BACKGROUND: Patients of thalassemia major require frequent hospitalization. Caregivers are more affected than the patient themselves as they better appreciate the magnitude of illness and treatment, resulting in increased risks for psychiatric illness. AIMS AND OBJECTIVES: The purpose of the study was to assess the prevalence of psychiatric morbidity in the caregivers of patients with thalassemia major. The study also examined the quality of life of the caregivers, their coping strategies, and its association with sociodemographic variables. METHODOLOGY: A cross-sectional study with 100 caregivers, recruited by convenience sampling technique, attending the thalassemia daycare center, was carried out over 12 months in a tertiary care hospital. They were administered a semistructured proforma along with General Health Questionnaire 12 (GHQ 12), WHO-Quality of Life-BREF (WHO-QOL-BREF), and Coping Inventory for Stressful Situations 21 scale. The GHQ 12 was used for screening and those scoring three or more underwent a clinical psychiatric interview. Those who were diagnosed with psychopathology were ascribed diagnosis as per ICD-10. Descriptive analysis was done. Associations were studied using Fischer's exact test. Comparison of quality of life with blood transfusion variables was done using Mann-Whitney U test. RESULTS: The prevalence of psychiatric morbidity amongst the caregivers was found to be 35% with depressive episode (22%) being the most common. Psychiatric morbidity was found to have a significant association with both, the frequency (P = 0.037) and total number of blood transfusions (P = 0.012). Coping was found to have a strong association with psychiatric morbidity (P = 0.001) and employment (P = 0.009). CONCLUSIONS: Caregivers of children with thalassemia major face psychological burden like depression or anxiety, for which treatment is not sought. Improved psychological health of the caregivers will ensure better care of the child and guarantee better adherence to the treatment.

Regional and global left ventricular function following a simulated 5 km race in sports-trained adolescents.

The effects of a short, high-intensity bout of exercise on cardiac systolic and diastolic function are not well understood in adolescent athletes. Consequently, the aims of the study were to evaluate global left ventricular (LV) systolic and diastolic function, as well as segmental wall motion responses (cardiac strain), prior to as well as 45 and 225 min following a simulated 5 km cross-country race. Twenty trained, adolescent males (age: 15.2 ± 0.7 years) volunteered for exercise testing. LV fractional shortening and the ratio of early (E) and late (A) peak flow velocities reflected global systolic and diastolic function, respectively. Peak longitudinal mitral annular septal tissue velocities were also determined during systole and diastole. Longitudinal strain (ε) and strain rates were determined across the LV. LV fractional shortening was significantly (P < 0.05) higher at 225 min post-race (37.6 ± 5.8%) compared to pre-race (34.5 ± 4.7%) and 45 min post-race (34.9 ± 5.4 %). This difference was abolished after adjusting for post-race heart rates. There was a significant (P < 0.05) decrease in the E:A ratio at both 45 min (2.04 ± 0.57) and 225 min post-race (2.20 ± 0.66) compared to the pre-race value (2.80 ± 0.68). When these data were adjusted for post-race heart rates, these pre-post-race differences in E:A ratio were abolished. There were no significant alterations in either tissue Doppler velocities or longitudinal ε. The evidence suggests that a 5 km race does not lead to any significant post-exercise attenuation in global or regional LV systolic and diastolic function in trained adolescents.

The oxygen uptake kinetic response to moderate intensity exercise in overweight and non-overweight children.

OBJECTIVE: To compare the phase II oxygen uptake time constant (τV'O(2)) and V'O(2) mean response time (V'O(2)MRT) in overweight (OW) and non-OW (NO) children during moderate intensity exercise. DESIGN: Between subjects where participants completed a maximal ramp exercise test on an electromagnetically braked cycle ergometer to determine peak V'O(2) (V'O(2peak)) and gas exchange threshold (GET). Gas exchange was measured breath-by-breath using a mass spectrometer. On subsequent visits, 6 square-wave transitions (2 per day) from 0 W to 90% GET were completed. Individual phase II τV'O(2) and V'O(2)MRTs were estimated from time aligned average V'O(2) traces. SUBJECTS: Eleven OW (11.8±0.4 years) and 12 NO (11.9±0.4 years) children were recruited to the study. The OW group was significantly heavier (62.9±9.7 vs 39.4±5.8 kg, P<0.001), taller (1.58±0.05 vs 1.47±0.07 m, P<0.001) and had a higher body mass index (25.8±3.4 vs 18.3±1.8 kg m(-2), P<0.001). RESULTS: Both τV'O(2) (30.2±9.6 vs 22.8±7.1 s, P<0.05) and V'O(2)MRT (43.5±10.7 vs 36.3±5.3 s, P<0.05) were significantly slower in OW compared with NO children; absolute V'O(2peak) was higher in the OW compared with NO group (2.23±0.04 vs 1.74±0.04 l min(-1), P<0.05); mass relative V'O(2peak) was lower in OW compared with NO children (35.9±8.3 vs 43.8±6.2 ml kg(-1) min(-1), P<0.05); allometrically scaled V'O(2peak) was similar between OW and NO groups whether relative to body mass(0.67) (139.8±29.1 vs 147.2±23.9 ml kg(-67) min(-1)) or stature(3) (576.0±87.2 vs 544.9±84.9 ml m(-3) min(-1)) (P>0.05); absolute V'O(2) at GET was similar between OW and NO groups (0.94±0.24 vs 0.78±0.27 l min(-1), P>0.05); GET expressed as percentage of V'O(2peak) was similar between the groups (42.0±0.1 vs 44.8±0.1%, P>0.05). CONCLUSION: These findings demonstrate impairment in the factors determining V'O(2) kinetics in OW children at a relatively young age. Furthermore, assessment of cardiorespiratory fitness using peak exercise values is likely to be misleading and not useful when designing exercise programmes for OW children.

Skin microvascular reactivity in trained adolescents.

Whilst endothelial dysfunction is associated with a sedentary lifestyle, enhanced endothelial function has been documented in the skin of trained individuals. The purpose of this study was to investigate whether highly trained adolescent males possess enhanced skin microvascular endothelial function compared to their untrained peers. Seventeen highly and predominantly soccer trained boys (V(O)(2)(peak): 55 +/- 6 mL kg(-1) min(-1)) and nine age- and maturation-matched untrained controls (V(O)(2)(peak): 43 +/- 5 mL kg(-1) min(-1)) aged 13-15 years had skin microvascular endothelial function assessed using laser Doppler flowmetry. Baseline and maximal thermally stimulated skin blood flow (SkBF) responses were higher in forearms of trained subjects compared to untrained participants [baseline SkBF: 11 +/- 4 vs. 9 +/- 3 perfusion units (PU), p < 0.05; SkBF(max): 282 +/- 120 vs. 204 +/- 68 PU, p < 0.05]. Similarly, cutaneous vascular conductance (CVC) during local heating was superior in the forearm skin of trained versus untrained individuals (CVC(max): 3 +/- 1 vs. 2 +/- 1 PU mmHg(-1), p < 0.05). Peak hyperaemia following arterial occlusion and area under the reactive hyperaemia curve were also greater in forearm skin of the trained group (peak hyperaemia: 51 +/- 21 vs. 35 +/- 15 PU, p < 0.05; area under curve: 1596 +/- 739 vs. 962 +/- 796 PUs, p < 0.05). These results suggest that chronic exercise training in adolescents is associated with enhanced microvascular endothelial vasodilation in non-glabrous skin.

Recurrent non-specific low-back pain in adolescents: the role of exercise.

This study evaluated the efficacy of an exercise programme as an intervention for recurrent non-specific low-back pain (NLSBP) in adolescents. A randomized controlled trial was conducted with an experimental group (n = 27, age 14.6 years) who participated in an 8-week exercise programme and a matched control group (n = 27, age 14.6 years) who continued normal daily activities. All participants suffered from recurrent NSLBP. Pre and post intervention measures of NSLBP status (pain severity and consequences) and daily inactivity (time spent sitting, PC time, TV time) were reported in one week diaries. Two-way mixed ANOVA (independent variables: pre/post and experimental/control) was conducted for each dependent variable, significance was set at P < 0.05. Significant interaction effects were identified for the severity of pain, number of occasions missing sport due to NSLBP and amount of sport participated in. In each case the experimental group benefited from the exercise programme. In contrast, no significant interaction effects were observed for physical inactivity, both groups spent a similar amount of time sitting, watching TV and using a PC pre- and post- intervention. It was concluded that an exercise programme acted as an effective short-term treatment strategy for NSLBP in adolescents. Further evaluation is required to assess the long-term effectiveness.

Evaluation of the energy cost of playing a dance simulation video game in overweight and non-overweight children and adolescents.

The purpose of this study was to determine if there were any differences in the submaximal energy cost of movement between overweight (OW) and non-overweight (NO) children while playing a dance simulation video game, Dance Dance Revolution (DDR) and to determine if the cardiorespiratory measures obtained while playing the game met the American College of Sports Medicine (ACSM) recommendations for developing and maintaining cardiorespiratory fitness. Twenty-two children and adolescents (10 OW vs. 12 NO) participated in the study. Cardiorespiratory measurements were taken both during a maximal treadmill walking test and during a 12-minute Dance Dance Revolution protocol. The average absolute VO2 (OW: 917.1 +/- 257.1 vs. 590.6 +/- 147.9 mL . min (-1)) sustained over the DDR protocol was significantly higher in the OW group compared to the NO group. There was no significant difference in the average energy cost of movement when VO2 was normalized to fat-free mass (OW: 17.7 +/- 5.1 vs. NO: 17.3 +/- 3.9 mL . kgFFM (-1) . min (-1)). Both groups were above the minimal ACSM recommended heart rate intensity for developing and maintaining cardiorespiratory fitness when participating in the DDR protocol (OW: 64.83 % +/- 7.14 vs. NO: 64.51 % +/- 7.71), VO2 reserve, however, did not meet ACSM standards for developing and maintaining cardiorespiratory fitness.

Applicability of an allometric power equation to children, adolescents and young adults of extreme body size.

AIM: The aim of this study was to assess the applicability of a regression model for peak power (PP) and total mechanical work (TMW) for healthy children, adolescents and young adults especially in the extreme ranges of stature, mass, and body mass index (BMI). METHODS: A total of 454 children, adolescents and young adults aged 6-20 years volunteered for the study. Subjects, whose stature, mass and BMI were between the 10(th) and the 90(th) centile, were selected to calculate the prediction equation: 267 subjects fulfilled these criteria. Each subject performed two unilateral Wingate tests (ULWAnT), one with each leg. PP (Watts) and TMW (Joules) of the left and right leg were averaged for each individual. Ln(mass), in(stature), age, age(2), gender, and age x gender were used as predictors for in(PP) and ln(TMW). The applicability of the prediction equation was tested on individuals who were less than the 10(th) centile or greater than the 90(th) centile for stature, body mass and BMI. RESULTS: All independent variables were statistically significant (P<0.05) predictors of in(PP), adjusted R(2)=0.93 and all but gender were significant predictors for in(TMW), adjusted R(2)=0.95. However, measured in(PP) and in(TMW) were significantly lower than predicted in(PP) and in(TMW) for subjects >90th centile for stature, body mass, or BMI. CONCLUSIONS: the prediction equations overestimated PP and TMW in children, adolescents and young adults who were heavier than the reference subjects, as indicated by a relatively high body mass or high BMI for age or were taller than the reference subjects. The findings might reflect a deficit in anaerobic capacity in children, adolescents and young adults with relatively large body size for their age.

Interpretation and implementation of oxygen uptake kinetics studies in children with spastic cerebral palsy.

From the scant data available, it seems that children with CP have a low maximum Vo2, a high O2 cost of submaximal exercise, and inefficient gait mechanics characterized by high levels of co-contraction. Despite the non-steady-state nature of habitual activity, there seem to be no published data focusing on Vo2 kinetics in children with CP Before measuring Vo2 kinetics, the noise content of the data needs to be examined because this has important implications for estimating tau Vo2 values. On the basis of the preliminary findings presented here, the breath-by-breath Vo2 responses of children with CP seem to have a similar noise magnitude to those of typically developing children; however, because they have smaller response amplitudes, the averaging of several repeated trials will be even more important than in typically developing children. Thorough habituation will be required to enable participants to complete the simulated step change exercise protocols that will enable Vo2 kinetics to be quantified. To facilitate appropriate comparisons with control groups on the basis of relative exercise intensities, further work is needed to establish the efficacy of estimating T(Lac) from gas exchange data in children with CP. By measuring Vo2, kinetics in children with CP, it is hoped that we will not only gain valuable insights into their exercise intolerance, but we will also have an important tool for assessing the effects of interventions using submaximal, and therefore less strenuous, exercise.

Biological risk indicators for recurrent non-specific low back pain in adolescents.

OBJECTIVES: A matched case-control study was carried out to evaluate biological risk indicators for recurrent non-specific low back pain in adolescents. METHODS: Adolescents with recurrent non-specific low back pain (symptomatic; n = 28; mean (SD) age 14.9 (0.7) years) and matched controls (asymptomatic; n = 28; age 14.9 (0.7) years) with no history of non-specific low back pain participated. Measures of stature, mass, sitting height, sexual maturity (Tanner self assessment), lateral flexion of the spine, lumbar sagittal plane mobility (modified Schober), hip range of motion (Leighton flexometer), back and hamstring flexibility (sit and reach), and trunk muscle endurance (number of sit ups) were performed using standardised procedures with established reliability. Backward stepwise logistic regression analysis was performed, with the presence/absence of recurrent low back pain as the dependent variable and the biological measures as the independent variables. RESULTS: Hip range of motion, trunk muscle endurance, lumbar sagittal plane mobility, and lateral flexion of the spine were identified as significant risk indicators of recurrent low back pain (p<0.05). Follow up analysis indicated that symptomatic subjects had significantly reduced lateral flexion of the spine, lumbar sagittal plane mobility, and trunk muscle endurance (p<0.05). CONCLUSIONS: Hip range of motion, abdominal muscle endurance, lumbar flexibility, and lateral flexion of the spine were risk indicators for recurrent non-specific low back pain in a group of adolescents. These risk indicators identify the potential for exercise as a primary or secondary prevention method.

A school-based survey of recurrent non-specific low-back pain prevalence and consequences in children.

The aim of this investigation was to provide evidence of the prevalence and consequences of recurrent low-back pain in children from Northwest England. A cross-sectional survey was conducted involving a standardized questionnaire with established reliability and validity. A cross-sectional sample of 500 boys (n = 249) and girls (n = 251) aged between 10 and 16 years participated in the study. Average lifetime prevalence of low-back pain was 40.2% [95% confidence interval (CI) = 38.7-41.6]. Most cases of low-back pain were acute episodes that did not lead to disabling consequences. In contrast, 13.1% (95% CI = 12.5-13.7) experienced recurrent low-back pain that led to disabling consequences; 23.1% visited a medical practitioner, 30.8% experienced loss of physical activity/sports and 26.2% had been absent from school because of low-back pain. Recurrent low-back pain was particularly evident during late adolescence where one in five children were cases. The health education implications of low-back pain in children are discussed. It was concluded that low-back pain is a common complaint during childhood, although most cases are acute episodes that represent little health consequence. In contrast, some children experience recurrent low-back pain that can lead to disabling consequences. Future research should focus on recurrent low-back pain cases since they often led to disabling consequences.

Measurement error associated with spinal mobility measures in children with and without low-back pain.

AIM: Evidence of the reliability of measurements in children is scarce, particularly in children with low-back pain. The aim of this investigation was to evaluate the measurement error associated with repeated measures of spinal mobility measures in children with and without low-back pain by establishing 95% limits of agreement. METHODS: A repeated measures study was performed involving 119 children aged 11-16 y. Of this sample 30 subjects reported recurrent low-back pain and were classified as symptomatic, the remaining 89 subjects were asymptomatic. Standardized measures were taken, including the sit-and-reach test, hip range of motion (Leighton flexometer), lumbar flexibility (modified Schöber test) and lateral flexion of the spine. The same experimenter performed all testing, with 1 wk between the repeated measures. RESULTS: Correlation coefficients suggested that all measures exhibited good reliability in both the symptomatic (r = 0.80-0.95) and asymptomatic groups (r = 0.88-0.99). In contrast, the limits of agreement showed that all measures exhibited random error. The magnitude of random error was typically greater in the symptomatic subjects, suggesting that low-back pain may influence the reliability of typical measures used in this population. CONCLUSION: The magnitude of error must be interpreted in relation to analytical goals and the expected magnitude of change. In the authors' opinion the error presented appears acceptable for the serial monitoring of patients, although this will depend on the differences in mobility typically found.

Is there a physiologic basis for creatine use in children and adolescents?

The purported ergogenic benefits of creatine for the adult population have been well documented. In able-bodied children and adolescents, there is a paucity of data on creatine use and the purported ergogenic effects of creatine. Only 1 study to date has investigated the ergogenic properties of creatine in the adolescent population. The purpose of this review was to try to establish a rationale for creatine use in the child and adolescent population. The limited literature available in this area did not provide a strong enough rationale from either a physiologic or performance perspective for creatine supplementation in these populations. However, significantly more research is required before definitive conclusions can be made.

Fitness testing of pediatric liver transplant recipients.

Liver transplantation is accepted as the standard management for end-stage liver disease in children. Pediatric heart and heart-lung transplant recipients have shown significantly diminished exercise capacities compared with age-matched, able-bodied, control subjects. The primary aim of this study is to compare the fitness levels of a group of pediatric liver transplant (LT) recipients (LT group, 20 boys, 9 girls; age, 8.9 +/- 4.8 years; 56 +/- 35 months posttransplantation) with a group of able-bodied control subjects (22 boys, 12 girls; age, 8.4 +/- 3.8 years). The secondary aim is to compare the performance of the LT group against the Fitnessgram criterion standards. We assessed muscular endurance by means of a partial curl-up, flexibility by means of the back-saver sit and reach, and cardiorespiratory fitness by means of the progressive aerobic cardiovascular endurance run (PACER). The only significant (P <.05) difference between the 2 groups was the number of shuttles run in the PACER (control, 16.8 +/- 9.8 v LT, 11.5 +/- 8.4 shuttles). Other differences between the 2 groups were not significant. With regard to satisfying the Fitnessgram criterion standards, only 35% of the LT group achieved the standards for the partial curl-up, 88% of the LT group achieved the criterion standards for flexibility, and 0% achieved the standards for the PACER. These results indicate that the LT group has diminished exercise capacity. The origins of exercise limitations deserve further investigation.

Role of mechanical power estimates in the O2 cost of walking in children with cerebral palsy.

UNLABELLED: It has been established in able-bodied children that traditional biomechanical descriptors of gait such as stride length or stride frequency do not fully account for the differences seen in the energy cost of locomotion noted with age. Hence, measures of total body mechanical power output have been adopted to explain these differences. PURPOSE: The aim of this study was to estimate the ability of this mechanical power calculation to explain the variability in the metabolic energy cost of treadmill walking in children with spastic cerebral palsy (CP). METHODS: Thirteen subjects volunteered for the study. One group consisted of eight (6 male, 2 female) children with CP (age 12.2 +/- 2.7 yr). The second group consisted of five (4 male, 1 female) able-bodied controls (age 13.4 +/- 2.8 yr). The treadmill walking protocol consisted of one 4-min stage at 0% grade, 3 km x h(-1). Infrared markers were placed on 12 anatomical landmarks and data were collected using the OPTOTRAK motion analysis system over a 5-s time period during the last 30 s of the 4-min stage. On-line oxygen consumption VO2 measurements were obtained throughout using the Beckman Horizon Metabolic Cart. RESULTS: Relative VO2 (mL x kg(-1) x min(-1)) was significantly (P < 0.05) different between the two groups (CP: 16.6 +/- 6.5 vs control: 10.2 +/- 1.2). Simple linear regression analysis demonstrated that mechanical power measurements, incorporating transfers of energy between and within adjacent body segments, accounted for 87.2% of the total variability noted in VO2 for the children with CP, compared with only 2.4% in the able-bodied subjects. CONCLUSIONS: The results indicate that mechanical power differences explain the majority of the variability noted in VO2 in children with CP at a submaximal walking speed.

Co-activation of vastus lateralis and biceps femoris muscles in pubertal children and adults.

Determining the mechanisms of co-activation around the knee joint with respect to age and sex is important in terms of our greater understanding of strength development. The purpose of this study was to examine the effects of age, sex and muscle action on moment of force and electromyographic (EMG) activity of the agonist and antagonist muscle groups during isokinetic eccentric and concentric knee extension and flexion. The study comprised nine pubertal boys [mean age 12.6 (SD 0.5) years], nine girls [12.7 (SD 0.5) years] nine adult men [23.1 (SD 2.1) years] and nine adult women [23.7 (SD 3.1) years] who performed maximal isometric eccentric and concentric efforts of knee extensors and flexors on a dynamometer at 30 degrees x s(-1). The moment of force and surface EMG activity of vastus lateralis and biceps femoris muscles were recorded. The moment of force:agonist averaged EMG (aEMG) ratios were calculated. The antagonist aEMG values were expressed as a percentage of the aEMG activity of the same muscle, at the same angle, angular velocity and muscle action when the muscle was acting as agonist. Three-way analysis of variance (ANOVA) designs indicated no significant effects of age or sex on moment:aEMG ratios. Eccentric ratios were significantly higher than the corresponding concentric ones (P < 0.05). The results also indicated no significant effect of age and sex on the aEMG of the vastus lateralis and biceps femoris muscles when acting as antagonists. The antagonist aEMG was significantly greater during concentric agonist efforts compared with the corresponding eccentric ones (P < 0.05). These findings would suggest that the moment exerted per unit of agonist EMG and the antagonist activity are similar in children compared with adults and are not sex dependent. Future comparisons between eccentric and concentric moments of force and agonist ENG should take into consideration the antagonist effects, irrespective of age or sex.

Evaluation by exercise testing of the child with cerebral palsy.

Cerebral palsy (CP) is classified as a static encephalopathy. CP is a nonprogressive disorder affecting posture and movement and is commonly associated with a spectrum of developmental disabilities. Serial testing of physiological function can provide a quantitative assessment of improvement or decline in the condition of the patient. Furthermore, there are increasing numbers of children with disability who are involved in athletic activity, and the need for physiological feedback to the disabled athlete and coach is the same as for able-bodied individuals. It is acknowledged that children and adolescents with CP have a lower maximal oxygen consumption (VO2max) compared with their able-bodied peers. Children with CP also have distinctly subnormal values for peak anaerobic power and muscular endurance of the upper and lower limbs. Irrespective of the scaling method used (absolute or relative), when compared with normal data from healthy controls, children with CP scored between 2 and 4 standard deviations below the expected mean value for power. Gait abnormalities in children with CP have been shown to increase submaximal walking energy expenditure almost 3-fold compared with healthy children. Assessment of the metabolic cost alone is important but does not provide any information on the mechanisms giving rise to the high energy cost of locomotion in children with CP. Hence, a multidisciplinary (kinetic, kinematic and electromyographic) approach is an important noninvasive tool for studying some of the underlying mechanisms responsible for abnormal gait and elevated energy costs. A certain level of muscle co-contraction is necessary for achieving joint stability during locomotion, particularly at the ankle and knee. There appears, however, to be a co-contraction threshold beyond which there are associated elevated metabolic costs during locomotion in children with CP.

The cardiovascular responses of male subjects to kung fu techniques. Expert/novice paradigm.

BACKGROUND: The primary aim was to assess cardiovascular responses of expert and novice subjects to kung fu techniques. It was hypothesised that experienced subjects would demonstrate improved economy of movement during the techniques, evidenced by reduced exercise intensity. EXPERIMENTAL DESIGN: a comparative design was established utilising two groups; experienced (group E), and novice (group N). SETTING: the experimentation took place under laboratory conditions, but was designed to maximise external validity. PARTICIPANTS: the only preselection variables were regular attendance at training and experience. Nine experienced males (group E, exp 9.5 +/- 5.2 yrs) and nine novice males (group N, exp 1.2 +/- 0.1 yrs) participated. The only exclusion guidelines were contraindications to participate within a maximal test, no subjects were excluded upon this basis. INTERVENTIONS: N/A. MEASURES: each subject participated in three kung fu protocols (forms, kicking and punching). Each protocol, randomly allocated, consisted of ten work (30 sec) and ten rest periods (30 sec). MEASURES taken during the protocols were heart rate (HR) and oxygen consumption (VO2). These were expressed as a percentage of maximal values to reflect exercise intensity. RESULTS: During both the form protocol and punching protocol group E were found to be working at a significantly (p < 0.05) lower % VO2 max than group N (forms--group E = 71.5 +/- 5.3, group N = 82.1 +/- 6.1; punching--group E = 37.5 +/- 2.1, group N = 40.6 +/- 2.6, p < 0.05). This suggests that experienced subjects were more economical when performing similar movement patterns. CONCLUSIONS: It was concluded that cardiovascular responses to kung fu techniques differ depending upon experience level. It is difficult to directly relate this to improved economy since work output could not be accurately quantified. It was also found that kung fu protocols elicited exercise intensity into the cardiovascular training zone.

Role of cocontraction in the O2 cost of walking in children with cerebral palsy.

UNLABELLED: A major movement related limitation for children with spastic cerebral palsy (CP) is the compromised gait pattern, which may explain their excessive energy cost of locomotion. The aims of this study were to determine differences in the O2 cost of locomotion between children with CP (7 males, 2 females; 12.7 +/- 2.8 yr) and able-bodied controls (7 male, 1 female; 13.6 +/- 2.1 yr) and to assess the contribution that cocontraction of agonist and antagonist muscles had upon the elevated O2 cost seen in children with CP versus able-bodied controls. The treadmill submaximal walking protocol consisted of 2 x 4 min intermittent stages at 3 km.h-1 and 90% of the predetermined fastest walking speed (FWS) at 0% grade. Electromyographic data were collected during the final minute of each bout from vastus lateralis and hamstrings (thigh) and tibialis anterior and soleus (lower leg). Significant (P < 0.05) differences were noted at 3 km.h-1 for mass-relative VO2. (CP: 16.6 +/- 6.5 vs control: 10.2 +/- 1.2 ml.kg-1.min-1), % VO2max (CP: 53.5 +/- 26.0 vs CONTROL: 22.5 +/- 4.93) and heart rate (CP: 143 +/- 41 vs CONTROL: 91 +/- 14 beats.min-1). Thigh and lower leg muscle cocontraction accounted for 51.4% and 42.8%, respectively, of the variability in VO2 for the subjects with CP at 3 km.h-1. These results suggest that cocontraction is a major factor responsible for the higher energy cost of walking seen in children with CP.

Cocontraction and phasic activity during GAIT in children with cerebral palsy.

Simultaneous activity of agonist and antagonistic muscles during a task is known as cocontraction. The primary aim of the present study was to use a cocontraction index (CI) to quantify differences in EMG activity between a group of CP and control children at two different walking speeds. The secondary aim was to compare the amount of time the muscles were activated ("on" thresholds) between the groups. Seventeen subjects volunteered for the study. One group consisted of 9 (7M, 2F) children with CP (age 12.7 +/- 2.8 years, mean +/- SD). The second group consisted of 8 able-bodied controls (7M, 1F). The discontinuous submaximal treadmill walking protocol had two 4min stages at 0% gradient. Speeds selected were 3 km.h-1 and 90% of the pre-determined fastest walking speed (FWS). Two sites of CI were measured from the EMGs of tibialis anterior and soleus (leg) and vastus lateralis and hamstrings (thigh). Significantly (p < 0.05) higher CI values were noted for the CP subjects compared to the controls, irrespective of speed or cocontraction site and there was a significant (p < 0.05) increase in CI values with increased walking speed for both CP and control subjects. Phasic analyses for 5% max EMG and 10% max EMG "on" thresholds demonstrated significant (p < 0.05) main effects for group (CP subjects had a longer time period of muscle activation than controls) and speed (muscles were active longer at 90% FWS than 3 km.h-1). The precise mechanisms by which cocontraction contributes toward abnormal gait and wasted mechanical energy require further research incorporating both electromyographic and kinematic analysis.

Submaximal running economy in run-trained pre-pubertal boys.

There is an increasing tendency for young children to participate in training and competitive running. The impact long-term training has upon stimulating functional physiological adaptation has yet to be fully understood. In this study cardio-respiratory and kinematic differences were assessed at submaximal and maximal exercise intensities in run-trained and non-run-trained boys. Thirty three pre-pubertal boys volunteered to take part in the study. The subjects were in two groups: 15 run-trained subjects [age 11.7 +/- 1.06 yrs, mean +/- SD] and 18 non-run-trained (control) subjects [age 11.3 +/- 0.90 yrs]. Two separate (4 x 3 min) submaximal protocols were used for the trained and non-run-trained groups, with two of the speeds overlapping for comparison purposes. In addition, all boys also performed a maximal oxygen consumption test. Mean VO2max value for the run trained group was 60.5 +/- 3.3 ml/kg/min and for the control group 51.1 +/- 4.3 ml/kg/min, (p < 0.001). No significant differences were found for submaximal running economy at either comparison speed. In addition, no significant (p > 0.05) differences were noted between the groups for any of the kinematic variables at the two comparison speeds. However, selected physiological differences did exist at the submaximal running speeds. The source of the differences that did exist between the two groups may be the result of training, genetic pre-selection or developmental differences between the groups.