Fatigue in children and adolescents after burns: evaluating the problem using longitudinal data.

PURPOSE: Describe prevalence and severity of fatigue in children and adolescents with burns during six months after hospital discharge, identify potential explanatory variables, and examine the relationship with exercise capacity. MATERIALS AND METHODS: Fatigue was assessed using the Pediatric-Quality-of-Life-Inventory-Multidimensional-Fatigue-Scale (PedsQL-MFS) at discharge, and six weeks, three-, and six months after discharge. PedsQL-MFS scores ≥1 SD below the age-group specific non-burned reference mean were considered to signify fatigue. RESULTS: Twenty-two children and adolescents (13 boys/9 girls, age 6-18 years, with burns covering 2-34% of total body surface area) were included. The prevalence of fatigue decreased from 65% (11/17) at discharge to 28% (5/18) six months after discharge. At group level, fatigue severity decreased over time, reaching healthy reference values from six weeks after discharge and beyond. At individual level, the course of fatigue severity varied widely. Fatigue severity at six months after discharge could not be predicted by age, sex, or burn severity (p = 0.51, p = 0.58, p = 0.95, respectively). The association with exercise capacity was weak (r = 0.062-0.538). CONCLUSIONS: More than a quarter of pediatric burn patients reported fatigue six months after discharge. Further research in larger populations is required, including also the impact of burn-related fatigue on daily functioning and quality of life.Trial registration number: OND1353942Implications for rehabilitationFatigue should be recognized as a potential consequence of (pediatric) burns, even several months post burnFatigue should be assessed regularly after discharge in all children and adolescents with burns, as it seems not possible to predict its severity from age, sex, or burn severity characteristicsThe weak association between exercise capacity and self-reported fatigue suggests that burn-related fatigue is not simply a consequence of a reduced exercise capacity.

Magnetic Resonance-Compatible Arm-Crank Ergometry: A New Platform Linking Whole-Body Calorimetry to Upper-Extremity Biomechanics and Arm Muscle Metabolism.

INTRODUCTION: Evaluation of the effect of human upper-body training regimens may benefit from knowledge of local energy expenditure in arm muscles. To that end, we developed a novel arm-crank ergometry platform for use in a clinical magnetic resonance (MR) scanner with 31P spectroscopy capability to study arm muscle energetics. Complementary datasets on heart-rate, whole-body oxygen consumption, proximal arm-muscle electrical activity and power output, were obtained in a mock-up scanner. The utility of the platform was tested by a preliminary study over 4 weeks of skill practice on the efficiency of execution of a dynamic arm-cranking task in healthy subjects. RESULTS: The new platform successfully recorded the first ever in vivo 31P MR spectra from the human biceps brachii (BB) muscle during dynamic exercise in five healthy subjects. Changes in BB energy- and pH balance varied considerably between individuals. Surface electromyography and mechanical force recordings revealed that individuals employed different arm muscle recruitment strategies, using either predominantly elbow flexor muscles (pull strategy; two subjects), elbow extensor muscles (push strategy; one subject) or a combination of both (two subjects). The magnitude of observed changes in BB energy- and pH balance during ACT execution correlated closely with each strategy. Skill practice improved muscle coordination but did not alter individual strategies. Mechanical efficiency on group level seemed to increase as a result of practice, but the outcomes generated by the new platform showed the additional caution necessary for the interpretation that total energy cost was actually reduced at the same workload. CONCLUSION: The presented platform integrates dynamic in vivo 31P MRS recordings from proximal arm muscles with whole-body calorimetry, surface electromyography and biomechanical measurements. This new methodology enables evaluation of cyclic motor performance and outcomes of upper-body training regimens in healthy novices. It may be equally useful for investigations of exercise physiology in lower-limb impaired athletes and wheelchair users as well as frail patients including patients with debilitating muscle disease and the elderly.

Questionnaires to Assess Facilitators and Barriers of Early Mobilization in Critically Ill Patients; Which One to Choose? A Systematic Review.

Implementing and performing early mobilization is a complex process requiring multidisciplinary input and cooperation. To gain insight in its facilitators and barriers, various surveys have been developed. A systematic review was conducted, to identify the psychometric properties, feasibility and suitability of questionnaires to assess facilitators and barriers of early mobilization in critically ill patients. Data were extracted regarding a.o. definition of early mobilization, development, psychometric properties, content and themes, question format. The search identified 537 publications of which 13 unique questionnaires were included. The questionnaires showed wide variation in extensiveness of development. Only six questionnaires actually assessed validity and reliability. Which questionnaire to choose depends on the aim of its use, required level of detail and specifics of the ICU, though three questionnaires were recommended as their definition of early mobilization covered a broad range of activities, including nursing related mobility activities. International consensus on what constitutes early mobilization is desirable.

Predictability of exercise capacity following pediatric burns: a preliminary investigation.

PURPOSE: Describe the course of exercise capacity in pediatric burn patients during the initial 6 months after hospital discharge, and examine whether its recovery can be predicted from burn characteristics, sociodemographic characteristics, and/or prior assessment. MATERIALS AND METHODS: Exercise capacity was assessed at discharge, and 6 weeks, 3 months, and 6 months after discharge using the Steep Ramp Test (SRT). RESULTS: Twenty-four pediatric patients with burns affecting 0.1-34% of total body surface area were included. At group level, exercise capacity was low at discharge and did not reach healthy reference values within 6 months, despite significant improvement over time. At individual level, the course of exercise capacity varied widely. Six months after discharge, 48% of participants scored more than one standard deviation below healthy age- and sex-specific reference values. SRT outcomes at 6 weeks and 3 months were the best predictors of exercise capacity 6 months after discharge, explaining, respectively, 76% and 93% of variance. CONCLUSIONS: Forty-eight percent of participants did not achieve healthy reference values of exercise capacity and were therefore considered "at risk" for diminished functioning. Our preliminary conclusion that early assessment of exercise capacity with the SRT can timely identify those patients, needs to be strengthened by further research.IMPLICATIONS FOR REHABILITATIONPediatric burns can be considered as a chronic medical condition because of the lifelong consequences.Exercise capacity is reduced following- even minor -pediatric burns.Recovery patterns vary widely: some pediatric burn patients achieve healthy levels of exercise capacity without specific intervention, while others do not.The Steep Ramp Test can be used to assess exercise capacity, identifying those "at risk" for adverse outcomes at an early stage.Patients "at risk" should be encouraged to play sports and adopt an active lifestyle.

Synergies reciprocally relate end-effector and joint-angles in rhythmic pointing movements.

During rhythmic pointing movements, degrees of freedom (DOF) in the human action system-such as joint-angles in the arm-are assumed to covary to stabilise end-effector movement, e.g. index finger. In this paper, it is suggested that the end-effector movement and the coordination of DOF are reciprocally related in synergies that link DOF so as to produce the end-effector movement. The coordination of DOF in synergies and the relation between end-effector movement and DOF coordination received little attention, though essential to understand the principles of synergy formation. Therefore, the current study assessed how the end-effector movement related to the coordination of joint-angles during rhythmic pointing across target widths and distances. Results demonstrated that joint-angles were linked in different synergies when end-effector movements differed across conditions. Furthermore, in every condition, three joint-angles (shoulder plane of elevation, shoulder inward-outward rotation, elbow flexion-extension) largely drove the end-effector, and all joint-angles contributed to covariation that stabilised the end-effector. Together, results demonstrated synergies that produced the end-effector movement, constrained joint-angles so that they covaried to stabilise the end-effector, and differed when end-effector movement differed. Hence, end-effector and joint-angles were reciprocally related in synergies-indicating that the action system was organised as a complex dynamical system.

Course of prevalence of scar contractures limiting function: A preliminary study in children and adolescents after burns.

BACKGROUND: Scar contracture is a well-known sequela of burns that is specifically relevant as it may limit function. Reports regarding the course of scar contractures, however, are scarce and, moreover, not focussed on function. This study describes the course of prevalence of scar contractures that limit function in children and adolescents after burns. METHOD: Range of motion (ROM) of extremity joints of 20 children and adolescents after burns were assessed at discharge (T0) and at six weeks (T1), three months (T2), and six months (T3) after discharge. A scar contracture limiting function was defined as a measured ROM lower than the functional ROM, i.e., ROM used to perform daily activities by unimpaired subjects. RESULTS: At discharge (T0), 89.5% of the subjects had one or more scar contractures that limited function. Six months later (T3), this prevalence was 76.5%. At discharge (T0), less function limiting scar contractures were found for the upper extremity (29.7%) than the lower extremity (53.3%). Over time, prevalence of contractures in both extremities fluctuated between 22% and 35%. CONCLUSIONS: The majority of children and adolescents (13/17) still had scar contractures limiting function six months after discharge (T3). Substantial longitudinal studies over a longer period of time are needed to increase our knowledge on the course of these scar contractures in order to support improvements in burn care. TRIAL REGISTRATION: The study is approved by the Regional Committee for Patient-Oriented Research Leeuwarden in the Netherlands (NL45917.099.13).

Fixed muscle synergies and their potential to improve the intuitive control of myoelectric assistive technology for upper extremities.

BACKGROUND: Users of myoelectric controlled assistive technology (AT) for upper extremities experience difficulties in controlling this technology in daily life, partly because the control is non-intuitive. Making the control of myoelectric AT intuitive may resolve the experienced difficulties. The present paper was inspired by the suggestion that intuitive control may be achieved if the control of myoelectric AT is based on neuromotor control principles. A significant approach within neurocomputational motor control suggests that myosignals are produced via a limited number of fixed muscle synergies. To effectively employ this approach in myoelectric AT, it is required that a limited number of muscle synergies is systematically exploited, also when muscles are used differently as required in controlling myoelectric AT. Therefore, the present study examined the systematic exploitation of muscle synergies when muscles were used differently to complete point-to-point movements with and without a rod. METHODS: Healthy participants made multidirectional point-to-point movements with different end-effectors, i.e. with the index finger and with rods of different lengths. Myosignals were collected from 22 muscles in the arm, trunk, and back, and subsequently partitioned into muscle synergies per end-effector and for a pooled dataset including all end-effectors. The exploitation of these muscle synergies was assessed by evaluating the similarity of structure and explanatory ability of myosignals of per end-effector muscle synergies and the contribution of pooled muscle synergies across end-effectors. RESULTS: Per end-effector, 3-5 muscle synergies could explain 73.8-81.1% of myosignal variation, whereas 6-8 muscle synergies from the pooled dataset also captured this amount of myosignal variation. Subsequent analyses showed that gradually different muscle synergies-extracted from separate end-effectors-were exploited across end-effectors. In line with this result, the order of contribution of muscle synergies extracted from the pooled dataset gradually reversed across end-effectors. CONCLUSION: A limited number of muscle synergies was systematically exploited in the examined set of movements, indicating a potential for the fixed muscle synergy approach to improve the intuitive control of myoelectric AT. Given the gradual change in muscle synergy exploitation across end-effectors, future research should examine whether this potential can be extended to a larger range of movements and tasks.

Rating scales for shoulder and elbow range of motion impairment: Call for a functional approach.

BACKGROUND: To evaluate the effect of (new) treatments or analyse prevalence and risk factors of contractures, rating scales are used based on joint range of motion. However, cut-off points for levels of severity vary between scales, and it seems unclear how cut-off points relate to function. The purpose of this study was to compare severity ratings of different rating scales for the shoulder and elbow and relate these with functional range of motion. METHODS: Often used contracture severity rating scales in orthopedics, physiotherapy, and burns were included. Functional range of motion angles for the shoulder and elbow were derived from a recent synthesis published by our group. Shoulder flexion and elbow flexion range of motion data of patients three months after a burn injury were rated with each of the scales to illustrate the effects of differences in classifications. Secondly, the shoulder and elbow flexion range of motion angles were related to the required angles to perform over 50 different activities of daily living tasks. RESULTS: Eighteen rating scales were included (shoulder: 6, elbow: 12). Large differences in the number of severity levels and the cut-off points between scales were determined. Rating the measured range of motions with the different scales showed substantial inconsistency in the number of joints without impairment (shoulder: 14-36%, elbow: 26-100%) or with severe impairment (shoulder: < 10%-29%, elbow 0%-17%). Cut-off points of most scales were not related to actual function in daily living. CONCLUSION: There is an urgent need for rating scales that express the severity of contractures in terms of loss of functionality. This study proposes a direction for a solution.

Variability in coordination patterns in children with developmental coordination disorder (DCD).

High motor variability is an often-found characteristic of Developmental Coordination Disorder (DCD). Still, the role of high motor variability in DCD needs further examination. This study focused on variability in coordination patterns, which is essential considering that DCD is a coordination disorder. We examined variability in coordination patterns of the arm over repetitions of trials in goal-directed reaching movements. This variability was partitioned into variability that does not affect the index fingertip position (Vucm) and variability that does affect the index fingertip position (Vort). This study aimed to increase the understanding of motor variability in DCD by comparing Vucm and Vort between children with DCD and typically developing (TD) children in a goal-directed reaching task. Twenty-two children (eleven with DCD) ages 6-11 performed 30 reaching movements. The Uncontrolled Manifold method was used to quantify Vucm and Vort. Results showed that children with DCD had more Vucm than TD children while Vort was similar between groups, showing that coordination patterns in children with DCD are more variable, but interestingly, this higher variability does not affect performance. This study indicates that high motor variability in DCD is not necessarily negative. Possible roles of motor variability in DCD are discussed.

Development of reaching during mid-childhood from a Developmental Systems perspective.

Inspired by the Developmental Systems perspective, we studied the development of reaching during mid-childhood (5-10 years of age) not just at the performance level (i.e., endpoint movements), as commonly done in earlier studies, but also at the joint angle level. Because the endpoint position (i.e., the tip of the index finger) at the reaching target can be achieved with multiple joint angle combinations, we partitioned variability in joint angles over trials into variability that does not (goal-equivalent variability, GEV) and that does (non-goal-equivalent variability, NGEV) influence the endpoint position, using the Uncontrolled Manifold method. Quantifying this structure in joint angle variability allowed us to examine whether and how spatial variability of the endpoint at the reaching target is related to variability in joint angles and how this changes over development. 6-, 8- and 10-year-old children and young adults performed reaching movements to a target with the index finger. Polynomial trend analysis revealed a linear and a quadratic decreasing trend for the variable error. Linear decreasing and cubic trends were found for joint angle standard deviations at movement end. GEV and NGEV decreased gradually with age, but interestingly, the decrease of GEV was steeper than the decrease of NGEV, showing that the different parts of the joint angle variability changed differently over age. We interpreted these changes in the structure of variability as indicating changes over age in exploration for synergies (a family of task solutions), a concept that links the performance level with the joint angle level. Our results suggest changes in the search for synergies during mid-childhood development.

Physical activity and sedentary behavior following pediatric burns - a preliminary investigation using objective activity monitoring.

BACKGROUND: Adequate levels of regular physical activity (PA) are crucial for health and well-being. Pediatric burn injuries can have major physiological consequences in both the short and long term. The question is whether these consequences affect post burn PA levels. This study therefore aimed to describe PA and sedentary behavior (SB) in children and adolescents 1-5 years after burn injury. METHODS: Daily PA and SB were monitored in 20 children and adolescents (12 boys and 8 girls, aged 6-17 years, with burns covering 10-37% of total body surface area, 1-5 years post burn) for 1 week using the ActiGraph GTX3+ accelerometer. Activity counts were categorized into SB, light PA, moderate PA, vigorous PA, moderate-to-vigorous PA (MVPA), and total PA. Outcomes were compared with non-burned reference values and PA levels recommended by the World Health Organization (WHO). RESULTS: The participants spent about 5.1 h per day on total PA and 7.4 h on SB. Most of the active time (~ 83%) was categorized as light PA. Thirty-five percent of the group, especially the young boys, spent on average ≥ 60 min on MVPA per day. The boys, although with large interindividual differences, spent more time on MVPA than the girls (p < .005). Older age was associated with less PA time, while more time was spent sedentary. No trends were found indicating an effect of burn characteristics, time post burn, or length of hospital stay, and no differences were found with non-burned peers. CONCLUSION: Duration and intensity of PA and SB in children and adolescents 1-5 years after burn injury were similar to non-burned peers. However, only 35% of the group met the WHO physical activity recommendation. Given the increased long term risk for physical conditions following pediatric burns, physical activity should be encouraged in this vulnerable population. TRIAL REGISTRATION: The study is registered in the National Academic Research and Collaborations Information System of the Netherlands (OND1348800).

What the Dynamic Systems Approach Can Offer for Understanding Development: An Example of Mid-childhood Reaching.

The Dynamic Systems Approach (DSA) to development has been shown to be a promising theory to understand developmental changes. In this perspective, we use the example of mid-childhood (6- to 10-years of age) reaching to show how using the DSA can advance the understanding of development. Mid-childhood is an important developmental period that has often been overshadowed by the focus on the acquisition of reaching during infancy. This underrepresentation of mid-childhood studies is unjustified, as earlier studies showed that important developmental changes in mid-childhood reaching occur that refine the skill of reaching. We review these studies here for the first time and show that different studies revealed different developmental trends, such as non-monotonic and linear trends, for variables such as movement time and accuracy at target. Unfortunately, proposed explanations for these developmental changes have been tailored to individual studies, limiting their scope. Also, explanations were focused on a single component or process in the system that supposedly causes developmental changes. Here, we propose that the DSA can offer an overarching explanation for developmental changes in this research field. According to the DSA, motor behavior emerges from interactions of multiple components entailed by the person, environment, and task. Changes in all these components can potentially contribute to the emerging behavior. We show how the principles of change of the DSA can be used as an overarching framework by applying these principles not only to development, but also the behavior itself. This underlines its applicability to other fields of development.

Does practicing a wide range of joint angle configurations lead to higher flexibility in a manual obstacle-avoidance target-pointing task?

Flexibility in motor actions can be defined as variability in the use of degrees of freedom (e.g., joint angles in the arm) over repetitions while keeping performance (e.g., fingertip position) stabilized. We examined whether flexibility can be increased through enlarging the joint angle range during practice in a manual obstacle-avoidance target-pointing task. To establish differences in flexibility we partitioned the variability in joint angles over repetitions in variability within (GEV) and variability outside the solution space (NGEV). More GEV than NGEV reflects flexibility; when the ratio of the GEV and NGEV is higher, flexibility is higher. The pretest and posttest consisted of 30 repetitions of manual pointing to a target while moving over a 10 cm high obstacle. To enlarge the joint angle range during practice participants performed 600 target-pointing movements while moving over obstacles of different heights (5-9 cm, 11-15 cm). The results indicated that practicing movements over obstacles of different heights led participants to use enlarged range of joint angles compared to the range of joint angles used in movements over the 10 cm obstacle in the pretest. However, for each individual obstacle neither joint angle variance nor flexibility were higher during practice. We also did not find more flexibility after practice. In the posttest, joint angle variance was in fact smaller than before practice, primarily in GEV. The potential influences of learning effects and the task used that could underlie the results obtained are discussed. We conclude that with this specific type of practice in this specific task, enlarging the range of joint angles does not lead to more flexibility.

Perceived fatigue following pediatric burns.

PURPOSE: Fatigue is a common consequence of numerous pediatric health conditions. In adult burn survivors, fatigue was found to be a major problem. The current cross-sectional study is aimed at determining the levels of perceived fatigue in pediatric burn survivors. METHODS: Perceived fatigue was assessed in 23 children and adolescents (15 boys and 8 girls, aged 6-18 years, with burns covering 10-46% of the total body surface area, 1-5 years post burn) using both child self- and parent proxy reports of the Pediatric Quality of Life Inventory Multidimensional Fatigue Scale. Outcomes were compared with reference values of non-burned peers. RESULTS: At group level, pediatric burn survivors did not report significantly more symptoms of fatigue than their non-burned peers. Individual assessments showed, however, that four children experienced substantial symptoms of fatigue according to the child self-reports, compared to ten children according to the parent proxy reports. Furthermore, parents reported significantly more symptoms of fatigue than the children themselves. Age, gender, extent of burn, length of hospital stay, and number of surgeries could not predict the level of perceived fatigue post-burn. CONCLUSIONS: Our results suggest that fatigue is prevalent in at least part of the pediatric burn population after 1-5 years. However, the fact that parents reported significantly more symptoms of fatigue then the children themselves, hampers evident conclusions. It is essential for clinicians and therapists to consider both perspectives when evaluating pediatric fatigue after burn and to determine who needs special attention, the pediatric burn patient or its parent.

Prevalence of scar contractures after burn: A systematic review.

OBJECTIVE: Burn scar contractures are the pathological outcome of excessive scarring and ongoing scar contraction. Impairment of joint range of motion is a threat to performing activities in daily living. To direct treatment strategies to prevent and/or correct such contractures, insight into the prevalence, course, and determinants is essential. METHODS: A literature search was conducted including Pubmed, Cochrane library, CINAHL, and PEDro. Articles were included if they provided burn scar contracture data to calculate the point prevalence. The quality of the articles was scored. Data were extracted regarding study, subject and burn characteristics, method of scar contracture assessment, point prevalence, and possible determinants. RESULTS: Nine articles and one abstract could be included for data extraction. The prevalence at discharge was 38-54%, but with a longer time after burn, the prevalence was lower. Contractures were more likely to occur in more severe burns, flame burns, children, female, the cervical spine, and the upper extremity. CONCLUSIONS: The prevalence of burn scar contractures varies considerably between studies. When prevalence is unclear, it is also difficult to investigate potential determinants and evaluate changes in interventions. There is a need for extensive, well-designed longitudinal (inter)national studies that investigate prevalence of scar contractures, their evolvement over time, and risk factors.

Joint-Angle Coordination Patterns Ensure Stabilization of a Body-Plus-Tool System in Point-to-Point Movements with a Rod.

When performing a goal-directed action with a tool, it is generally assumed that the point of control of the action system is displaced from the hand to the tool, implying that body and tool function as one system. Studies of how actions with tools are performed have been limited to studying either end-effector kinematics or joint-angle coordination patterns. Because joint-angle coordination patterns affect end-effector kinematics, the current study examined them together, with the aim of revealing how body and tool function as one system. Seated participants made point-to-point movements with their index finger, and with rods of 10, 20, and 30 cm attached to their index finger. Start point and target were presented on a table in front of them, and in half of the conditions a participant displacement compensated for rod length. Results revealed that the kinematics of the rod's tip showed higher peak velocity, longer deceleration time, and more curvature with longer rods. End-effector movements were more curved in the horizontal plane when participants were not displaced. Joint-angle trajectories were similar across rod lengths when participants were displaced, whereas more extreme joint-angles were used with longer rods when participants were not displaced. Furthermore, in every condition the end-effector was stabilized to a similar extent; both variability in joint-angle coordination patterns that affected end-effector position and variability that did not affect end-effector position increased in a similar way vis-à-vis rod length. Moreover, the increase was higher in those conditions, in which participants were not displaced. This suggests that during tool use, body and tool are united in a single system so as to stabilize the end-effector kinematics in a similar way that is independent of tool length. In addition, the properties of the actual trajectory of the end-effector, as well as the actual joint-angles used, depend on the length of the tool and the specifics of the task.

Fatigue in patients with juvenile idiopathic arthritis: A systematic review of the literature.

OBJECTIVE: To perform a systematic review of the current literature on studies related to fatigue in children with JIA. We studied the measurements that were used to assess fatigue and we focused on three outcome measurements, namely, (1) the prevalence of fatigue in JIA patients, (2) the determinants of and associations with fatigue in JIA patients, and (3) the impact of fatigue in JIA patients on daily life. METHODS: A search was conducted in the electronic databases Pubmed and Embase from January 1, 2000 until August 27, 2015. The quality in prognostic factors (QUIPS) tool was used to assess the risk of bias (ROB) in the selected studies, focused on the outcome fatigue. Of all, two authors independently judged the ROB. RESULTS: A total of 15 studies were included in this review. To assess fatigue, two unidimensional and three multidimensional scales were used, which hampered comparison. Fatigue was reported to be present in 60-76% of the patients with JIA and was related to time of day, disease activity, pain, psychosocial factors, and sleep. Minor consequences for daily life were found, though this was not studied extensively. CONCLUSION: Fatigue is common in patients with JIA. The cause reflects a complex interplay of different factors. Based on results from this review and its body of knowledge, a conceptual model for fatigue in patients with JIA is proposed. Consensus is needed for future studies on how to assess fatigue. We promote the use of a combination of unidimensional and validated multidimensional measurements.

Anthropometry, muscular strength and aerobic capacity up to 5 years after pediatric burns.

OBJECTIVE: Physical functioning is of major importance after burns in many areas of life, in both the short and the long term. This cross-sectional study aimed to describe anthropometry, muscular strength and aerobic capacity in children and adolescents between 0.5-5 years after burns over 10% TBSA. PROCEDURES: Assessments took place in a mobile exercise lab. Demographics, burn characteristics and anthropometrics were recorded. Muscular strength in six muscle groups was measured using hand-held dynamometry and aerobic capacity was measured with a graded cardiopulmonary exercise test. Subjects' scores were compared with Dutch age- and gender-matched norm values and converted to Z-scores. RESULTS: The assessments were completed by 24 subjects with pediatric burns ranging from 10 to 41% TBSA and time after burn from 1 to 5 years (58.3% male; 6-18 years). On group level, no significant differences between the subjects' scores and norm values were found. No trends were seen indicating an effect of extent of burn or time after burn. Individually, eight subjects (33.3%), mostly aged 6 or 7, showed significantly low performance on at least one variable: seven for strength, one for aerobic capacity and one for both. CONCLUSION: Anthropometry, muscular strength and aerobic capacity are adequate in the majority of Dutch children and adolescents 1-5 years after 10-41% TBSA burns.

Individual differences in learning a novel discrete motor task.

Many motor learning studies focus on average performance while it is known from everyday life experience that humans differ in their way of learning new motor tasks. This study emphasises the importance of recognizing individual differences in motor learning. We studied individual tool grasping profiles of individuals who learned to pick up objects with a novel tool, a pair of pliers. The pair of pliers was attached to the thumb and the index finger so that the tip of the thumb and the tip of the index finger were displaced to the beaks of the pair of pliers. The grasp component was manipulated by varying the location of the hinge of the pair of pliers, which resulted in different relations between beak opening and closing and finger opening and closing. The Wider Beak group had the hinge at 7 cm, the Same Beak group had the hinge at 10 cm (i.e., in the middle), and the Smaller Beak group had the hinge at 13 cm from the digits. Each group consisted of ten right-handed participants who picked up an object with one of the pairs of pliers 200 times on two subsequent days. Hand opening, plateau phase, hand closing, grasping time and maximum aperture were analyzed. To characterize individual changes over practice time, a log function was fitted on these dependent variables and the ratio of improvement was determined. Results showed that at the beginning stage of tool use learning the characteristic grasping profile consisted of three phases; hand opening, plateau phase and hand closing. Over practicing individual participants differed in the number of phases that changed, the amount of change in a phase and/or the direction of change. Moreover, with different pliers different learning paths were found. The importance of recognizing individual differences in motor learning is discussed.