Digital technologies for motor rehabilitation in children: protocol for a cross-sectional European survey.

INTRODUCTION: Digital technologies can be used as part of paediatric motor rehabilitation to remediate impairment, promote recovery and improve function. However, the uptake of digital technologies in this clinical field may be limited.The aim of this study is to describe and explain digital technology use for paediatric motor rehabilitation. The specific objectives will be: (1) to describe the access to, acceptance of and use of digital technologies as a function of individual factors related to professionals practicing motor rehabilitation with children, and of environmental factors related to paediatric rehabilitation practice and (2) to explain digital technology use with a causal model based on the 'unified theory of acceptance and use of technology'. METHODS AND ANALYSIS: RehaTech4child (Rehabilitation Technologies For children) is a cross-sectional study involving an online survey, that is sponsored by the European Academy of Childhood Disability (EACD). The survey protocol follows the Strengthening the Reporting of Observational Studies in Epidemiology and CHERRIES (Checklist for Reporting Results of Internet E-Surveys) guidelines. The survey includes 43 questions about (1) respondents' individual and environmental characteristics; (2) the ease of access to digital technologies, and the frequency, type and purpose of use of those technologies and (3) acceptance of technologies and barriers to their use. The survey is intended for professionals involved in paediatric motor rehabilitation. It is disseminated across Europe by the EACD network in 20 languages. Participation is anonymous and voluntary. We aim to include 500 respondents to ensure sufficient precision for the description of study outcomes and to perform stratified analyses by the main determinants. ETHICS AND DISSEMINATION: Ethics approval was waived by the Brest CHRU Institutional Review Board. The study is conducted according to current French legislation (loi Jardé (n°2012-300)) and the survey is GDPR compliant. Study findings will be presented at national and international meetings and submitted for publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT05176522.

Effectiveness of wheeled mobility skill interventions in children and young people with cerebral palsy: A systematic review.

AIM: To systematically review the effectiveness of wheeled mobility interventions in children and young people with cerebral palsy (CP). METHOD: A systematic literature search was performed in MEDLINE, Embase, Cochrane Central Register of Controlled Trials, EBSCO, PEDro, and Web of Science using database-specific concepts such as 'child' and 'wheelchair'. Studies focusing on wheeled mobility skill interventions with participants aged 6 to 21 years with CP were included. RESULTS: Twenty studies with 203 participants were included. The impact of wheeled mobility skill interventions was assessed on mobility skills (n = 18), activity and participation (n = 10), and quality of life (n = 3). No studies reported effects on stress, fatigue, and motivational aspects. Interventions included power wheelchair skill training (n = 12), computer-based training (n = 5), smart wheelchair training (n = 2), and manual wheelchair training (n = 1), showing positive wheeled mobility intervention effects. Study quality based on the Methodological Index for Non-Randomized Studies scale was 9 out of 16 and 14 out of 24 for non-comparative and comparative studies respectively. Risk of bias was serious-to-critical on the Risk of Bias in Non-Randomized Studies of Interventions. INTERPRETATION: Wheeled mobility interventions showed promising beneficial effects on wheeled mobility, activity and participation, and quality of life for children and young people with CP. Future studies with structured and standardized training programmes and assessment tools are warranted to further accelerate the wheeled mobility skill acquisition process in this population. WHAT THIS PAPER ADDS: Wheeled mobility interventions improve wheeled mobility skills in individuals with cerebral palsy. The mobility skill acquisition process benefits from structured and standardized training. Knowledge of the intervention effects on participation and quality of life is limited. Most studies had moderate quality of evidence because of methodological limitations.

Teleintervention for users of augmentative and alternative communication devices: A systematic review.

AIM: To synthesize existing evidence on the effectiveness of speech-language teleinterventions delivered via videoconferencing to users of augmentative and alternative communication (AAC) devices. METHOD: A systematic literature search was conducted in 10 electronic databases, from inception until August 2021. Included were speech-language teleinterventions delivered by researchers and/or clinicians via videoconferencing to users of AAC devices, without restrictions on chronological age and clinical diagnosis. The quality of the studies included in the review was appraised using the Downs and Black checklist and the Single-Case Experimental Design Scale; risk of bias was assessed using the Risk Of Bias In Non-Randomized Studies - of Interventions and the single-case design risk of bias tools. RESULTS: Six teleinterventions including 25 participants with a variety of conditions, such as Down syndrome, autism, Rett syndrome, and amyotrophic lateral sclerosis met the inclusion criteria. Five studies used a single-case experimental design and one was a cohort study. Teleinterventions included active consultation (n = 2), functional communication training (n = 2), brain-computer interface (n = 1), and both teleintervention and in-person intervention (n = 1). All teleinterventions reported an increase in participants' independent use of AAC devices during the training sessions compared to baseline, as well as an overall high satisfaction and treatment acceptability. INTERPRETATION: Speech-language teleinterventions for users of AAC devices show great potential for a successful method of service delivery. Future telehealth studies with larger sample sizes and more robust methodology are strongly encouraged to allow the generalization of results across different populations. WHAT THIS PAPER ADDS: Individuals can learn to use augmentative and alternative communication (AAC) devices independently during tele-AAC interventions. Service providers and recipients reported an overall high satisfaction and acceptability for AAC services delivered via teleinterventions. Speech-language teleinterventions may be an effective method of providing AAC intervention services.

Psychometric properties of upper limb kinematics during functional tasks in children and adolescents with dyskinetic cerebral palsy.

Dyskinetic cerebral palsy (DCP) is characterised by involuntary movements, and the movement patterns of children with DCP have not been extensively studied during upper limb tasks. The aim of this study is to evaluate psychometric properties of upper limb kinematics in participants with DCP and typically developing (TD) participants. In current repeatability and validity study, forty individuals with typical development (n = 20) and DCP (n = 20) performed a reach forward/sideways and a reach and grasp task during motion analysis on two occasions. Joint angles at point of task achievement (PTA) and spatio-temporal parameters were evaluated within-and between-sessions using intra-class correlation coefficients (ICC) and standard error of measurement (SEM). Independent t-tests/Mann-Whitney-U tests were used to compare parameters between groups. Within-session ICC values ranged from 0.45 to 1.0 for all parameters for both groups. Within-session SEM values ranged from 1.1° to 11.7° for TD participants and from 1.9° to 13.0° for participants with DCP. Eight within-session repetitions resulted in the smallest change in ICC and SEM values for both groups. Within-session variability was higher for participants with DCP in comparison with the TD group for the majority of the joint angles and spatio-temporal parameters. Intrinsic variability over time was small for all angles and spatio-temporal parameters, whereas extrinsic variability was higher for elbow and scapula angles. Between-group differences revealed lower shoulder adduction and higher elbow flexion, pronation and wrist flexion, as well as higher trajectory deviation and a lower maximal velocity for participants with DCP. This is the first study to assess the psychometric properties of upper limb kinematics in children and adolescents with DCP, showing that children with DCP show higher variability during task execution, requiring a minimum of eight repetitions. However, their variable movement pattern can be reliably captured within-and between-sessions, confirming the potential of three-dimensional motion analysis for assessment of rehabilitation interventions in DCP.

Eye movements and stress during eye-tracking gaming performance in children with dyskinetic cerebral palsy.

AIM: This study aimed to explore eye movements and stress during eye-tracking gaming performance in children with dyskinetic cerebral palsy (CP) compared with typically developing children, and associations between eye-tracking performance, eye movements, stress, and participants' characteristics. METHOD: This cohort study included 12 children with dyskinetic CP aged 5 to 12 years (mean age 8 years 7 months, standard deviation [SD] 2 years 3 months) and 23 typically developing children aged 5 to 13 years (mean age 9 years 0 months, SD 2 years 7 months). Participants played 10 eye-tracking games. Tobii X3-120 and Tobii Pro Lab were used to record and analyse eye movements. Stress was assessed through heart rate variability (HRV), recorded during rest, and eye-tracking performance using the Bittium Faros360° ECG Holter device. Eye-tracking performance was measured using gaming completion time. Fixation and saccade variables were used to quantify eye movements, and time- and frequency-domain variables to quantify HRV. Non-parametric statistics were used. RESULTS: Gaming completion time was significantly different (p < 0.001) between groups, and it was negatively correlated with experience (rs  = -0.63, p = 0.029). No significant differences were found between groups in fixation and saccade variables. HRV significantly changed from rest to eye-tracking performance only in typically developing children and not in children with dyskinetic CP. INTERPRETATION: Children with dyskinetic CP took longer to perform the 10 games, especially the inexperienced users, indicating the importance of the early provision of eye-tracking training opportunities. It seems that eye-tracking tasks are not a source of increased stress and effort in children with dyskinetic CP. WHAT THIS PAPER ADDS: Participants with dyskinetic cerebral palsy (CP) took twice as long to perform 10 eye-tracking games than typically developing peers. Participants with dyskinetic CP with previous eye-tracking experience performed the games faster. Fixation and saccade variables were not significantly different between children with and without dyskinetic CP. Heart rate variability showed no differences between rest and performance in participants with dyskinetic CP. Gross Motor Function Classification System, Manual Ability Classification System, and Viking Speech Scale levels were not correlated to the eye movements or stress variables.

Exercise load and physical activity intensity in relation to dystonia and choreoathetosis during powered wheelchair mobility in children and youth with dyskinetic cerebral palsy.

PURPOSE: To explore the relation between exercise load, physical activity intensity, and movement disorders during powered wheelchair (PW) mobility in people with severe dyskinetic cerebral palsy (DCP). METHODS: Ten participants with DCP, 6-21 years old, users of a head/foot steering system were included. Dystonia and choreoathetosis were assessed using the Dyskinesia Impairment Mobility Scale (DIMS), heart rate (HR) was used to assess the exercise load of the tasks on the participants, and the accelerometry-based activity index (AI) to measure the physical activity intensity and energy expenditure during mobility task performance. RESULTS: Neck- and distal arm dystonia showed significant correlations with HR (0.64 < rs < 0.77; 0.009 < p < 0.048), whereas neck- and proximal arm choreoathetosis with AI (0.64 < rs < 0.76, 0.011 < p < 0.044). Total-body AI was strongly correlated to the AI of the arms (0.66 < rs < 0.90, < 0.001 < p < 0.038), but not to the AI of the head. CONCLUSIONS: During PW mobility tasks, dystonia is associated to exercise load and choreoathetosis to physical activity intensity and energy expenditure. Findings highlight the difficulties in measuring exercise load and activity intensity in PW users with DCP due to the involuntary hypertonic and/or hyperkinetic hallmark of the movement disorders. Nevertheless, a relaxed surrounding with minimal distractions during PW training may increase learning efficiency. Future studies with a bigger sample size are highly recommended to fully establish the relationship between the variables and to allow generalizability of results.Implications for rehabilitationDystonia is positively related to heart rate during powered mobility, which may be explained by the hypertonic hallmark of dystonia causing an increase in exercise load.Choreoathetosis is positively related to the physical activity index during powered mobility where the hyperkinetic hallmark of choreoathetosis may lead to an increase in physical activity intensity and energy expenditure.Arm overflow movements are the component which contribute the most to total-body activity index, thus, minimizing these movements may lower the overall energy expenditure during powered mobility.Mobility training in a relaxed surrounding with minimal distractions and minimized arm overflow movements may lead to a less-demanding powered wheelchair mobility experience and increased learning efficiency.

Clinical Presentation of Spasticity and Passive Range of Motion Deviations in Dyskinetic Cerebral Palsy in Relation to Dystonia, Choreoathetosis, and Functional Classification Systems.

Objectives: To map the presence, severity, and distribution of spasticity and passive range of motion (pROM) deviations in dyskinetic cerebral palsy (DCP), and to explore their relation with dystonia, choreoathetosis, and functional abilities.Methods: This cross-sectional study included 53 participants with DCP. Spasticity was assessed with the Modified Ashworth Scale, limited- and increased pROM (hypermobility) with a goniometer, dystonia and choreoathetosis with the Dyskinesia Impairment Scale, gross motor and manual abilities with corresponding functional classification systems.Results: Spasticity and limited pROM were correlated with dystonia of the upper limbs (0.41< rs<0.47, <0.001 < p < .002) and lower limbs (0.31< rs<0.41, 0.002 < p < .025), and both functional systems of gross motor (0.32< rs<0.51, <0.001 < p < .018) and fine manual abilities (0.34< rs<0.44, 0.001 < p < .014). Hypermobility is correlated only with choreoathetosis of the lower limbs (0.44, p = .001).Conclusions: Coexisting spasticity and pROM deviations in DCP are functionally limiting and should be addressed accordingly. Hypermobility may lead to an increased luxation risk.

Dystonia and choreoathetosis presence and severity in relation to powered wheelchair mobility performance in children and youth with dyskinetic cerebral palsy.

INTRODUCTION: Power wheelchairs (PW) with head/foot steering systems are used as an alternative to joysticks in children with severe dyskinetic cerebral palsy (DCP). Mobility training programs are unstandardized to date, and insight on dystonia, choreoathetosis, and mobility performance may lead to greater independent mobility. OBJECTIVE: To map the presence and severity of dystonia and choreoathetosis during PW mobility in DCP and their relation with mobility performance. METHODS: Ten participants with DCP performed four PW mobility tasks using a head/foot steering system. Dystonia and choreoathetosis in the neck and arm regions were evaluated using the Dyskinesia Impairment Mobility Scale (DIMS). PW mobility performance was assessed using time-on-task and the number of errors during performance. The Wilcoxon-signed rank test and the Spearman's correlation coefficients were used to explore differences and correlations. RESULTS: Median levels of dystonia (83.6%) were significantly higher (p < 0.01) than median levels of choreoathetosis (34.4%). Positive significant correlations were found between the Arm Proximal DIMS and the PW mobility experience (rs=-0.92, p < 0.001), and between the Arm Distal DIMS and the number of errors (rs = 0.66, p = 0.039) during mobility performance. CONCLUSIONS: Dystonia is more present and severe during PW mobility than choreoathetosis. The hypertonic hallmark of dystonia may mask the hyperkinetic hallmark of choreoathetosis, resulting in lower median levels. Results may suggest that with an increase in driving experience, children with DCP adopt deliberate strategies to minimize the negative impact of arm overflow movements on mobility performance, however, future research with bigger sample size and additional outcome measures is strongly encouraged.

Preexercise Cycling Protocol Alters Pacing Behavior in Competitive Time Trials.

PURPOSE: The behavior of an opponent has been shown to alter pacing and performance. To advance our understanding of the impact of perceptual stimuli such as an opponent on pacing and performance, this study examined the effect of a preexercise cycling protocol on exercise regulation with and without an opponent. METHODS: Twelve trained cyclists performed 4 experimental, self-paced 4-km time-trial conditions on an advanced cycle ergometer in a randomized, counterbalanced order. Participants started the time trial in rested state (RS) or performed a 10-min cycling protocol at 67% peak power output (CP) before the time trial. During the time trials, participants had to ride alone (NO) or against a virtual opponent (OP). The experimental conditions were (1) RS-NO, (2) RS-OP, (3) CP-NO, and (4) CP-OP. Repeated-measures analyses of variance (P < .05) were used to examine differences in pacing and performance in terms of power output. RESULTS: A faster pace was adopted in the first kilometer during RS-OP (318 [72] W) compared with RS-NO (291 [81] W; P = .03), leading to an improved finishing time during RS-OP compared with RS-NO (P = .046). No differences in either pacing or performance were found between CP-NO and CP-OP. CONCLUSIONS: The evoked response by the opponent to adopt a faster initial pace in the 4-km time trial disappeared when cyclists had to perform a preceding cycling protocol. The outcomes of this study highlight that perceived exertion alters the responsiveness to perceptual stimuli of cyclists during competition.

Effect of knee arthroplasty on sports participation and activity levels: a systematic review and meta-analysis.

OBJECTIVE: Desires and expectations of patients in regard to resume participation in sport activities after knee arthroplasty strongly increased in recent years. Therefore, this review systematically reviewed the available scientific literature on the effect of knee arthroplasty on sports participation and activity levels. DESIGN: Systematic review and meta-analysis. DATA SOURCES: PubMed, Embase, SPORTDiscus and reference lists were searched in February 2019. STUDIES ELIGIBILITY CRITERIA: Inclusion of knee osteoarthritis patients who underwent total knee arthroplasty (TKA) and/or unicondylar knee arthroplasty. Studies had to include at least one preoperative and one postoperative measure (≥1 year post surgery) of an outcome variable of interest (ie, activity level: University of California, Los Angeles and/or Lower Extremity Activity Scale; sport participation: type of sport activity survey). RESULTS: Nineteen studies were included, consisting data from 4074 patients. Knee arthroplasty has in general a positive effect on activity level and sport participation. Most patients who have stopped participating in sport activities in the year prior to surgery, however, do not seem to reinitiate their sport activities after surgery, in particular after a TKA. In contrast, patients who continue to participate in sport activities until surgery appear to become even more active in low-impact and medium-impact sports than before the onset of restricting symptoms. CONCLUSIONS: Knee arthroplasty is an effective treatment in resuming sports participation and physical activity levels. However, to achieve the full benefits from knee arthroplasty, strategies and guidelines aimed to keep patients capable and motivated to participate in (low-impact or medium-impact) sport activities until close before surgery are warranted.

Eye Gaze Gaming Intervention in Children with Dyskinetic Cerebral Palsy: A Pilot Study of Task Performance and Its Relation with Dystonia and Choreoathetosis.

OBJECTIVES: To investigate the operational competences screen navigation and dwell function underlying eye gaze performance, and the relation of dystonia and choreoathetosis with eye gaze performance in children with dyskinetic cerebral palsy (DCP). METHODS: During a 5-week intervention, ten participants with DCP played eye gaze video games daily for 30 minutes. Six games were used to assess task performance, fixation count, and eye movement accuracy during four measurements. Dystonia and choreoathetosis were evaluated using the Dyskinesia Impairment Scale. RESULTS: Eye gaze performance improved over time (p = .013). Moderate to strong within-subject correlations were found between eye movement accuracy and task performance, and between eye movement accuracy and fixation count. No significant correlations were found with the movement disorders. CONCLUSIONS: Eye gaze technology shows great potential to be a successful computer interface for children with severe DCP, thereby potentially improving their communication skills, participation levels, and quality of life.

Inertial Sensor-Based Lower Limb Joint Kinematics: A Methodological Systematic Review.

The use of inertial measurement units (IMUs) has gained popularity for the estimation of lower limb kinematics. However, implementations in clinical practice are still lacking. The aim of this review is twofold-to evaluate the methodological requirements for IMU-based joint kinematic estimation to be applicable in a clinical setting, and to suggest future research directions. Studies within the PubMed, Web Of Science and EMBASE databases were screened for eligibility, based on the following inclusion criteria: (1) studies must include a methodological description of how kinematic variables were obtained for the lower limb, (2) kinematic data must have been acquired by means of IMUs, (3) studies must have validated the implemented method against a golden standard reference system. Information on study characteristics, signal processing characteristics and study results was assessed and discussed. This review shows that methods for lower limb joint kinematics are inherently application dependent. Sensor restrictions are generally compensated with biomechanically inspired assumptions and prior information. Awareness of the possible adaptations in the IMU-based kinematic estimates by incorporating such prior information and assumptions is necessary, before drawing clinical decisions. Future research should focus on alternative validation methods, subject-specific IMU-based biomechanical joint models and disturbed movement patterns in real-world settings.

Athlete-Opponent Interdependency Alters Pacing and Information-Seeking Behavior.

PURPOSE: The influence of interdependency between competitors on pacing decision-making and information-seeking behavior has been explored. This has been done by only altering instructions, and thereby action possibilities, while controlling environment (i.e., competitor behavior) and exercise task. METHODS: Twelve participants performed a 4-km time trial on a Velotron cycle ergometer in a randomized, counterbalanced order alone with no virtual opponent (NO), against a virtual opponent with no restrictions (low athlete-opponent interdependency [OP-IND]), or against a virtual opponent who the participant was permitted to overtake only once during the trial (high athlete-opponent interdependency [OP-DEP]). Information-seeking behavior was evaluated using an SMI eye tracker. Differences in pacing, performance, and information-seeking behavior were examined using repeated-measures ANOVA (P < 0.05). RESULTS: Neither mean power output (NO, 298 ± 35 W; OP-IND, 297 ± 38 W; OP-DEP, 296 ± 37 W) nor finishing time (NO, 377.7 ± 17.4 s; OP-IND, 379.3 ± 19.5 s; OP-DEP, 378.5 ± 17.7 s) differed between experimental conditions. However, power output was lower in the first kilometer of OP-DEP compared with the other experimental conditions (NO, 332 ± 59 W; OP-IND, 325 ± 62 W; OP-DEP, 316 ± 58 W; both P < 0.05), and participants decided to wait longer before they overtook their opponent (OP-IND, 137 ± 130 s; OP-DEP, 255 ± 107 s; P = 0.040). Moreover, total fixation time spent on the avatar of the virtual opponent increased when participants were only allowed to overtake once (OP-IND, 23.3 ± 16.6 s; OP-DEP, 55.8 ± 32.7 s; P = 0.002). CONCLUSION: A higher interdependency between athlete and opponent altered pacing behavior in terms of in-race adaptations based on opponent's behavior, and it induced an increased attentional focus on the virtual opponent. Thus, in the context of exercise regulation, attentional cues are likely to be used in an adaptive way according to their availability and situational relevance, consistent with a decision-making framework based on the interdependence of perception and action.

Pacing Behavior Development of Youth Short-Track Speed Skaters: A Longitudinal Study.

PURPOSE: This study aimed to analyze the development of pacing behavior of athletes during adolescence using a longitudinal design. METHODS: Lap times of male short-track speed skaters (140 skaters, 573 race performances) over two or more 1500-m races during Junior World Championships between 2010 and 2018 were analyzed. Races were divided into four sections (laps 1-3, 4-7, 8-11, and 12-14). Using MLwiN (P < 0.05), multilevel prediction models in which repeated measures (level 1) were nested within individual athletes (level 2) were used to analyze the effect of age (15-20 yr), race type (fast, slow), and stage of competition (final, nonfinal) on absolute section times and relative section times (percentage of total time spent in a section). RESULTS: Between the ages of 15 and 20 yr, total race time decreased (-6.99 s) and skaters reached lower absolute section time in laps 8-11 (-2.33 s) and 12-14 (-3.28 s). The relative section times of laps 1-3 (1.42%) and 4-7 (0.66%) increased and of laps 8-11 (-0.53%) and 12-14 (-1.54%) decreased with age. Fast races were more evenly paced compared with slow races, with slow races having a predominantly slow first half and fast finish. Athletes in finals were faster (2.29 s), specifically in laps 4-7 (0.85 s) and laps 8-11 (0.84 s). CONCLUSION: Throughout adolescence, short-track speed skaters develop more conservative pacing behavior, reserving energy during the start of the race in order to achieve a higher velocity in the final section of the race and a decrease in total race time. Coaches should take into consideration that the pacing behavior of young athletes develops during adolescence, prepare athletes for the differences in velocity distribution between race types, and inform them on how to best distribute their efforts over the different stages of competition.

Head-to-head competition does not affect pacing or performance in 1 km cycling time trials.

Previous research has shown enhanced performance and altered pacing behaviour in the presence of a virtual opponent during middle-distance cycling time trials with a duration of 2 min and longer. The purpose of this study was to determine whether these effects are also present in cycling time trials of shorter duration. Twelve physically active men completed three 1-km time trials. After a familiarisation trial (FAM), participants performed two experimental conditions: one without opponent (NO) and one with a virtual opponent (OP). Repeated-measures ANOVAs were used to assess differences in pacing and performance using power output and duration (p<0.05). No differences in mean finishing times (FAM: 91.5 ± 7.7 s; NO: 91.6 ± 6.4 s; OP: 90.9 ± 4.9 s; p=0.907) or power output (FAM: 382 ± 111 W; NO: 363 ± 80 W; OP: 367 ± 67; p=0.564) were found between experimental conditions. Furthermore, no differences in pacing profiles between experimental conditions were found (p=0.199). Similarly, rate of perceived exertion did not differ between experimental conditions at any moment (p=0.831). In conclusion, unlike events of a more prolonged duration (>2 min), the presence of an opponent did not affect participants' pacing behaviour in short duration 1-km time trials.

Pacing Behavior of Elite Youth Athletes: Analyzing 1500-m Short-Track Speed Skating.

PURPOSE: To gain insight into the development of pacing behavior of youth athletes in 1500-m short-track speed-skating competition. METHODS: Lap times and positioning of elite short-track skaters during the seasons 2011/2012-2015/2016 were analyzed (N = 9715). The participants were grouped into age groups: under 17 (U17), under 19 (U19), under 21 (U21), and senior. The difference between age groups, sexes, and stages of competition within each age group were analyzed through a multivariate analysis of variance (P < .05) of the relative section times (lap time as a percentage of total race time) per lap and by analyzing Kendall tau-b correlations between intermediate positioning and final ranking. RESULTS: The velocity distribution over the race differed between all age groups, explicitly during the first 4 laps (U17: 7.68% [0.80%], U19: 7.77% [0.81%], U21: 7.82% [0.81%], and senior: 7.80% [0.82%]) and laps 12, 13, and 14 (U17: 6.92% [0.14%], U19: 6.83% [0.13%], U21: 6.79% [0.14%], and senior: 6.69% [0.12%]). In all age groups, a difference in velocity distribution was found between the sexes and between finalists and nonfinalists. Positioning data demonstrated that youth skaters showed a higher correlation between intermediate position and final ranking in laps 10, 11, and 12 than seniors. CONCLUSIONS: Youth skaters displayed less conservative pacing behavior than seniors. The pacing behavior of youths, expressed in relative section times and positioning, changed throughout adolescence and came to resemble that of seniors. Pacing behavior and adequately responding to environmental cues in competition could therefore be seen as a self-regulatory skill that is under development throughout adolescence.

Pacing Decision Making in Sport and the Effects of Interpersonal Competition: A Critical Review.

An athlete's pacing strategy is widely recognised as an essential determinant for performance during individual events. Previous research focussed on the importance of internal bodily state feedback, revealed optimal pacing strategies in time-trial exercise, and explored concepts such as teleoanticipation and template formation. Recently, human-environment interactions have additionally been emphasized as a crucial determinant for pacing, yet how they affect pacing is not well understood. Therefore, this literature review focussed on exploring one of the most important human-environment interactions in sport competitions: the interaction among competitors. The existing literature regarding the regulation of exercise intensity and the effect of competition on pacing and performance is critically reviewed in this paper. The PubMed, CINAHL and Web of Science electronic databases were searched for studies about pacing in sports and (interpersonal) competition between January 2000 to October 2017, using the following combination of terms: (1) Sports AND (2) Pacing, resulting in 75 included papers. The behaviour of opponents was shown to be an essential determinant in the regulation of exercise intensity, based on both observational (N = 59) and experimental (N = 16) studies. However, adjustment in the pacing response related to other competitors appears to depend on the competitive situation and the current internal state of the athlete. The findings of this review emphasize the importance of what is happening around the athlete for the outcome of the decision-making process involved in pacing, and highlight the necessity to incorporate human-environment interactions into models that attempt to explain the regulation of exercise intensity in sports and exercise.

The Effect of Preceding Race Efforts on Pacing and Short-Track Speed Skating Performance.

PURPOSE: To examine whether preceding high-intensity race efforts in a competitive weekend affect pacing behavior and performance in elite short-track speed skaters. METHODS: Finishing and intermediate lap times were gathered from 500-, 1000-, and 1500-m short-track speed skating world cups during the seasons 2011-2016. The effect of preceding races on pacing behavior and performance was explored using 2 studies. Study I: The effect of competing in extra races due to the repechage (Rep) system, leading to an increased number of high-intensity race efforts prior to the subsequent main tournament race, was explored (500-m, n = 32; 1000-m, n = 34; and 1500-m, n = 47). Study II: The performance of skaters over the tournament days was evaluated (500-m, n = 129; 1000-m, n = 54; and 1500-m, n = 114). For both analytic approaches, a 2-way repeated-measures analysis of variance was used to assess differences in pacing and performance within skaters over the races. RESULTS: An additional number of preceding high-intensity race efforts due to the Rep system reduced the qualification percentage in the first main tournament race for the next stage of competition in all events (500-m, direct qualification = 57.3%, Rep = 25.0%; 1000-m, direct = 44.2%, Rep = 28.3%; and 1500-m, direct = 27.1%, Rep = 18.2%) and led to a decreased pace in the initial 2 laps of the 500-m event. By contrast, tournament day (Saturday vs Sunday) only affected the pacing behavior of female skaters during the 1500-m event. CONCLUSION: High-intensity race efforts earlier in the day affected pacing and performance of elite skaters, whereas the effect of high-intensity race efforts from the previous day seemed to be only marginal.

Racing an Opponent: Alteration of Pacing, Performance, and Muscle-Force Decline but Not Rating of Perceived Exertion.

PURPOSE: Performing against a virtual opponent has been shown to invite a change in pacing and improve time-trial (TT) performance. This study explored how this performance improvement is established by assessing changes in pacing, neuromuscular function, and perceived exertion. METHODS: After a peak-power-output test and a familiarization TT, 12 trained cyclists completed two 4-km TTs in randomized order on a Velotron cycle ergometer. TT conditions were riding alone (NO) and riding against a virtual opponent (OP). Knee-extensor performance was quantified before and directly after the TT using maximal voluntary contraction force (MVC), voluntary activation (VA), and potentiated doublet-twitch force (PT). Differences between the experimental conditions were examined using repeated-measures ANOVAs. Linear-regression analyses were conducted to associate changes in pacing to changes in MVC, VA, and PT. RESULTS: OP was completed faster than NO (mean power output OP 289.6 ± 56.1 vs NO 272.2 ± 61.6 W; P = .020), mainly due to a faster initial pace. This was accompanied by a greater decline in MVC (MVC pre vs post -17.5% ± 12.4% vs -11.4% ± 10.9%, P = .032) and PT (PT pre vs post -23.1% ± 14.0% vs -16.2% ±11.4%, P = .041) after OP than after NO. No difference between conditions was found for VA (VA pre vs post -4.9% ± 6.7% vs -3.4% ± 5.0%, P = .274). Rating of perceived exertion did not differ between OP and NO. CONCLUSION: The improved performance when racing against a virtual opponent was associated with a greater decline in voluntary and evoked muscle force than riding alone, without a change in perceived exertion, highlighting the importance of human-environment interactions in addition to one's internal state for pacing regulation and performance.

Objectifying Tactics: Athlete and Race Variability in Elite Short-Track Speed Skating.

PURPOSE: To objectively capture and understand tactical considerations in a race, the authors explored whether race-to-race variation of an athlete and the variation of competitors within a race could provide insight into how and when athletes modify their pacing decisions in response to other competitors. METHODS: Lap times of elite 500-, 1000-, and 1500-m short-track speed-skating competitions from 2011 to 2016 (N = 6965 races) were collected. Log-transformed lap and finishing times were analyzed with mixed linear models. To determine within-athlete race-to-race variability, athlete identity (between-athletes differences) and the residual (within-athlete race-to-race variation) were added as random effects. To determine race variability, race identity (between-races differences) and the residual (within-race variation) were added as random effects. Separate analyses were performed for each event. RESULTS: Within-athlete race-to-race variability of the finishing times increased with prolonged distance of the event (500-m, CV = 1.6%; 1000-m, CV = 2.8%; 1500-m, CV = 4.1%), mainly due to higher within-athlete race-to-race variability in the initial phase of 1000-m (3.3-6.9%) and 1500-m competitions (8.7-12.2%). During these early stages, within-race variability is relatively low in 1000-m (1.1-1.4%) and 1500-m (1.3-2.8%) competitions. CONCLUSION: The present study demonstrated how analyses of athlete and race variability could provide insight into tactical pacing decisions in sports where finishing position is emphasized over finishing time. The high variability of short-track skaters is a result of the decision to alter initial pacing behavior based on the behavior of other competitors in their race, emphasizing the importance of athlete-environment interactions in the context of pacing.