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Coordination between arm-trunk and trunk-leg is important for effective longswing performance. This research describes inter-segmental coordination changes after a practice period of longswing on high bar in a novice cohort. Novices were divided by initial skill level (talent) into two groups: spontaneously-talented, (ST, n = 10, closer to expert performance) and non-spontaneously-talented (NST, n = 15). Additionally, post-practice longswing coordination was compared to expert gymnasts (n = 9). Longswing amplitude and coordination (inter-joint reversal points and continuous relative phase, CRP) were assessed for pre- and post-practice sessions. ANOVAs showed similar practice effects in swing enlargements for the ST (11%) and NST (18%), but inter-joint reversal points and positive area in CRP during the downswing were different. Due to practice, the ST group paired shoulder and hip reversal points (events) during the downswing closer and with larger velocity of the arm in relation to the trunk than the NST group. The NST failed to modify coordination probably due to a large variability at the beginning of the downswing. Given a similar amount of practice, talent could help to achieve the right temporal events' sequence during downswing, which would allow the exploration of different segmental coordination. However, upswing coordination of the novice groups (ST and NST) requires more focused practice to achieve expert levels than downswing, especially the arm-trunk coordination.

Infants with Down syndrome (DS) are consistently late walkers. The purpose of this investigation was to test the effects of individualized, progressively more intense treadmill training on developmental outcomes in infants with DS. Thirty infants born with DS were randomly assigned to receive lower-intensity, generalized treadmill training or higher-intensity, individualized training implemented by their parents in their homes. Research staff members monitored implementation of training, physical growth, and onset of motor milestones of all infants on a monthly basis. Infants in the higher-intensity, individualized training group increased their stepping more dramatically over the course of training. Infants in the higher-intensity training group attained most of the motor milestones at an earlier mean age. Treadmill training of infants with DS is an excellent supplement to regularly scheduled physical therapy intervention for the purpose of reducing the delay in the onset of walking.

Two cohorts of participants were included to investigate the effects of different treadmill interventions on walking onset and gait patterns in infants with Down syndrome (DS). The first cohort included 30 infants with DS (17 males, 13 females; mean age 10mo [SD 1.9mo]) who were randomly assigned to either a lower‐intensity‐generalized (LG) training group, or a higher‐intensity‐individualized (HI) training group. A control (C) group from another study, who did not receive treadmill training, served as the control (eight males, seven females; mean age 10.4mo [SD 2.2mo]). Mean age at walking onset was 19.2, 21.4, and 23.9 months for the HI, LG, and C groups respectively. At walking onset the HI group was significantly younger than the C group (p=0.011). At the gait follow‐up that was conducted between 1 and 3 months after walking onset, three groups significantly different in overall gait patterns (p=0.037) were examined by six basic gait parameters including average velocity, stride length, step width, stride time, stance time, and dynamic base. Post‐hoc analyses demonstrated that stride length was the gait parameter largely contributing to this overall group difference (p=0.033), and the HI group produced a significantly longer stride length than the C group (p=0.030). In conclusion, the HI treadmill intervention significantly promoted earlier walking onset and elicited more advanced gait patterns (particularly in stride length) in infants with DS.

Infants with Down syndrome (DS) have delayed walking and produce less-coordinated walking patterns. The aim of this study was to investigate whether 2 treadmill interventions would have different influences on the development of joint kinematic patterns in infants with DS. Thirty infants with DS were randomly assigned to a lower-intensity, generalized (LG) treadmill training group (LG group) or a higher-intensity, individualized (HI) treadmill training group (HI group) and trained until walking onset. Twenty-six participants (13 in each group) completed a 1-year gait follow-up assessment. During the gait follow-up assessment, reflective markers were placed bilaterally on the participants to measure the kinematic patterns of the hip, knee, and ankle joints. Both the timing and the magnitude of peak extension and flexion at the hip, knee, and ankle joints, as well as peak adduction and abduction at the hip joint, in the 2 groups were compared. Both the LG group and the HI group showed significantly advanced development of joint kinematics at the gait follow-up. In the HI group, peak ankle plantar flexion occurred at or before toe-off, and the duration of the forward thigh swing after toe-off increased. Joint kinematics in the lower extremities were evaluated in this study. It would be interesting to investigate the effect of treadmill interventions on kinematic patterns in the trunk and arm movement. The timing of peak ankle plantar flexion (before toe-off) in the HI group implies further benefits from the HI intervention; that is, the HI group may use mechanical energy transfer better at the end of stance and may show decreased hip muscle forces and moments during walking. It was concluded that the HI intervention can accelerate the development of joint kinematic patterns in infants with DS within 1 year after walking onset.

[...]we will lack therapeutic approaches for targeted interventions. (2) The sensorimotor system controls posture through muscles which produce relative movements between body segments. [...]we would argue that the mechanisms controlling human posture should be studied by directly analyzing movements and muscle activations, rather than through variables which the sensorimotor system can only indirectly affect. For upright standing it was demonstrated that the movement patterns extracted from the PCA closely approximate the classical ankle- and hip movement strategies (Federolf et al., 2013), but also for dynamic movements the eigenvectors provide a suitable reference system to assess stability (Federolf et al., 2012a), adaptability (Ó’Reilly and Federolf, 2021) or symmetry (Ó’ Reilly, 2021). Since the eigenvectors form a linear, orthonormal coordinate system, velocity and acceleration of postural changes can easily be calculated through simple differentiation (Federolf, 2016; Longo et al., 2019), thus the PMs provide a mechanically sound approach for quantifying postural states and changes therein.

Background/objectivesPoorer motor development is reported in infants with iron deficiency (ID). The role of timing, duration and severity is unclear. We assessed relations between ID timing, duration, and severity and gross motor scores, neurological integrity, and motor behavior quality at 9 months.Subjects/methodsIron status was determined at birth and 9 months in otherwise healthy term Chinese infants. The 9-month motor evaluation included the Peabody Developmental Motor Scale (PDMS-2), Infant Neurological International Battery (INFANIB), and motor quality factor. Motor outcomes were analyzed by ID timing (fetal–neonatal, infancy), duration, and severity. For severity, we also considered maternal iron status.ResultsThe data were available for 1194 infants. Iron status was classified as fetal–neonatal and infancy ID (n = 253), fetal–neonatal ID (n = 256), infancy ID (n = 288), and not ID (n = 397). Compared with not ID, infants with fetal–neonatal or infancy ID had lower locomotion scores (effect size ds = 0.19, 0.18) and those with ID in both periods (longer duration) had lower locomotion and overall PDMS-2 gross motor scores (ds = 0.20, 0.18); ID groups did not differ. More severe ID in late pregnancy was associated with lower INFANIB Vestibular function (p = 0.01), and total score (p = 0.03). More severe ID in infancy was associated with lower scores for locomotion (p = 0.03), overall gross motor (p = 0.05).ConclusionsFetal–neonatal and/or infancy ID was associated with lower overall gross motor development and locomotion test scores at 9 months. Associations with ID severity varied by ID timing: more severe ID in late pregnancy, poorer neurological integrity; more severe ID in infancy, poorer gross motor development.

An individual's a priori talent can affect movement performance during learning. Also, task requirements and motor-perceptual factors are critical to the learning process. This study describes changes in high bar swing performance after a 2-month practice period. Twenty-five novice participants were divided by a priori talent level (spontaneous-talented [ST] and nonspontaneous-talented [NST]) and compared to experienced gymnasts. Additionally, we assessed their perception of their performance level before and after practice. We defined three events independently for hip (H) and shoulder (S) angle joints and for the lag between consecutive events (phases [P]): the smallest angle during downswing (P1H, P1S), the largest angle after P1 (P2H, P2S), and the smaller angle during upswing (P3H, P3S). Movement performance variables were the maximum elevation on the downswing (Pi) and the upswing (Pf), and the total path between both (swing amplitude). Data were collected during pre-and postpractice sessions by two video cameras. At the end of both sessions, participants drew a sketch to represent their perception of their performance level relative to the Pi, Pf, and the hip events. Results showed a similar practice effect in the swing amplitude in both novice groups. However, the ST group's performance and perception variables on the downswing improved more than the NST group due to practice. This study suggests that (a) downswing improvements were easier than in the upswing, possibly due to familiarity of the visual reference in combination with proprioceptive feedback; and (b) being ST may involve a better or faster gain in perception of self-action compared to NST.

This study investigated how newly walking toddlers with Down syndrome (DS), after different treadmill interventions, adopted clearance strategies and modified anticipatory locomotor adjustment patterns to negotiate an obstacle in their travel path. Thirty infants with DS (about 10 months of age) were recruited and randomly assigned to either a lower-intensity, generalized (LG) treadmill training group, or a higher-intensity, individualized (HI) treadmill training group. Thirteen in each group completed a one-year-gait follow-up after the treadmill intervention. Initially, both groups chose to either crawl or walk over an obstacle. However, walking over the obstacle became their preferred clearance strategy over the course of the gait follow-up even though the height of the obstacle increased from visit to visit. The HI group used the strategy of walking over the obstacle at a considerably higher percentage than the LG group within 6 months after the training. When approaching the obstacle, both groups started to show consistent anticipatory locomotor adjustments about 6 months after the training. Both groups decreased velocity, cadence and step length, and increased step width at the last three pre-obstacle steps. It was concluded that the retention of the HI training effects led the HI group to predominantly walk over an obstacle earlier than the LG group within 6 months after treadmill intervention, and the two groups produced similar anticipatory locomotor adjustments in the last three steps before negotiating the obstacle.

The authors examined the relative success of varying sensory stimulation modalities that they presented via a mobile reinforcement procedure for promoting left-knee extensions in 3-month-old infants. They separated 53 infants into 5 groups. Four groups received contingent unimodal auditory, enhanced auditory, or visual reinforcement or contingent bimodal auditory plus visual (aud + vis) reinforcement. One group (controls) received aud + vis noncontingent reinforcement. The group that received aud + vis contingent reinforcement was most successful in learning the motor task and maintained the highest attention levels. The authors observed few differences in learning and attention within the unimodal groups. The present findings confirm the effectiveness of contingent multisensory stimulation for promoting perception-action coupling in infancy.