Browse

The aim of this study was to describe how major leg muscle activities are altered after learning a novel one-legged pedaling task. Fifteen recreational cyclists practiced one-legged pedaling trials during which they were instructed to match their applied pedal force to a target direction perpendicular to the crank arm. Activity in 10 major leg muscles was measured with surface electromyography electrodes. Improved upstroke task performance was obtained by greater activity in the hip and ankle flexor muscles, counteracting the negative effects of gravity. Greater quadriceps activities explained improved targeting near top dead center. Reduced uniarticular knee and ankle extensor downstroke activities were necessary to prevent freewheeling. Greater hamstring and tibialis anterior activities improved targeting performance near the bottom of the pedal stroke. The activity patterns of the biarticular plantarflexors changed little, likely due to their contributions as knee flexors for smooth upstroke pedaling motion. These results add to our understanding of how the degrees of freedom at the muscle level are altered in a cooperative manner to overcome gravitational effects in order to achieve the learning goal of the motor task while satisfying multiple constraints—in this case, the production of smooth one-legged pedaling motion at the designated mechanical task demands.

Deficits in motor performance have been well documented in individuals with Down syndrome (DS). However, only a few studies have focused on manipulative skills and older adults in this population. Given the associations between manipulative skills and daily living activities, more work is needed to examine the aging effect on individuals with DS. A total of 54 adults with DS participated in this study. The results indicated that older participants showed more lateralization than younger participants. They exhibited superior dominant hand preference compared to younger participants. In addition, participants with DS with high verbal ability had better performance in manual dexterity and handgrip force. Therefore, in the clinical setting, assessing mental age may help in identifying individuals with DS at a higher risk of motor impairment. Future work should examine additional determinants with a large sample size to understand the development of manipulative skills in individuals with DS. Furthermore, additional studies are needed to investigate the associations between mental age and other cognitive functions and motor performance in this population.

As a step toward understanding the developmental relationship between handedness and language lateralization, this longitudinal study investigated how infants (N = 21) move their hands in noncommunicative and communicative situations at 2 weeks and at 3 months of age. The authors looked at whether left-right asymmetry in hand movements and in duration of self-touch appeared across conditions and whether the direction of asymmetry depended on the communicative nature of the situation. The authors found that asymmetries appeared less consistently than suggested in literature and did not only depend on the communicative nature of the situation. Instead, hand activity and self-touch patterns depended on age, the presence of the mother, the degree of novelty of the situation, and the presence of an object. The results partly support previous studies that pointed out an early differentiation of communicative hand movements versus noncommunicative ones in infants. It is in terms of the amount of global hand activity, rather than in those of the laterality of hand movements that this differentiation emerged in this study. At 3 months, infants moved their hands more in the communicative conditions than in the noncommunicative conditions and this difference appeared as a tendency already at 2 weeks of age.

The authors investigated the kinematic characteristics of the standing long jump in preschool children. Sixty 4-year-old children (boys: 30 and girls: 30) and sixty 5-year-old children (boys: 30 and girls: 30) participated in the present study. The authors focused on three differences in kinematics: between 4- and 5-year-old children, between boys and girls, and between high and low jumping performance groups at the same age. The kinematic data included the maximum flexions of the knee and hip before takeoff, at takeoff, and on landing; angular displacement of the upper body; takeoff speeds in horizontal and vertical directions; and takeoff angle of the greater trochanter. Anthropometric variables and kinematic data were separately analyzed with factors of age, sex, and group. The authors also performed multiple regression analysis to identify predictors of the jump distance. The movement speed of the greater trochanter in a horizontal direction, the maximum flexion angle of the hip before takeoff, and the hip angle on landing were identified as significant predictors of the jump distance among young children. These findings suggest that knowing how to use the hip and awareness of the horizontal direction are key factors to improve the long jump distance in young children.

The aim of this study was to determine the validity and reliability of the Perceived Movement Skill Competence scales for Iranian children. In particular, the scales aligned with the second and third versions of the Test of Gross Motor Development and the active play skills. The total sample was 314 children aged 4–8 years (M _age = 6.1 years, SD = 1.1). From this, a random sample of 74 were recruited for face validity. The data from the remaining 240 children were used to establish construct validity using Bayesian Structural Equation Modeling. The data from a second random subsample of 126 children were used to investigate Perceived Movement Skill Competence reliability using ordinal alpha coefficients and intraclass correlations coefficients. The majority of children correctly identified the skills and understood most of the pictures. Internal consistency was very good (from 0.81 to 0.95) for all scales and subscales. Test–retest reliability was excellent with intraclass correlation coefficient values above .85. For construct validity, the initial hypothesized models for three-factor (i.e., locomotor, object control, and play skills) and two-factor (i.e., locomotor and object control) models showed a reasonable fit. The pictorial scales for Perceived Movement Skill Competence are valid and reliable for Iranian young children.

Current methods to understand implicit motor sequence learning inadequately assess motor skill acquisition in daily life. Using fixed sequences in the serial reaction time task is not ideal as participants may become aware of the sequence, thereby changing the learning from implicit to explicit. Probabilistic sequences, in which stimuli are linked by statistical, rather than deterministic, associations can ensure that learning remains implicit. Additionally, the processes underlying the learning of motor sequences may differ based on sequence structure. Here, the authors compared the learning of fixed and probabilistic sequences to randomly ordered stimuli using a modified serial reaction time task. Both the fixed and probabilistic sequence groups exhibited learning as indicated by decreased response time and variability. In the initial stage of learning, fixed sequences exhibited both online and offline gains in response time; however, only the offline gain was observed during the learning of probabilistic sequences. These results indicated that probabilistic structures may be learned differently from fixed structures and have important implications for our current understanding of motor learning. Probabilistic sequences more accurately reflect motor skill acquisition in daily life, offer ecological validity to the serial reaction time framework, and advance our understanding of motor learning.

The adoption of compensatory movement patterns occurs when limitations in mobility, stability, or motor control prevent proper motion from occurring. These dysfunctional movements may inhibit fundamental motor skill development and negatively influence perceived movement competence, impeding the development of physical literacy. Therefore, this study examined the relationship between functional movement and perceived and actual motor skill competence in young adolescents. Functional movement proficiency was determined using the Functional Movement Screen (FMS^™), which provides three variables of interest: (a) FMS^™ total score, (b) number of asymmetries, and (c) number of movement pattern dysfunctions. Perceived physical competence was assessed through the Children and Youth Physical Self-Perception Profile. Finally, the Get Skilled: Get Active process-oriented motor skill assessment was used to evaluate vertical jump, kick, run, and overhand throw proficiency. A significant positive correlation between FMS^™ total score and vertical jump performance was found. A positive relationship was also found between the number of asymmetries and overhand throw performance. The Children and Youth Physical Self-Perception Profile constructs of body attractiveness and physical condition were positively associated with FMS^™ total score, and physical condition was also shown to be inversely related to the number of movement pattern dysfunctions. Results suggest that functional movement may underpin movement competence and confidence.

Missing data incidents are common in experimental studies of motor learning and development. Inadequate handling of missing data may lead to serious problems, such as addition of bias, reduction in power, and so on. Thus, this study aimed to conduct a systematic review of the past (2007) and present (2017) practices used for reporting and analyzing missing data in motor learning and development. For this purpose, the authors reviewed 309 articles from five journals focusing on motor learning and development studies and published in 2007 and 2017. The authors carefully reviewed each article using a six-stage review process to assess the reporting and analyzing practices. Reporting of missing data along with reasons for their presence was consistently high across time, which slightly increased in 2017. Researchers predominantly used older methods (mainly deletion) for analysis, which only showed a small increase in the use of newer methods in 2017. While reporting practices were exemplary, missing data analysis calls for serious attention. Improvements in missing data handling may have the merit to address some of the major issues, such as underpowered studies, in motor learning and development.