Journal of Motor Control and Learning
Volume:3 Issue: 1, Winter 2021

Uncontrolled Manifold (UCM) approach has gained a lot of attention in the field of movement variability and related areas of research. The diversity of applications and the need to explore new UCM-based measures along with the advances in mathematical methods in UCM have led to several formulas for UCM outcome measures with different notations and conflicting interpretations. This letter is intended to summarize the most popular indexes while suggesting a unified notation.

 Weak hip external rotation has been speculated to be connected to PFP. However, muscle activity of hip musculature has yet to be investigated during gait with individuals who report PFP.

 The purpose of this study was to compare peak muscle activity in the hip during stance phase of a 10 meter walk between females with and without patellofemoral pain (PFP).

Eight females with PFP and eleven females without PFP volunteered for this study. Peak muscle activity of the adductor longus (AL), tensor fascia latae (TFL), gluteus medius (GMED), and gluteus maximas (GMAX) were measured using surface electromyography (EMG). Participants completed 3 trials of a 10m walk while surface EMG was recorded. Muscle co-activation, total time spent in stance, and total walk time were also compared between groups. Four separate independent sample t-test were conducted to compare participants without PFP (n = 11) and participants with PFP (n = 9) for peak muscle activation, muscle co-activation, total stance time, and total walk time.

Peak muscle activity in the AL, TFL, GMED, and GMAX were not significantly different in female participants with and without PFP. Although, peak TFL muscle activity in participants with PFP (M = 0.1664, SD = 0.11360) was higher compared to participants without PFP (M = 0.1016, SD = 0.5937). There were no statistically significant differences in muscle co-activation or 10m walk time between participants with and without PFP. However, time spent in stance time approached statistical significance, p = 0.059.

There are no differences in peak muscle activity in the AL, TFL, GMED, and GMAX between females with and without patellofemoral pain (PFP) during stance phase of a 10m walk.

Addressing the issue of social responsibility is pleasant and valuable for every human being, and this category has found a special place in the context of sports. To date, different forms of this category have emerged, one of which is social responsibility in the individual dimension, which can be addressed to all sections of society.

Due to the importance of the subject, the purpose of this study was to construct and validate a scale for measuring the social responsibility of famous Iranian athletes.

The methodology of the present study is descriptive-analytical and based on the purpose of applied studies. The statistical population of the present study consisted of physical education students of Tehran, Beheshti, Modares and Kharazmi universities in 3 levels. Structural equations were used to determine the sample size and finally 338 questionnaires were examined. In order to evaluate the validity and reliability of the instrument, indicators such as exploratory factor analysis, confirmatory factor analysis based on structural equation modeling, divergent and convergent validity and Cronbach’s alpha and combined reliability, each of which performs a specific action.

Moreover, the results of all indicators indicated a favorable evaluation of the instrument.

Therefore, it is suggested that researchers in the field of sports management use this standardized tool to assess the level of responsibility of famous Iranian athletes and provide desirable results.

Coordination depends on online performance, and online feedback supports the successful coordination of individuals in joint implementations.

A specific purpose for the research was investigating temporal and spatial parameters in interpersonal coordination.

An applied research was done as a single-stage case study with 14 jumping rope elite boys (13-18 years). The subjects practiced the jumping rope tasks for 8 months so that they could do them properly and without online feedback. This study used a Vicon motion analysis device with six infrared cameras capable to record three-dimensional movements of the legs and rope whirling.

The results of one-way ANOVA showed that with enough practice, even in the absence of feedback, landing position (spatial parameter) and hand-foot time deviation, timing variation in rope whirling, and landing time (temporal parameter) of joint groups will reach an equal level while a significant difference was observed in jump height (spatial parameter) and movement time (temporal parameter) between individuals (P≤0.05).

So, increasing task difficulty, amount and sustainability of inter-personal coordination will increase. Increasing joint task demands, amount and sustainability of interpersonal coordination will increase, and joining individualchr('39')s power will be changed according to individual and joint tasks constraints.

 Investigating factors that affect the performance of professional athletes has always been one of the important fields of sports science.

One of the important questions in this regard is whether athletes are better to be self-aware while performing physical movements or, conversely, this self-awareness as an interfering factor will lead to a decline in their performance.

In the present study, an attempt has been made to examine this issue with an interdisciplinary view based on the physical cognition approach, especially with the application of two models of Dreyfuss (2007) and the meshed architecture (Christensen, Sutton and McIlewin 2016; Gllagher, 2020).

According to the first model, self-awareness will interfere with the performance of skillful movements, and in the opposite model, the performance of movements requires awareness of self, body and position.

Both approaches seem to rightly point to different aspects of awareness in performing movements; although awareness of the current situation is essential for performing movements, overt body awareness interferes with learning and performing movements and can have adverse psychological consequences for athletes in the long run.

One of the most important disorders in children is developmental coordination disorder. In this disorder, motor problems affect childrenchr('39')s daily activities, academic achievement, and health in the absence of any known medical condition or neurological disorder.

This study aimed to investigate the effect of self-modeling with mobile phone on overarm throwing skill in 7-9 years old children with developmental coordination disorder.

Twenty-four children with DCD were selected as purposeful sample and randomly divided into two experimental and one control group. Experimental groups conducted self-modeling with mobile phone under the supervision of a trainer and their parents. The control group trained overarm throwing skill without self-modeling. Training protocol consisted of 5 weeks, three sessions per week and each session included 40 minutes. The process and the product of overarm throwing were measured by the Ulrich test of gross motor development, the second edition, and the accuracy of the throw test.

Covariance test and Bonferroni’s post hoc test showed that there was a significant improvement in the process of overarm throwing skill in the two experimental groups (P<0.05). Comparison of the groups showed that there was no significant difference between the two groups in the throwing process (P>0.05), but both groups had a significant difference with the control group (P<0.05). Comparison of the groups in the product of the throwing skill showed that there was no significant difference between the groups (P>0.05).

In general, the results of this study showed that that self-modeling with mobile phone improves the process of overarm throwing skill in children with developmental coordination disorders. Self-modeling probably facilitates the process of performing and learning skill in these children by creating a representation of the task.