Adolescent Awkwardness: Alterations in Temporal Control Characteristics of Posture with Maturation and the Relation to Movement Exploration

Abstract

A phenomenon called adolescent awkwardness is believed to alter motor control, but underlying mechanisms remain largely unclear. Since adolescents undergo neurological and anthropometrical changes during this developmental phase, we hypothesized that adolescents control their movements less tightly and use a different coordinative structure compared to adults. Moreover, we tested if emerging differences were driven by body height alterations between age groups. Using 39 reflective markers, postural movements during tandem stance with eyes open and eyes closed of 12 adolescents (height 168.1 ± 8.8 cm) and 14 adults were measured, in which 9 adults were smaller or equal than 180 cm (177.9 ± 3.0 cm) and 5 taller or equal than 190 cm (192.0 ± 2.5 cm). A principal component analysis (PCA) was used to extract the first nine principal movement components (PMk). The contribution of each PMk to the overall balancing movement was determined according to their relative variance share (rVARk) and tightness of motor control was examined using the number of times that the acceleration of each PMk changed direction (Nk). Results in rVARk did not show significant differences in coordinative structure between adolescents and adults, but Nk revealed that adolescents seem to control their movements less tightly in higher-order PMk, arguably due to slower processing times and missing automatization of postural control or potential increases in exploration. Body height was found to not cause motor control differences between age groups.

How Do Movement Patterns in Weightlifting (Clean) Change When Using Lighter or Heavier Barbell Loads?—A Comparison of Two Principal Component Analysis-Based Approaches to Studying Technique

“…PCA posture results in time series of scores called principal (postural) positions PP ( Federolf, 2016 ; Haid et al, 2018 ). The score time series were differentiated to obtain postural velocity, PV, and postural acceleration, PA, components ( Federolf, 2016 ; Haid et al, 2018 , 2019 ; Promsri et al, 2018 ; Longo et al, 2019 ; Zago et al, 2019 ; Promsri and Federolf, 2020 ; Wachholz et al, 2020 ).…”

“…Second, the input matrix may consist of posture vectors, e.g., defined by the position of markers placed on all body segments (columns) collected over time, subjects, and trials (rows). The PCA then finds patterns of correlations within the variations of posture vectors as they change over time (PCA posture ) and maps them on movement components/movement synergies ( Maurer et al, 2012 ; Federolf et al, 2014 ; Hsiu-Hui et al, 2016 ; Majed et al, 2017 ; Gløersen et al, 2018 ; Promsri et al, 2018 ; Wachholz et al, 2020 ). To the best of our knowledge, no comparison between these two approaches in application of PCA for technique analysis in sports has been completed so far.…”

Slow walking synergies reveal a functional role for arm swing asymmetry in healthy adults: A principal component analysis with relation to mechanical work

“…The first PM explaining 61.7% of the overall variance was chosen for further analysis only as this primary PM has been identified in previous studies as the basic inverted-pendulum motion of gait and as such is of specific relevance to this study's aims (17,42). With this primary PM the number of zero-crossings in its corresponding PAk time-series were counted for each participant (34,36), thus formulating the independent variable Nk for further analysis. The directional Arm-swing asymmetry index (dASI) was formulated to determine the degree of arm-swing asymmetry during gait.…”

“…The PAk have been of particular interest as they are thought to represent the action of the neuromuscular system (34,35). Among other potential variables, the tightness of neuromuscular control on PMk (Nk) can be determined by the number of zero-crossings (changes in direction) in the corresponding PAk (34,36).…”

Imaging of Pediatric Lower Limb Sports Injuries

“…14,20 Finally, socalled adolescent awkwardness, a period of slower processing of motor commands while at the same time the musculoskeletal changes just mentioned occur, result in reduced standing balance and dynamic control and hence an increase in injuries during the growth spurt. 21…”