This is the first study to compare lower limb joint position sense and kinematic control of 13 to 14-year-old adolescents in a large cross-sectional sample with quantitative measures. Importantly, in agreement with previous findings, there were no differences between categorized groupings for TD and DCD adolescents. Although there was a significant correlation found between MC and kinematic control, no correlation was found between MC and knee joint position sense. A significant negative correlation was found between normalized jerk (NJ) and MC in the categories of manual dexterity, balance function, and total score of the mABC-2. Furthermore, the 80 adolescents categorized in the DCD group were found to have similar knee joint position sense and kinematic control of the lower limbs with those who are typically developed, with variability in measures observed in both groups.

In regards to joint position sense and MC, Goble et al. found that children (8–10 years) demonstrated larger position error (PE) with shorter duration and more velocity peaks compared to older adolescents (16–18 years) during an active elbow position matching task, indicating that age-related improvements in proprioceptive acuity continue throughout childhood and adolescence [26,27,28]. Another article stated that standard variation of position error (SDPE) of the wrist was significantly associated with the aiming & catching and balance portions of the mABC-2 score, but not with position error (PE) [29]. A large sample size study (n = 354) also demonstrated improvement in developmental elbow joint acuity in children aged 5–18 years for SDPE but not for PE [30]. One of the main objectives of the present study was to determine the relation between joint position sense and MC, and our results showed that neither PE nor SDPE of the knee joint correlated with any category or the total score of mABC-2. A possible reason for these results might be that the mABC-2 does not specifically target knee joint position sense or performance, but rather targets overall upper and lower limb movement. The manual dexterity and aiming & catching tasks of the mABC-2 mainly assess upper limb fine movement acuity, accuracy, speed, and coordination, whereas the balance tasks mainly focus on lower limb speed and coordination, and postural control and adjustment. Test of joint position sense, however, is not reflected in any of the components of the mABC-2 directly, and thus may not a representative picture of MC in adolescents. In addition, joint position sense reflects somatosensory input whereas MC represents sensorimotor output. A previous anatomical study found that although these neural networks overlap, they are not identical, perhaps indicating little association between proprioceptive function and MC, as reflected in the results of our study [9].

The present study also assessed the relationship between kinematic control and MC. Age has been found to be a factor in kinematic control, with better scores seen in older children, however, very little developmental studies have looked at adolescent kinematic performance [26,27,28]. Normalized jerk, which is the kinematic measurement of movement smoothness, was recorded during in our study. Results showed weak but significant negative correlation between NJ and MC in the categories of manual dexterity, balance function, and total mABC-2 score, indicating that a better overall MC is associated with better kinematic control in movement tasks.

Furthermore, the present study analyzed differences in joint position sense and kinematic control between adolescents with and without DCD and found no significant group differences in either category. Variability was seen within groups, with DCD adolescents exhibiting greater variability compared to TD. Tseng et al. found that in children between 9 and 11 years of age, those categorized in the DCD group performed significantly poorer in SDPE than the TD group for wrist and elbow joint position sense, but there was no group difference in PE [29, 31]. Chen et al. found significant negative correlations between proprioceptive acuity of the knee and ankle joint and balance function in children with DCD compared to TD; however, participants were spread across two age bands (7–10 years and 11–16 years) of the mABC-2 9. In the present study, we proved that 13- to 14-year-old adolescents with and without DCD showed similar performance for PE and SDPE of the knee joint in a movement reproduction task. We may conclude that by the time of early adolescence, considering our findings of a relationship of kinematic control to MC, that there is a continuum between these measures with some variability rather than a distinct grouping Furthermore, as joint position sense measures small changes in movement, these differences may no longer be apparent in adolescence. Although no significant differences were found between groups in the present study, variability was higher for the DCD population (Table 5). This may indicate that the knee joint proprioceptive task may not be challenging enough to elicit differences between TD and DCD adolescents. A previous imaging study found that cortical processes seen in children with DCD are markedly different from those in TD children [32], which indicates the possible use of compensatory strategies during motor performance to mask for movement insufficiencies, especially in older children with DCD. In regard to kinematic control, our results are consistent with a previous upper limb study that showed that DCD and TD children exhibited similarities in motor performance, with group differences demonstrated only for movement smoothness (NJ). Although the present study did not conduct statistical analysis between DCD and TD groups for NJ, the coefficient of variation (CV) based on our data indicated that the DCD group showed larger CV on NJ than the TD group (CV = 8.59 and 3.79, respectively), representing that DCD adolescents had larger variation in movement smoothness [32]. Though overall performances of active movement between children with and without DCD were similar, results from previous studies indicated the possibility that children with DCD require greater engagement of motor cortical areas to control movement after initiation [32]. Differences in performance between groups may be more apparent in activities that require more complex and technical skills, such as in sports, which may have further implications on social participation, especially at a turning point in adolescent growth.

Lastly, this was a large sample size study which crossed 3 local schools in UK. According to mABC-2 norm, 80 out of 427 adolescents identified as being in the 5th percentile, and are indicated as having significant movement difficulty. Although a large number of adolescent participants were categorized as DCD with significant movement difficulty, they did not show significant group difference in either joint position sense or kinematic performance when compared with TD adolescents during the movement reproduction task (Table 5). Although studies have confirmed the validity and reliability of the mABC-2 for the younger age bands and found significant motor differences between DCD and TD children, the subjects in these studies are typically spread across a wide age band, and mainly focus on upper extremity movement [33]. There is insufficient evidence on the validity of the mABC-2 for the adolescent age band. Furthermore, the similarities in motor competence between DCD and TD children may be less apparent because adolescents are at a critical stage when internal motor processes mature rapidly and when external factors play a key role in complex motor skill development. This may also indicate that mABC-2 norms do not reflect the full picture of motor competency in adolescents. Further studies assessing the mABC-2 for adolescents are needed to expand on our findings. Finally, our sample were probable DCD which may have affect some relationships.

In summary, our study highlights on the correlation between MC, joint position sense, and kinematic control in adolescents, particularly those with DCD. We observed a stronger association between MC and kinematic control during movement tasks compared to joint position sense, suggesting that interventions focusing on improving kinematic control may significantly benefit adolescents with DCD, aiding in the development of personalized rehabilitation programs within clinical settings. Additionally, the robustness of our findings is supported by the large sample size, enhancing the generalizability of our results.

Furthermore, our findings extend beyond hospital environments, providing guidance for interventions aimed at fostering physical activity and motor skill development among adolescents in educational and community settings. However, there were limitations. Joint position sense is challenging to measure at scale and could be affected by internally predicted sensory feedback, afferent sensory feedback, or their integration [34]. The present study used an active, rather than passive, providing motor cues that aid the nervous system in predicting movement outcomes [30]. However, this method may be influenced by short-term memory and might not offer a precise measure of proprioceptive acuity [30]. Further research is needed to assess its validity and reliability in measuring lower extremity joint position sense. Additionally, incorporating peri- and postnatal history assessment in future research could provide valuable insights into early developmental factors influencing MC and movement control in adolescence. An important limitation of our study is the inclusion of “probable DCD” cases. While this categorization was necessary due to the lack of a definitive diagnosis in some participants, it may introduce variability in the data. In the present study, mABC-2 was used to assess probable DCD, which is considered as a supportive instrument for DCD diagnosis [35, 36]. Future studies should include additional diagnostic tools and steps such as DSM-5TR criteria to confirm DCD diagnosis and ensure the population corresponds to DCD more accurately.

Despite these limitations, our findings highlight the clinical relevance of considering kinematic control in interventions targeting movement difficulties in adolescents. Future studies should explore the validity and reliability of measurement methods for joint position sense in lower extremities and investigate the impact of more complex motor performance on social participation, particularly in adolescents with DCD [9].