Changes in joint kinematics and dynamic postural stability with free and restricted arm movements in children

Effects of arm movement strategies on emotional state and balance control during height-induced postural threat in young adults

BACKGROUND

It is firmly established that postural threat seems to lead to an increased. reliance on an ankle control ('stiffening') strategy. However, little is known about how. postural threat affects performance in challenging tasks that require the use of upper. body postural control strategies for stability. It is logical to assume that in such. conditions, being able to utilise an upper body strategy may reduce the reliance on. such ankle stiffening strategy. Research question The objective of this study was to determine how arm movement. influences balance control during a challenging balance task performed under. conditions of postural threat.

METHODS

Thirty young adults (mean ± SD age; 22.0 ± 4.0 years) balanced in tandem. stance whilst standing at both ground-level (no threat) and 0.8 m above ground. (threat). In both conditions, participants performed the task under two different arm.

POSITIONS

restricted arm movements and free arm movements. Postural sway. amplitude and frequency were calculated to infer postural stiffening response. Selfreported. emotional responses were quantified by assessing balance confidence, fear. of falling, perceived stability, and conscious balance processing.

RESULTS

Independent of arm movements, postural threat evoked an increase in fear of. falling and conscious balance processing, and reductions in balance confidence and. perceived stability. These threat-related changes in emotional state were further. amplified when arm movements were restricted. Whilst significant increases in sway. frequency during threat were observed in both arm conditions, reductions in sway. amplitude were only observed during the restricted arm movement condition.

SIGNIFICANCE

We propose that these responses likely reflect a fear-related cautious. strategy intended to reduce the postural destabilisation associated with individuals. being unable to use their arms to counter any destabilisation, as would normally be the. case in daily life.

Effect of upper extremity constraints on functional and dynamic postural control in children with hemiplegic cerebral palsy

PURPOSE

To compare the effects of upper extremity constraints on functional and dynamic postural control in children with hemiplegic cerebral palsy.

MATERIALS AND METHODS

Twelve children with hemiplegic cerebral palsy and 12 typically developing children ages 5 to 12 years (GMFCS I-II) were evaluated with the Timed Up and Go (TUG) and Biodex Balance System during three upper extremity (UE) conditions: 1) Free UEs (no constraints), 2) Simple UE constraint (unaffected/dominant UE constrained with a sling), and 3) Difficult UE constraint (Simple constraint plus the other UE holding cup of water).

RESULTS

The UE condition had significant effects on Overall Stability Index (OSI) (F_(2,44) = 24.899, p < .001), Medial-Lateral Stability Index (MLSI) (F_(2,44) = 4.380, p = .018), Anterior-Posterior Stability Index (F_(2,44) = 6.187, p = .004), and TUG scores (F_(2,44) = 113.372, p < .001). Group was significant for OSI (F_(1,22) = 7.906, p = .010), MLSI (F_(1,22) = 13.113, p = .002), and TUG (F_(1,22) = 36.282, p < .001).

CONCLUSIONS

The upper extremity appears to have a role in maintaining functional balance and postural stability in children with hemiplegic cerebral palsy and should be considered during intervention programs.

Effect of Arm Movement and Task Difficulty on Balance Performance in Children, Adolescents, and Young Adults

Background

Studies have shown that restricted compared to free arm movement negatively affects balance performance during balance assessment and this is reinforced when the level of task difficulty (e.g., varying stance/walk conditions, sensory manipulations) is increased. However, it remains unclear whether these findings apply to individuals with differences in the development of the postural control system. Thus, we examined the influence of arm movement and task difficulty on balance performance in children, adolescents, and young adults.

Methods

Static, dynamic, and proactive balance performance were assessed in 40 children (11.5 ± 0.6 years), 30 adolescents (14.0 ± 1.1 years), and 41 young adults (24.7 ± 3.0 years) using the same standardized balance tests [i.e., one-legged stance (OLS) time with eyes opened/closed and/or on firm/foam ground, 3-m beam (width: 6, 4.5, or 3 cm) walking backward step number, Lower Quarter Y-Balance test (YBT-LQ) reach distance] with various difficulty levels under free vs. restricted arm movement conditions.

Results

In all but one test, balance performance was significantly better during free compared to restricted arm movement. Arm by age interactions were only observed for the YBT-LQ and post hoc analyses revealed significantly greater performance differences between free and restricted arm movement, especially, in young adults. Arm by age by task difficulty interactions were found for the OLS and the 3-m beam walking backward test. Post hoc analyses showed significantly greater performance differences between free and restricted arm movement during high vs. low levels of task difficulty and this was more pronounced in children and adolescents.

Conclusions

Regardless of age, static, dynamic, and proactive balance performance benefited from arm movements and this was especially noted for youth performing difficult balance tasks.