Related Experiment Video
Updated: May 26, 2026
Assessing Corticospinal Excitability During Goal-Directed Reaching Behavior
Published on: December 2, 2022
The development of rhythm regularity, neuromuscular strategies, and movement smoothness during repetitive reaching in
Robyn Traynor1, Victoria Galea, Michael R Pierrynowski
1McMaster Institute of Neuroscience Discovery and Study, McMaster University, Hamilton, Canada.
Insights
Children exhibit greater variability and less smooth movements when reaching, indicating challenges in controlling distal muscles. Adults demonstrate more optimal neuromuscular strategies for smoother, consistent reaching.
Area of Science:
- Motor control development
- Biomechanics
- Neuroscience
Background:
- Paced coordinated reaching involves synchronizing movement with external cues.
- Key developmental aspects include movement entrainment, muscle activation synchrony, and smoothness.
Purpose of the Study:
- To investigate the developmental trajectory of paced reaching in children.
- To compare the motor control strategies of children and adults during a reaching task.
Main Methods:
- Thirty children (5-10 years) and ten adults performed timed reaching tasks.
- Electromyography (EMG) and motion capture analyzed muscle activation and movement smoothness.
- Cross-correlations assessed muscle pair synchrony, while accelerations quantified movement smoothness.
Main Results:
- Younger children (5-6 years) displayed the highest temporal variability in reaching.
- Adults showed more consistent muscle activation patterns and smoother upper arm movements.
- Hand and forearm segments exhibited the greatest movement variability across all age groups.
Conclusions:
- Children's difficulties with distal musculature control contribute to increased temporal variability and reduced movement smoothness.
- Adults employ more efficient neuromuscular strategies for reaching, resulting in superior movement consistency and smoothness.
Introduction:
This study examined the development of paced coordinated reaching characterized by the successful entrainment of the movement to an external pacer, synchronous muscle activations and movement smoothness.
Methods:
Thirty children, 5-10 years of age, and ten adults were instructed to repeatedly reach for and move an object from a lower shelf to an upper shelf in time to a metronome. Surface electromyography data were recorded. Amplitude and cross-correlations were calculated on three muscle pairs crossing the shoulder and elbow. A motion capture system captured the space curve accelerations of hand, forearm and upper arm segments to quantify movement smoothness.
Results:
The 5-6 year old children showed the greatest amount of temporal variability, followed by 7-10 year olds and then the adults. Correlations between muscle pairs stabilizing the shoulder girdle were higher in each group as compared to the other two muscle pairs but the correlations for all pairs were consistently higher for adults. Movement smoothness for children 9-10 years of age was closer to an adult-like pattern with respect to control of the upper arm, but the hand segment had the greatest variability across groups.
Conclusions:
The increased temporal variability and decreased movement smoothness of the hand and forearm segments suggest that control of more distal musculature may be more difficult in children. The neuromuscular strategies adopted by adults were more optimal than those adopted by children as reflected by smoother and more consistent reaching.
