Grip and load force coordination in cyclical isometric manipulation task is not affected by the feedback type

Area of Science:

• Neuroscience
• Biomechanics
• Human Motor Control

Background:

• The interplay between grip force (GF) and load force (LF) during object manipulation offers insights into neural control mechanisms.
• Understanding how feedback influences this coordination is crucial for movement control research.

Purpose of the Study:

• To investigate the effect of feedback type (targeting vs. tracking) on grip force-load force coordination and task performance.
• To determine if feedback influences neural mechanisms of movement control during isometric force exertion.

Main Methods:

• Sixteen volunteers performed isometric sinusoidal load force (LF) exertions under targeting and tracking feedback conditions.
• Task performance was measured by absolute errors, and GF-LF coordination was assessed using ratios, cross-correlation, and time lags.
• Two frequencies (0.77 Hz and 1.53 Hz) were used to examine frequency-dependent effects.

Main Results:

• No significant effect of feedback type on GF-LF coordination or task performance was observed.
• Higher frequency (1.53 Hz) resulted in increased absolute errors at force peaks and higher GF-LF ratios.
• Higher frequency also led to lower maximum cross-correlation coefficients (r(max)) between GF and LF.

Conclusions:

• The type of sensory feedback does not alter task performance or GF-LF coordination during isometric force exertion.
• Tracking tasks are recommended for assessing GF-LF coordination with instrumented handles due to their simplicity and provision of additional control indices.