Cathodal transcranial direct current stimulation over the Cz increases joint flexibility

Area of Science:

• Neuroscience
• Motor Control
• Biomechanics

Background:

• Joint flexibility is influenced by both mechanical and neural elements.
• The precise role of neural factors, particularly the sensorimotor cortex, in joint flexibility remains unclear.
• Understanding neural contributions is crucial for developing targeted interventions for movement disorders.

Purpose of the Study:

• To investigate the involvement of the sensorimotor cortex in joint flexibility.
• To determine if transcranial direct current stimulation (tDCS) over the Cz area modulates ankle and wrist flexibility.
• To differentiate neural from mechanical contributions to joint flexibility.

Main Methods:

• Eight healthy male participants underwent passive dorsiflexion tests for ankle and wrist range of motion.
• Passive torque was measured to assess mechanical resistance to dorsiflexion.
• Anodal, cathodal, and sham transcranial direct current stimulation (tDCS) were applied over the Cz area for 10 minutes at 2.0mA.

Main Results:

• Cathodal tDCS over Cz significantly increased ankle range of motion by 10.5%.
• No significant changes in wrist range of motion were observed with any tDCS condition.
• Passive torque measurements remained unchanged, indicating that observed flexibility changes were not due to altered mechanical properties.

Conclusions:

• Cathodal tDCS over the sensorimotor cortex Cz area influences joint flexibility, specifically in the ankle.
• The findings suggest that neural factors, potentially related to joint position sense or pain perception, are modulated by sensorimotor cortex stimulation.
• This study supports the hypothesis that the sensorimotor cortex is involved in the neural control of joint flexibility.