This randomized controlled trial aims to compare manual dexterity and strength between a group undergoing a contralateral manual dexterity training program and a no-intervention control group in healthy, physically inactive individuals subjected to an induced upper-limb disuse model.
Cross-education of skill offers promising opportunities for the rehabilitation of upper-limb musculoskeletal injuries. An approach based on contralateral manual dexterity training could accelerate functional recovery, reduce motor skill loss during periods of immobilization, and optimize conventional rehabilitation protocols. However, controlled studies are needed to analyze the efficacy of specific unilateral training protocols designed to maximize cross-education before clinical translation. To date, no experimental studies have been published on healthy individuals subjected to upper-limb disuse models alongside contralateral skill training involving functional tasks. This cross-education effect could potentially prevent the loss of manual dexterity and strength that occurs during immobilization. For this research, a contralateral manual dexterity training protocol was developed based on the functional limitations commonly experienced by individuals with forearm and hand musculoskeletal injuries (e.g., distal radius fractures, wrist sprains, carpal tunnel syndrome, and tendinopathies). Additionally, the protocol incorporates characteristics from training programs that have demonstrated the greatest cross-education effect.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
34
The subjects in the experimental group will perform contralateral manual dexterity training focused on moving cylinders of 0.5, 1 or 1.5 kilos with grips and movements in different planes on a gridded board. Participants will have to develop different grips and place the cylinders in the quadrants indicated on a smartphone screen.
UCT, Facultad de ciencias de la Salud
Temuco, Araucania, Chile
Fine Manual Dexterity
Fine manual dexterity will be assessed using the Functional Dexterity test (FDT). Using a stopwatch, the evaluator records the total time in seconds that the participant takes to complete the task.
Time frame: Baseline and day 7
Force control
In a seated position with the elbow flexed, participants will perform isometric contractions to reach a target torque guided by real-time visual feedback. The accuracy of maintaining these contractions in the wrist flexor and extensor muscles will be assessed using a Humac Norm isokinetic dynamometer (Computer Sports Medicine, Inc., Stoughton, MA, USA). Participants will perform a continuous 60-second isometric contraction exercise. During this period, participants will adjust their force level to between 10% and 30% of their maximum voluntary contraction (MVC) at 10-second intervals. Three attempts will be performed per limb. The Root Mean Square Error (RMSE) will be recorded.
Time frame: Baseline and day 7
Gross Manual Dexterity
This gross manual dexterity will be assessed using the same task performed during the experimental group's contralateral manual dexterity training. Specifically, participants will complete 15 trials, moving cylinders of varying weights across a gridded board following a sequence displayed on a smartphone. The time required to complete these 15 trials will be recorded.
Time frame: Baseline and day 7
Handgrip strength
Maximum lumbrical and cylindrical grip strength will be assessed using a Jamar Plus+ digital hand dynamometer. The highest value from three attempts will be recorded for each assessment
Time frame: Baseline and day 7
Joint Position Sense Test
Proprioception: Wrist flexion-extension joint position sense will be assessed using the Joint Position Sense Test (JPST). All measurements will be conducted with a Humac Norm isokinetic dynamometer (Computer Sports Medicine, Inc., Stoughton, MA, USA). Three attempts will be made per limb. The absolute error (difference in degrees between 30° and the angle achieved during the test) will be recorded.
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Time frame: Baseline and day 7
Left/right judgment
Left/right judgment will be assessed using the Recognise™ application (Noigroup, Adelaide, Australia). Performance on the laterality judgment task was quantified using the Inverse Efficiency Score (IES), calculated as the average reaction time of correct responses divided by the proportion of correct responses (IES = RT / PC). 3 blocks of 20 images (60 images total). Maximum exposure time: 5 seconds per image.
Time frame: Baseline and day 7