Cross-education of Skill and Strength in Healthy People Subjected to an Upper-limb Disuse Model

Cross-education of Skill and Strength Through Contralateral Manual Dexterity Training in Healthy Young Adults Subjected to an Upper-limb Disuse Model: A Randomized Controlled Trial.

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.

Inclusion Criteria:

• Individuals will be eligible for inclusion if they are right-handed adults aged 18 to 35 years with a body mass index (BMI) between 18.5 and 30 kg/m².
• Individuals must be classified as physically inactive, defined as not meeting the World Health Organization criteria of at least 150 minutes of moderate-intensity physical activity or 75 minutes of vigorous-intensity physical activity per week.

Exclusion Criteria:

• Individuals who have engaged in physical training (e.g., any form of strength or aerobic exercise) or specific manual dexterity training within the past 6 months. - Individuals who regularly participate in artistic, occupational, or sporting activities requiring high levels of manual dexterity (e.g., musicians, gamers, craftspeople).
• Individuals with a history of orthopedic or traumatic injuries affecting either upper extremity. Individuals with pathologies or conditions that preclude safe training (e.g., uncontrolled hypertension, or visual, auditory, or cognitive impairments [for example, dyscalculia]).
• Individuals currently using nutritional supplements or medications that interfere with the regulation of skeletal muscle mass and strength (e.g., whey protein, creatine) or the central nervous system (e.g., antidepressants, anxiolytics, hypnotics).