Strength training improves the tri-digit finger-pinch force control of older adults

Objective: To investigate the effect of unilateral upper-limb strength training on the finger-pinch force control of older men. Design: Pretest and post-test 6-week intervention study. Setting: Exercise science research laboratory. Participants: Eleven neurologically fit older men (age range, 70-80y). Intervention: The strength training group (n=7) trained twice a week for 6 weeks, performing dumbbell bicep curls, wrist flexions, and wrists extensions, while the control group subjects (n=4) maintained their normal activities. Main Outcome Measures: Changes in force variability, targeting error, peak power frequency, proportional power, sample entropy, digit force sharing, and coupling relations were assessed during a series of finger-pinch tasks. These tasks involved maintaining a constant or sinusoidal force output at 20% and 40% of each subject's maximum voluntary contraction. All participants performed the finger-pinch tasks with both the preferred and nonpreferred limbs. Results: Analysis of covariance for between-group change scores indicated that the strength training group (trained limb) experienced significantly greater reductions in finger-pinch force variability and targeting error, as well as significantly greater increases in finger-pinch force, sample entropy, bicep curl, and wrist flexion strength than did the control group. Conclusions: A nonspecific upper-limb strength-training program may improve the finger-pinch force control of older men.