Effects of High-Speed Power Training on Neuromuscular and Gait Functions in Frail Elderly with Mild Cognitive Impairment Despite Blunted Executive Functions: A Randomized Controlled Trial.

BACKGROUND Physical frailty and impaired executive function of the brain show similar pathophysiology. Both of these factors lead to dysfunction of neuromuscular and abilities in elderly. High-speed power training (HSPT) has been determined to have positive effects on neuromuscular function and gait performance, as well as executive function in the elderly. OBJECTIVES The purpose of this study was to investigate the effects of 8-week HSPT on neuromuscular, gait and executive functions in frail elderly with mild cognitive impairment (MCI). DESIGN, SETTING AND PARTICIPANTS We performed a randomized controlled trial of frail elderly from community and medical center in republic of Korea. Forty-two physically frail elderly with MCI were randomly allocated to control (n=22, age=74.22±4.46) and intervention groups (n=18, age=73.77±4.64). The intervention group was subjected to HSPT, 3 times weekly for 8 weeks. MEASUREMENTS Isometric contraction of knee extension and flexion with electromyography (EMG) was measured to determine the neuromuscular function such as knee extensor strength, rate of torque development, movement time, pre-motor time, motor time, rate of EMG rise, and hamstrings antagonist co-activation. Additionally, the 4.44-meter gait and timed up-and-go (TUG) test were administered to assess gait performance. A frontal assessment battery was measured in this study. RESULTS The 8-week HSPT regimen improved the knee extensor strength from 1.13±0.08 to 1.25±0.07 (p<0.05), the 200-ms RTD from 3.01±0.3 to 3.55±0.24 (p<0.05) and the rate of EMG rise from 166.48±13.31 to 197.94±11.51 (p<0.05), whereas the movement time and motor time were statistically decreased from 921.69±40.10 to 799.51±72.84, and 271.40±19.29 to 181.15±38.08 (p<0.05), respectively. The 4.44-m gait speed and TUG significantly decreased from 6.39±0.25 to 5.5±0.24, and 11.05±0.53 to 9.17±0.43 respectively (p<0.05). CONCLUSION The findings of this study suggest the favorable effects of 8-week HSPT on the neuromuscular function and the gait performance in the frail elderly with MCI without increase in the executive function.