Velocity-Based-Training Frequency Impacts Changes in Muscle Morphology, Neuromuscular Performance, and Functional Capability in Persons With Parkinson's Disease.

Velocity-based training (VBT) positively impacts muscle morphology and performance in persons with Parkinson's disease (PD); however, optimal training frequencies for VBT in patients with PD remain undetermined. Changes in ultrasound-determined muscle thickness (MT) and echo intensity (EI)-derived muscle quality of the rectus femoris (RF) and vastus lateralis (VL), neuromuscular performance, and functional capacity were examined following 2 VBT frequencies (2-3 d·wk^-1) using 30% velocity loss thresholds for 12 weeks. Neuromuscular performance was assessed using computerized pneumatic resistance machines. For each variable, 2 (time) 3 2 (group) repeated-measures analyses of variance (ANOVA) were used to determine significant main effects and interactions. Significant time effects were seen for MT and EI of all muscles (p, 0.05). Muscle thickness improvements included right VL (RVL) (0.171 6 0.065 cm; p 5 0.019), left VL (LVL) (0.214 6 0.101 cm; p 5 0.049), right RF (RRF) (0.194 6 0.077 cm; p 5 0.023), and left RF (LRF) (0.318 6 0.109 cm; p 5 0.010). For EI, improvements occurred in RVL (218.688 6 3.600; p5,0.001), LVL (210.959 6 4.894; p 5 0.040), RRF (29.516 6 3.537; p 5 0.016), and LRF (29.018 6 3.444; p 5 0.019). Time effects were seen for leg-press 1-repetition maximum and peak power (p, 0.01) and habitual walking speed (p 5 0.022), with a group by time interaction for maximal gait speed favoring the 3 d·wk^-1 condition (δ0.15 m·s21, p 5 0.002). The results indicate that VBT at 2 or 3 d·wk^-1 can significantly improve muscle morphology, neuromuscular performance, and functional capability in patients with PD; however, improvements in maximal gait speed require 3 d·wk21. These findings provide flexibility when developing exercise prescriptions for patients with PD. [ABSTRACT FROM AUTHOR]