Velocity-based-training Frequency Can Differentially Affect Muscle Quality Changes In Persons With Parkinson’s Disease

Velocity-based training (VBT) utilizes changes in velocity rather than load to dictate progressions. No study has examined the dose-response mechanism of VBT on changes in echo intensity (EI) in people with Parkinson’s disease (PD). PURPOSE: Changes in EI (as measures of muscle quality) in the left and right rectus femoris (RF) and vastus lateralis (VL) muscles were analyzed following 2 separate training periods. Group1 trained for 2 days per week for 8 weeks and Group2 trained for 3 days per week for 8 weeks. Both conditions used a 30% velocity threshold protocol. METHODS: EI was measured using ImageJ software on images taken via B-mode ultrasound of the left and right RF and VL. Training frequency was also calculated for each subject. RESULTS: A one-way ANOVA was used to detect significant differences in training frequency. Mixed ANOVAs were used to detect main effects and interactions in EI. Results are reported as mean difference ± standard error (Mdiff ± SE), 95% confidence interval, and p-values. A significant difference in training frequency was observed between groups (F(1,16) = 48.818, p < .001). Group1 completed (mean ± SD): 13.4 ± 1.2 days, while Group2 completed: 18.7 ± 1.9 days. Significant time effects were seen for EI in the left RF, and both VL muscles. Pairwise comparisons showed significant decreases for the left RF (-8.5 ± 3.2; -15.2, -1.8, p = .017), right RF (-9.7 ± 3.5; -17.1, -2.3, p = .013), and the right VL ( -15.7 ± 3.8; -23.8, -7.6, p = < .001). Additionally, a group x time interaction was observed for EI in the right VL (F(1,16) = 5.072, p = .039). Pairwise comparisons showed a significant improvement for Group2 only (Mdiff ± SE = -24.315 ± 5.416, p = < .001). CONCLUSION: Results indicate that VBT is an effective training modality for inducing positive changes in muscle quality for individuals with PD. Further, either a greater training frequency or longer training period may yield superior improvements.