Comparison Of Lower Body Power Outputs To Muscle-ultrasound Morphology In Persons With Parkinson’S Disease

Velocity-based training (VBT) is a unique new resistance-training technique used by high-level athletes, which utilizes velocity thresholds rather than loads to dictate progressions. No study has examined the correlations between lower-body power and muscle-ultrasound measures before and after a period of VBT. PURPOSE: This secondary analysis examined the correlations between lower-body power and muscle morphology changes following a 10-week VBT study using 10% and 30% velocity thresholds in persons with PD. Subjects completed both power-testing and an ultrasound assessment before and after a training period. METHODS: Participants, recruited from a university population, residents of surrounding neighborhoods, and an existing phone-list, provided pretest and post-test data including leg press 1-repetition-maximum (1RM) and peak power (PP) at 40through 80% 1RM. Muscle thickness (MT), echo intensity (EI) and fascicle angle (FA) were measured with ImageJ software on images taken via B-mode ultrasound of the left and right rectus femoris (RF) and vastus lateralis (VL). RESULTS: Data from 17 subjects were used for the analysis. At pretest, significant correlations were observed between MT and PP at 40-80% 1RM in all muscles (all p < .05, r range .50 to .78) except at 70-80% 1RM in the right RF. FA was correlated to PP at 40-80% 1RM in the right VL (all p < .05, r range = .51 to .61), and EI in the right RF at 60% 1RM. (p < .05, r range = -.50 to -.58). At post-testing, significant correlations were observed between MT and PP at 40-80% 1RM in the right and left VL and left RF (all p < .05, r range = .56 to .79). Correlations were observed for FA in both VL muscles at 40-80% power (all p < .02, r range = .56 to .83). Significant correlations were also observed between EI in both VL muscles and PP muscles at 40-80% 1RM (all p < .05, r range .54 to .76), excluding 50% 1RM in the left VL. No significance was shown between FA and EI of the RF, and lower body power. CONCLUSIONS: Results indicate that improvements in lower body power-output following VBT may be due to changes in FA and EI, rather than MT alone.