Background: Manual therapy is commonly used by clinicians to improve blood flow and tissue fiber orientation. Hypothesis/Purpose: Using diagnostic ultrasound, the purpose of the study was to examine how the application of Positional Release Therapy (PRT), instrumented assisted soft tissue mobilization (IASTM), therapeutic ultrasound (US) and a combination of all three, affect lateral elbow immediate blood flow and tissue fiber alignment. Study Design: Controlled laboratory study. Methods: Twenty-five participants (26.0 ± 4.5 years; 69.3 ± 4.3 cm; 81.8 ± 16.9 kg) received PRT =13, US =12, IASTM =13, and a combination treatment = 12. Results: Blood flow was significantly higher following PRT (691.54 ± 1237.16 mm2) compared to IASTM (18.73 ± 227.10 mm²) (p=0.050; ES=0.073 (0.16-1.5) and US (-10.09 ± 479.26 mm²) (p=0.042; ES=0.72 (-0.03-1.29), but no different from the combination intervention (627.64 ± 820.22 mm²) (p=0.849). Seventy-five percent of elbows in the PRT intervention showed improvement in blood flow, 54% in the IASTM group, 45% in US, and 73% in the combination group. Tissue fiber alignment was significantly better following IASTM (-5756.00 ± 8156.19 mm²) compared to PRT (-1552.54 ± 3896.58 mm²) (p=0.042; ES=0.66 (-0.01 – 1.31), but no difference was demonstrated among the other interventions (p>0.066). All elbows (100%) that received IASTM showed improved tissue orientation, 77% in the PRT group, 64% in US and 64% in the combination group. Conclusion: Manual therapy, particularly PRT and IASTM, seem to be better at increasing blood flow and muscle fiber orientation, respectively. Level of Evidence: II.

Lateral epicondylalgia, Tennis elbow, Myofascial release, Perfusion