Repetitive shock wave therapy improves muscular microcirculation

Background Extracorporeal shock wave therapy (ESWT) is mainly applied in tendon as well as bone problems based on stem-cell activation and healing acceleration. The effect of ESWT on muscle tissue is much less understood to date. However, from a clinical perspective, muscle injuries are of distinct interest especially in elite athletes such as soccer players. Material and methods A total of 26 rats were randomized into two groups. Group A received a single application of high-energetic focused ESWT (0.3 mJ/mm², 4 Hz, 1000 impulses, 10 J), whereas group B underwent the same procedure every 10 min for three sessions (3 × 0.3 mJ/mm², 4 Hz, 3 × 1000 impulses, totaling 30 J). Blood flow at a depth of 8 mm was measured continuously and noninvasively by a combined Laser-Doppler-Imaging and photospectrometric technique (Oxygen-to-see, O2C, LEA Medizintechnik, Germany). Results One minute after the application of high-energy ESWT blood flow in group A increased by 16.5% (P = 0.007). Thereafter, it decreased from minute 2 after application and remained significantly unchanged to baseline value until the end of the measuring period at 50 min (P = 0.550). Group B showed a similar significant increase in blood flow of 16.4% (P = 0.049) and a decrease afterward, too. After the second focused ESWT blood flow was boosted to 26.6% (P = 0.004), remaining significantly elevated until the third application was initiated. Muscular blood flow was increased to 29.8% after the third focused ESWT (P < 0.001), remaining significantly increased for another 10 min. Conclusions Focused ESWT enhances blood flow in the muscle of rats. Moreover, repetitive ESWT extended this beneficial effect.