London: Sending low-frequency acoustic shock waves to injured muscles could speed up the healing process in the tissues, says an interesting study. The Extracorporeal Shock Wave Therapy (ESWT) works by mechanically stimulating the tissue, which prompts stem cells to kick-start repair work. "Our study indicates that shock waves increase the levels of chemical signalling factors in muscle tissue. These factors wake up "satellite" progenitor cells which gradually becomes new muscle fibres," said Angela Zissler, at the University of Salzburg in Austria. For injuries like ligament and tendon damage, applying the low-frequency shock waves in ESWT has already proved to be a promising technique. In the study, the team tested ESWT on rats and discovered that the procedure triggered muscle tissue to kick-start the self-healing process. ESWT has good potential as a non-invasive therapy complementing or supplementing existing recovery regimes, said the paper published in the journal Society for Experimental Biology. "This therapy only needs sessions of around 15 minutes, so easily complements traditional practices such as physiotherapy. Another bonus is that there are no side-effects to low-energy ESWT, unlike some other methods," Zissler explained. In an ESWT session, shock waves are applied on the patient's damaged area at a low frequency (roughly 1 pulse per second). These waves then focus a small amount of energy (less than 0.2 mJ/mm2) on the damaged area, without the need for using local anaesthetics. This technique could also help injured athletes to return to training and be able to compete more quickly than just with traditional methods, the researchers concluded.