Laser therapy is one of the most advanced and effective non-invasive methods in physiotherapy, which is used to reduce pain, accelerate tissue repair and improve the performance of patients with musculoskeletal problems. This treatment method, which is also known as "photomodulation", affects skin receptors by shining light on the surface of the skin. This effect ultimately reduces pain and activates secondary receptors in different areas of the brain, including the cortex. #### Selection of low power or high power laser Choosing the type of laser, i.e. low-power or high-power laser, is determined in physiotherapy sessions depending on the depth of penetration, the duration of radiation and the amount of energy required. This choice is usually made by the physiotherapist after a detailed assessment of the patient's condition. Low-power laser is used to treat more superficial problems that require more time to achieve better results, while high-power laser is recommended for problems with deeper penetration and needing faster treatment. A low-power laser, with lower energy, is usually used to treat superficial areas such as skin or soft tissue injuries. These lasers are suitable for relieving chronic pain and increasing local blood circulation. On the other hand, high-power laser with greater penetration depth has the ability to affect muscles and joints and provides more tangible results in a shorter time. Therefore, this type of laser is very effective for cases that require faster recovery of range of motion, reduction of severe pain or repair of deep tissues such as tendons and muscles. #### The mechanism of laser effect on the body Laser therapy is particularly important in physiotherapy due to its ability to stimulate cell changes. One of the most important effects of laser is increasing energy in cells. This energy works in a similar way to the process of photosynthesis in plants. By penetrating the cells, laser light increases their energy and improves cell function. As a result, the tissue repair process is accelerated and inflammation is reduced. In addition, laser radiation also affects the blood circulation system and increases blood flow in the affected area. This process not only helps in faster recovery, but also by strengthening the immune system, it helps the body to deal with harmful factors. #### The importance of careful assessment and examination One of the important points in laser therapy is the careful evaluation and examination of the patient by the physiotherapist. Each patient has his own needs, and the amount of energy and the type of laser should be determined based on these needs. This evaluation includes examining the intensity of pain, the location of the injury, the general health status of the patient and other related factors. In many cases, hand-held (manual) lasers allow the physical therapist to make finer adjustments, resulting in greater and faster recovery. #### Powerful laser effects A high-power laser with a greater penetration depth, usually in a shorter period of time than a low-power laser, leaves significant effects in improving the range of motion, reducing pain, and eliminating disability. This type of laser is a good choice for patients who suffer from severe pain and chronic musculoskeletal problems. The ability of high power laser to repair tissues faster and reduce local inflammation has made it one of the main tools in physiotherapy treatment. #### Clinical applications of laser therapy In the "Tavan Novin" specialized physiotherapy center, under the supervision of physiotherapist Noushin Alvandian, low-power and high-power lasers are used professionally. After accurate diagnosis by specialists, in addition to the use of therapeutic exercises (occupational therapy), laser therapy is also used to accelerate the recovery process of patients. This method is especially effective in treating shoulder, knee, neck and back pain, and numerous researches have confirmed its positive effects. #### The results of research on the effectiveness of lasers Research has shown that the use of lasers in the treatment of musculoskeletal problems, especially in cases such as shoulder, knee, neck and back pain, has very positive results. For example, in the treatment of chronic neck pain, laser therapy significantly helps to reduce pain and increase range of motion. Also, for patients suffering from knee arthritis, this method can help reduce inflammation and improve joint function. In general, laser therapy is used as a safe and effective method in physiotherapy treatments for a wide range of musculoskeletal problems and can significantly improve the quality of life of patients.