Effects of Low Level Laser Therapy On Exercise Induced Muscle Damage in Wrist Flexors Of Untrained Young Adults.

Wrist flexors play a crucial role in hand function. This group of small muscles is of high importance in our day to day tasks like carrying heavy objects and for activities in which forceful and/or rapid wrist flexions are required. Apart from this, the wrist flexors have a distinctive neural control as compared to the other surrounding musculature.

Muscle exhaustion that is induced after eccentric exercise, can either be of acute onset or delayed onset. Exercise induced muscle soreness that persists for about 4 to 6 hours before it returns to pre-exercise level is termed as acute soreness. On the other hand, muscle soreness beginning at 8 to 24 hours after eccentric exercise, with peak level at 24 to 48 hours is known as delayed soreness. Delayed-Onset Muscle Soreness (DOMS) is a common neuromuscular condition characterized by increased sensitivity to pain that is apparent with unaccustomed or vigorous exercise, a day after performance. DOMS becomes evident about 6-8 hours after an intense exercise bout and peaks at approximately 24-72 hours post-exercise. During first few hours of intensive exercise metabolism get disturbed that leads to inefficient physical activity and performance. Prolonged metabolic disturbances and physical activity and performance impairment progressing to days ultimately induce tissue damage that we call as delayed-onset muscle soreness. Event that produces muscle soreness is suggested as a mechanical disruption of sarcomeres leading to swelling of injured muscle fibers thus initiating an inflammatory response leading to the excitement of nociceptors.

Exercise-induced muscle injury is similar in pathological change and pathogenic mechanism in humans and animals. Human beings and animals have shown parallel reactions to changes caused by muscle damage induced by eccentric exercises. The beginning of initial exercise-induced muscle damage may be draining but is pain free. Later on, after 8-24 hours of muscle damage initiation, the subsequent inflammation results in delayed onset of muscle soreness.

It has been assumed that whenever an un-habitual physical exercise is carried out by a person then muscle injury occurs. A high level of muscle injury is associated with eccentric activities. Muscle injury is more likely to occur in untrained individuals who start practicing exercise. Furthermore, incidence of muscle injury is more common with exercises involving eccentric activities. Loss of strength, muscle inflammation, high level of muscle proteins in blood and delayed onset of muscle soreness DOMS are considered to be the expected outcomes of muscle injury. Different electro-physical modalities are being used by Physical therapists. In many conditions, improved healing and functioning are achieved by the use of these electro-physical modalities. Some animal studies have also reported the positive role of Low-Level Laser Therapy, when used in optimal parameters of irradiations, in enhancing the muscle healing and decreasing inflammation. Increased amount and activity of mitochondria and increased cross-sectional area of muscle fiber is associated with training. Increased muscle mass and improved mitochondrial function result in shift in muscle fiber type composition, from type two B to type Two A, and an increase in local glycogen storage capability. These combined adaptations make specialized athletes chiefly different from untrained people.

Several studies performed on human and animals evidenced the action of Low-level Laser Therapy in achieving therapeutic and physiological effects involving improvement of muscle functioning through interaction with biological tissues. Decrease in muscle fatigue has been reported by several researchers with the application of Laser Therapy before exercises that induces fatigue while considerable functional enhancement has also been evidenced by some investigators with Laser application after performing fatigue inducing exercises. Therapeutic effect of LLLT may be explained by mechanisms involving improved microcirculation of tissue, anti-inflammatory effect, decreased oxidative stress and decrease in tissue ischemia.