Sample size
spastic diplegia CP, knee extensors, stroke, spastic musculature, neuromuscular disease, pain, quadriceps femoris, MVIC, muscle fatigue, knee joint pain
STROKE, NEUROMUSCULAR DISEASE
Based on the previous studies by Yanying Liu and Haiping Yang (2019) indicating that the blood lactate levels pre-exercise in the placebo group were 2.26 ± 1.3 mmol/L and increased after exercise to 14.93 ± 3.0 mmol/L, while in the laser group, it was 2.37 ± 1.1 pre-exercise and increased after exercise to 12.61 ± 3.2 mmol/L to detect the difference between groups with a power of 80% and a level of significance of 5% with an effect size of 0.25, a minimum sample size of 36 participants will be needed (i.e., 18 participants in each group), and 10% will be added to compensate for possible losses; therefore, the total sample size will be 40 participants (20 participants for each group). The sample size was calculated by G*Power (version 3.1.9.2; Germany) [So in our study, 40 participants (20 participants for each group) were studied. We examined the effect of low-level laser on muscle power, muscle fatigue, and child’s performance. We have used visual analog scale to test the level of pain (MVIC) and to measure the muscle power in children with neuromuscular disease and blood lactate level.After 1-month follow-up using low-level therapy in group A, it was observed that the visual analog scale showed that there is a decrease in the level of and were evaluated before treatment and after 1 month and the child performs the exercises much easier comparing to group B. In agreement of our results, there was a study in 2019 demonstrated that low-level laser therapy when applied to the quadriceps muscle was effective in reducing knee joint pain, increasing muscle power, and consequently improving walking speed [The muscle power of the quadriceps muscle and dorsiflexors of the foot for bilateral lower limbs was objectively assessed by the MVIC test. It was noted that during physical therapy sessions, children’s muscle fatigue had been delayed besides their muscle power had increased. We compared between the muscle power of the child before and after 1-month follow-up. According to the MVIC measurements, it was observed that there is an increase in muscle power and decrease in muscle fatigue of both groups more in laser group. A similar study was done in 2007 on spastic diplegia CP children; they used physiotherapy on quadriceps and triceps surae, using MVIC for evaluation, and they found that there was a greater increase in normalized force production for both quadriceps femoris and triceps surae and an increase in walking speed after training [Also, our results were in agreement with a study in 2010; their findings were consistent with the observed changes in biochemical markers related to skeletal muscle recovery and the decrease in muscle fatigue [Furthermore, we found that serum lactate levels decrease in the laser group, and this was in agreement with the study in 2015, which showed a reduction in blood lactate and increased time of onset of muscle fatigue after low-level laser therapy was applied to the spastic musculature of knee extensors in individuals after a stroke [