Electromyography

Background and Purpose: Increasing participation in sports activities has increased the incidence of sports injuries. Considering the short and long term complications of sports injuries, the need to prevent them is one of the most important goals. The purpose of this study was to evaluate the effects of ankle bracing on the ankle plantar flexor muscles activity in different foot position during drop landing with and without fatigue. Method: Fourteen female college athletes participated in this study. Five models of 5 and 10 degrees medial, lateral and normal wedged insoles were used to simulate the position of the feet on the ground at the wrong landing technique. The Medial Gastrocnemius (MG) and Peroneus Longus (PL) muscles activity 100 ms before and 100ms after landing in different foot position before and after muscles fatigue with and without ankle bracing was recorded with surface electromyography. Repeated measures ANOVA was used for statistical analysis (p≤0.05). Results: The results showed that the effect of time on the activity of MG and PL muscles in landing with brace was significant, so that the MG muscle before landing and PL muscle after landing had a higher activity in both times before and after fatigue (p≤0.001). The activity of this muscles was not significant when using the ankle brace during landing in different positions (p˃0.05). Conclusions: According to the results of this study, lace-up brace can help to increase muscles activity when they were fatigue, while the using of brace does not affect muscle activity when landing perform in different positions without fatigue. According to the results, In the case of a suggestion to use brace for athletes, all aspects of using this equipment should be considered.

Introduction: This study aimed to investigate the onset time and the electromyographic activity level of the selected lower limb muscles in the active and inactive old women.Materials and Methods: In this case-control study, 28 old women with a Mean±SD age of 61.07±0.88 years were selected in the inactive (15 people) and active (13 people) groups. The electrical activity of the selected muscles of the lower limbs was collected by the EMG device in a stair down movement. Results: The onset time of tibialis anterior, vastus lateralis, and biceps femoris muscles are faster in the active group (p <0.05). Besides, the activity level of the rectus femoris muscle in the interval of 100 ms before the initial contact and the ratio of the vastus medialis muscle to the biceps femoris muscle was significantly lower (p <0.05) in the active group.Conclusion: It seems that the muscles of the lower limbs in the group of women with regular physical activity are activated faster than the inactive group and the decrease in the activity of the rectus femoris muscle and the ratio of the vastus medialis to the biceps femoris muscle in the active women may be accompanied by fatigue and reduced intra-articular forces. Therefore, it is recommended that old women participate in regular and active exercise programs to improve their onset times of muscle activity.

Background: Low back pain is a common musculoskeletal condition that can impact a person's ability to walk and move comfortably. Pronated foot posture has been suggested as a potential contributor to low back pain, and this study examines its impact on muscle activity during gait in individuals with low back pain. Aim: This study aimed to investigate whether pronated foot alters the activity timing of trunk and lower limb muscles during gait in low back pain patients. Materials and Methods: The sample of this study included 32 men with low back pain and pronated foot. Participants were divided into control (n=15, with foot pronated only) and experimental (n=17, with both low back pain and foot pronated) groups. The experimental group did resistance training with Thera-band for 12 weeks, 3 sessions per week. A wireless electromyography system with 9 pairs of bipolar surface electrodes was used to record the electromyography activity timing of back and lower limb muscles (sample rate: 2000 Hz). Two-way ANOVA was used for statistical analysis. Results: Significant between-group differences were found at baseline onset of EMG activity timing for gastrocnemious medialis ( P <0.001), gluteus medius ( P <0.001) and erector spinae at 3rd lumbar vertebral level ( P =0.001) muscles. Results indicated significant main effects of “Time” for erector spinae at 3rd lumbar vertebral level offset ( P =0.023), significant main effects of “group” for tibialis anterior offset ( P = 0.039) and for erector spinae at 3rd lumbar vertebral level offset ( P = 0.010). Conclusion: The selected training program changed the timing of erector spinae at 3rd lumbar vertebral level in older adults with both low back pain and pronated feet during walking.

Background : Cold sprays (CS) are widely used in sport competitions as an effective, simple, and high available treatment. Aim: The aim of present study was to investigate immediate and longtime effects of CS application onto the knee joint anterior-medial area of dominant leg on timing and activation pattern of selected muscles during one-leg landing. Materials and Methods: Thirty (15 control and 15 experimental) able-bodied male participated in this study. Electromyography activity of vastus medialis, rectus femoris, vastus lateralis, biceps femoris, semiendineus and medial gastrocnemius were recorded during one-leg landing tests (with dominant leg) for each of three conditions including before CS application (pre-test), immediately after (post-test 1), and 20 min later (post-test 2). To determine the effect of group and time on each dependent variable, three independent 2×2 multivariate repeated measures analyses of variance were performed (α < 0.05). Results : The results showed following trends rather than significant differences: the muscles in the experimental group had lower activity level and later onset immediately after CS application compared to before application, and they had higher activity level and sooner onset after 20 min from removing CScompared to immediate application. No significant interaction was found for normalized peak activation and time to peak activation ( P > 0.05). However, decrease in skin temperature after cold spray application was observed. Conclusion : These results show short-time cold application, which is so practical after many injuries for returning athletes to sport environment, may not predispose individuals to risk of re-injury or failed landing mechanism.