Electromyographic analysis of lower extremity muscle activities during modified squat exercise: Preliminary study

The squat is a movement that keeps the knee angle at 90° while keeping the weight of the one's shoulder to the shoulder width and maintaining equal weight load on the left and right legs. However, sufficient muscle activation of the lower limb is necessary to maintain a knee angle of 90 degrees. Thus, this study has been conducted to confirm the possibility that a modified squat exercise compared to traditional squat exercise can be recommended for elderly or patients. Two healthy adult males participated in this study. They performed a traditional squat exercise and a modified squat exercise. The modified squat exercise was performed in a general squat exercise posture while keeping the knee at 90 degrees and extending the hip joint with leaning the ball behind the back (supine position). The muscle activity of rectus femoris, vastus medialis, vastus lateralis, and gastrocnemius during exercises was measured by surface electromyography. As a result of this study, it was found that muscle activities were less in the right and left rectus femoris, vastus lateralis, vastus medialis during the modified squat exercise compared to the traditional squat exercise. The results showed that the muscle strength of the lower limb was activated to less than 50% compared with the traditional squat exercise during the modified squat exercise. These results may be used as an effective rehabilitation method for patients with weak muscles in the lower limb

Analysis of trunk and lower extremity electromyographic activity in horizontal whole-body vibration

Whole-Body Vibration (WBV) has been extensively investigated as a widely used training tool. However, previous studies mostly applied the WBV on synchronous or side alternating vibration platform devices. The present study was aimed to investigate the electromyographic activity of trunk and lower-extremity muscles as one stands on a flat floor, and during horizontal whole-body vibration (WBV). This was a comparative cross-sectional study. Sixteen healthy adults participated in the study. The electromyographic activity of the trunk and lower extremity muscles was collected while the participants stood on either a flat floor or a WBV device moving horizontally. Electromyography (EMG) was used to record the activity of trunk and lower extremity muscles (erector spinae, rectus abdominalis, rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius). The rectus femoris, tibialis anterior, and gastrocnemius muscles showed significantly higher muscle activation on the horizontal WBV device than on the flat floor (p<0.05). In particular, the electromyographic activity of Lt. rectus femoris (23.0 vs 14.3), Rt. rectus femoris (32.7 vs 15.1), Lt. tibiailis anterior (19.0 vs 9.8) Rt. tibiailis anterior (17.8 vs 7.9), and of the Lt. gastrocnemius (41.5 vs 15.7), Rt. gastrocnemius (32.7 vs 13.0) increased on the horizontal WBV device than on the flat floor. The muscle activity of the rectus femoris, tibialis anterior, and gastrocnemius muscles proved to be higher when the participants stood on the WBV device vibrating in a horizontal direction than on the flat floor. Further studies need to investigate the clinical applicability of horizontal WBV

Comparison of lower limb muscle activation according to horizontal whole-body vibration frequency and knee angle

Whole-body vibration refers to an exercise that stimulates the muscles, using a vibration with an amplitude and power, however, there are few studies that have dealt with fundamental questions such as optimal frequency or body position. This study aims to compare lower limb activation, according to horizontal whole-body vibration frequency and knee flexion angle, in healthy adults. Using 18 healthy adults aged 21–30, this study measured and analysed the activities of the vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GCM) muscles, for different horizontal whole-body vibration frequencies (0 Hz, 2 Hz, and 4 Hz) and knee flexion angles (0°, 30°, and 60°), using surface electromyography (sEMG). There was a statistically significant increase in lower limb muscle activation according to horizontal whole-body vibration frequency and knee flexion angle: comparing muscle activation with frequency, the muscle activation of VL, BF, TA, and GCM increased with increase in frequency (p<0.05). The muscle activation of VL and TA increased with increase in knee flexion angle (p<0.05). In this study, it was observed that for whole-body vibration provided in a horizontal direction, larger the frequency and higher the knee flexion angle, greater the lower limb activation

A novel one arm motorized walker for hemiplegic stroke survivors: a feasibility study

Abstract Background A hemiplegic stroke survivor with a moderate to severe gait disturbance may have difficulty walking using a one-arm walker. This study aimed to test the safety and feasibility of a prototype one-arm motorized walker that uses a power-driven device to provide gait assistance to hemiplegic stroke survivors with moderate to severe gait disturbances. Methods A one-arm motorized walker with a power-driven device was developed and tested with respect to 10 distinct variables, including weight, degrees of freedom, handle, handle substitution function, two-sided use function, variable handle height, redirecting function, electric moving parts through the handle control, brake function using the handle control, folding chairs, and design stability. Its safety and feasibility were tested in 19 hemiplegic stroke individuals using the Likert scale and a simple interview. Results The walker consists of a frame platform including a handle, electric motor for driving, one wheel for driving, two wheels for turning, unlocking sensor, driving button, and turning buttons. The walker is programmed so that a touch sensor in the handle can unlock the locking system. Furthermore, it is programmed so that a user can propel it by pushing the handle downward or pressing a button and can control directions for turning right or left by pressing buttons. Safety and performance testing was achieved for 10 separate variables, and a Likert scale score of 3.5 of 5 was recorded. Conclusion This walker’s novel design was developed for hemiplegic stroke survivors with moderate to severe gait disturbances. Our findings indicate that the walker is both safe and feasible for providing walking assistance to hemiplegic stroke survivors and establish the potential advantages of the one-arm motorized walker