ABSTRACT
Objective：This study aimed to examine the effects of kilohertz-frequency alternating current (KFAC) on muscle performance and adverse event in patients with neuromuscular skeletal disorders.Methods：A literature search was conducted in PubMed, PEDro, CINAHL, and Cochrane CENTRAL until September 2017. The reviewer extracted data on subject characteristics, intervention, target muscle, and outcome measures in accordance with the Cochrane Handbook.Results：The literature search yielded 1295 studies, and 3 studies met the inclusion criteria (n＝32；mean age：45.3 years). KFAC stimulation combined with land-based exercise was likely more effective in increasing the quadriceps femoris muscle strength than exercise alone in patients after total knee arthroplasty (TKA). However, KFAC was not superior to low-frequency pulsed current in increasing pedaling work in patients with spinal cord injury. No severe adverse event relevant to KFAC was reported in all 3 studies. The quality of evidence was very low according to the GRADE approach.Conclusion：Additional KFAC may be more effective than exercise alone in improving the quadriceps femoris muscle strength in patients after TKA without any severe adverse event. Further studies to investigate the effects of KFAC are warranted to increase the confidence for the effects of KFAC treatment.
ABSTRACT
The Q angle represents an estimate of the resultant force of the quadriceps on the patella and is a predictor of the lateral movement of the patella under dynamic conditions. The aim of the present study was to observe whether Isometric Quadriceps Activation (IQA) can decrease the Q angle and to identify people at high risk of patellar subluxation. Q angles were measured in 23 non impaired young women (22.9±2.3 years) in relaxed standing and during IQA. There was a significant decrease (4.65±2.74°) in the Q angle values for subjects with IQA as compared to subjects with measurements in relaxed standing Significance levels were set at P<0.05. The Q angle decreases with IQA which was highly significant (t=8.01, P<0.001). The result supports the view that an excessive Q angle may predispose women to greater lateral displacement of the patella during vigorous activities and sports in which the quadriceps muscle is stressed.
ABSTRACT
@#Objective To observe the effects of systems of progressive resistance exercise on lower limb extensors （quadriceps femoris） of stroke patients. Methods 89 stroke patients with weak lower limbs were randomly divided into progressive resistance exercise group (n=46) and control group (n=43), both receiving corresponding treatment for 4 weeks. They were assessed with Manual Muscle Test (MMT), integrated electromyogram (iEMG) and root mean square (RMS) of surface electromyography on quadriceps femoris before and after the treatment. Results The incidence of improvement with MMT was 94.3% in progressive resistance exercise group, and 63.8% in control group （P<0.01）. The iEMG and RMS of the exercise group was significantly higher than that of the control （P<0.01）. Conclusion The systems of progressive resistance exercise could improve the muscle strength of lower limbs extensors of stroke patients more effectively.
ABSTRACT
A study was conducted to determine the minimum quantity of leg exercise required to prevent disuse atrophy of the quadriceps femoris muscle during bed rest. The subjects were 10 normal young university students with a mean age of 21.1 years. First, analysis of rectified filtered electromyography (RFEMG) was performed on the rectus femoris and vastus medialis during walking with cadences of 100 steps/min and 150 steps/min. Then, the effects of straight leg raising (SLR), patella setting (PS), knee extension-flexion in a supine position (KEF) and knee extension in a sitting position (KE) were analysed for each muscle using the same method. Based on the value of RFEMG for each muscle during walking, the repetition number for each exercise was calculated. For the rectus femoris, the repetition number for each exercise corresponding to 10000 steps with a cadence of 100 steps/min was 289 for SLR, 466 for PS, 1255 for LEF and 1663 for KE. For the vastus medialis, the corresponding numbers were 1223, 381, 6367 and 2170, respectively. When the cadence increased to 150 steps/min, the repetition number of each exercise for each muscle also increased. These results indicate that high repetition exercise is recommendable to prevent disuse atrophy of the quadriceps femoris muscle. Therefore, the activity of patients should be increased to stimulate weakened muscles such as the quadriceps femoris during hospitalization.