Background: This study investigated quadriceps femoris muscle activity by comparing concentric and eccentric contractions with self-selective squat speed. Objectives: Study participants agreed in advance and included 30 male college students in their 20s without musculoskeletal system disease. Design: A randomized controlled trial. Methods: Participants who participated in this study agreed in advance and recruited 30 male college students in their 20s who had no disease with musculoskeletal system to conduct this study. When squatting at a self-selected speed, the subjects were evaluated using one-way ANOVA to compare concentric and eccentric contraction muscle activity. Results: There were significant differences between the rectus femoris, vastus medialis, and vastus lateralis regarding concentric contractions.contractions. There was a significant difference in vastus medialis but no significant difference between rectus femoris and vastus lateralis for eccentric contractions. Conclusion: During concentric contraction, all muscles and eccentric contractions indicated significant improvement in the vastus medialis. Therefore, to minimize knee joint injury and maximize efficient muscle activity, self-selected slow and moderate speeds based on self-selection speed when performing the sit-down motion during a squat and moderate speed with fast motions when performing the standing motion should be considered as high muscle activities.

Background: Elastic and non-elastic taping are widely used in clinical practice, but there are various methods of attachment. Objectives: To investigate the effect of the type and intensity of taping on the muscle strength and muscle endurance of healthy adults. Design: Experimental research. Methods: 38 healthy adults participated in this experiment. Before applying the taping to each participant, the muscle strength and endurance of the quadriceps femoris were measured. After applying three different taping intervention methods, muscle strength and muscle endurance changes were measured. Muscle strength and endurance were measured through CSMI. Repeated measures ANOVA was used for statistics on participant measurements. Results: All intervention methods influenced the muscle strength improvement of the quadriceps femoris. Elastic tape with 50% elasticity had a greater impact on muscle strength than 33% elastic tape and non-elastic tape, and secondly, elastic tape with 33% elasticity was effective, and non-elastic tape had the least impact. Muscle endurance improvement was affected by the order of 50% elasticity taping, 33% elasticity taping, and non-elastic taping. Conclusion: All three taping intervention methods showed significant effects on improving muscle strength and muscle endurance of the wide-legged quadruple muscles, but the best effect was to apply 50% elastic taping.

To develop effective training methods for strengthening a weakened quadriceps femoris muscle in hemiplegic patients, we examined the effects of maximal isometric contraction of the nonparalyzed knee joint on the electromyographic activities of the paralytic muscle. An electromyogram (EMG) was used to record the electromyographic activities of the paralytic quadriceps femoris muscle in 27 hemiplegic patients. The maximal isometric contraction was measured for each subject to normalize the electromyographic activities. The maximal isometric extension and flexion exercises were randomly conducted when the knee joint angles of the nonparalyzed knees were 0˚, 45˚, and 90˚. The patients were encouraged to maintain maximal isometric contractions in both knee joints during each measurement, and three measurements were taken. A one-minute rest interval was given between each measurement to minimize the effects of muscle fatigue. An average from the three values was taken as being the root mean square of the EMG and was recorded as being the maximal isometric contraction. The electromyographic activity obtained for each measurement was expressed as a percentage of the reference voluntary contraction, which was determined using the values obtained during the maximal isometric contraction. The results of this study are summarized as follows: First, when the knee joint angle of the nonparalyzed knee was 0˚, the electromyographic activities of the paralytic medial aspect of rectus femoris were related to measurement by a maximal isometric flexion exercise than by an extension exercise (p<.05). Second, when the knee joint angle of the nonparalyzed knee was 90˚, the electromyographic activities of the paralytic lateral aspect of rectus femoris were related to measurement by a maximal isometric flexion exercise than by an extension exercise (p<.05). The results show that myoelectrical activities of paralytic quardriceps were not related to measurement angles and exercise directions of the nonparalized knee joint. Studies on various indirect intervention to improve muscular strength of patients with nervous system disorders of the weakened muscle should be constantly conducted.

This study was designed to identify the effects of foot position on electromyographic (EMG) activity of the quadriceps femoris during maximum voluntary contraction (MVC) in standing. Twenty young adults who had not experienced any knee injuries were recruited. Their Q-angles were within a normal range. They were asked to stand in five different foot positions ( externally rotated, internally rotated, neutral, plantarflexed, and dorsiflexed foot position). The EMG activities of the vastus lateralis (VL), rectus femoris (RF), and vastus medialis oblique (VMO) were recorded in standing by surface electrodes and normalized by MVC EMG values derived from manual muscle test. The normalized EMG activity levels (%MVC EMG) of muscles in the five foot positions were compared using repeated measures ANOVA. The EMG activity levels of the VL, RF, and VMO were the highest when foot was externally rotated. The EMG activity levels of the VL and RF were significantly different among the foot positions (p<.05). However, EMG activity levels of the VL, RF, VMO, and VMO/VL ratio did not show significant differences in each foot position (p> .05). The results suggest that the quadriceps femoris may be effectively activated by performing MVC at an externally rotated foot position. Therefore, the externally rotated foot position can be considered as an effective foot position for quadriceps femoris strengthening exercise. Further studies are needed to identify whether there are differences in the effects of foot position on muscle strength after MVC exercise of quadriceps femoris in standing.

The purpose of this study was to compare the integrated electromyographic activity ratios of vastus lateralis(VL); rectus femoris lateral portion (RFL); rectus femoris medial portion(RFM); and vastus medialis(VM) muscles of 30 healthy subjects under three proprioceptive neuromuscular facilitation(PNF) techniques. Each subject was randomly assigned to one of 3 PNF techniques groups : slow reversal(SR), slow reversal hold(SRH) and rhythmic stabilization (RS). Each person was positioned in supine with the right hip flexed to and the knee fully extended and received a total of 6 sessions. Each technique was applied to the right lower extremity in two diagonal patterns while electrical activity was monitored from the ipsilateral muscles VL, RFL, RFM, and VM, respectively. Comparison of normalized mean EMG magnitudes from VL, VM showed that RS demonstrated significantly greater activity than that of SR or SRH and that RFL and RFM did not demonstrate any greater relative EMG activity with the three PNF techniques than did VL or VM.

The purpose of this study was to determine whether the vastus medialis oblique muscle(VMO) had greater electrical activity than the vastus lateralis muscle(VL) when hip adduction and knee extension exercise were performed. Electrical activity of the VMO and VL was measured on 42 healthy subjects (28 men, 14 women) during maximal voluntary isometric contractions of hip adduction and knee extension by an EMG-BIOFEEDBACK. The results showed that the electromyographic activity of the VMO was significantly greater than that of the VL during the hip adduction exercise. Differences noted with knee extension by performing hip adduction exercises. Isometric hip adduction exercises, therefore, may be advisable in the treatment of patients with patellofemoral pain.