Exercise effect on electromyographic activity of the vastus medialis oblique and vastus lateralis muscles

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 medial (internal) tibial rotation exercises were performed. Electrical activity of the VMO and VL was measured on 25 healthy subjects during maximal-effort isometric contractions of hip adduction and medial tibial rotation. 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 medial tibial rotation were not significant. The results suggest that the VMO may be selectively activated by performing hip adduction exercises. Resistive hip adduction exercises, therefore, may be advisable in the treatment of patients with lateral malalignment of the patella with accompanying pain or instability.     

Effects of visibility and types of the ground surface on the muscle activities of the vastus medialis oblique and vastus lateralis

[Purpose] The purpose of this study was to compare the effects of visibility and types of ground surface (stable and unstable) during the performance of squats on the muscle activities of the vastus medialis oblique (VMO) and vastus lateralis (VL). [Subjects and Methods] The subjects were 25 healthy adults in their 20s. They performed squats under four conditions: stable ground surface (SGS) with vision-allowed; unstable ground surface (UGS) with vision-allowed; SGS with vision-blocked; and UGS with vision-blocked. The different conditions were performed on different days. Surface electromyogram (EMG) values were recorded. [Results] The most significant difference in the activity of the VMO and VL was observed when the subjects performed squats on the UGS, with their vision blocked. [Conclusion] For the selective activation of the VMO, performing squats on an UGS was effective, and it was more effective when subjects’ vision was blocked.Key words: Vision, Unstable, VMO     

Activation of the vastus medialis oblique and vastus lateralis muscles in asymptomatic subjects during the sit-to-stand procedure

[Purpose] The purpose of this study was to examine the vastus medialis oblique to vastus lateralis ratio in two pelvic tilt positions while performing the sit-to-stand task. [Subjects and Methods] Activation of the vastus medialis oblique and the vastus lateralis muscles of 46 healthy subjects (25 males, 21 females) were recorded by surface electromyography during the STS task with anterior pelvic tilt (sit with thoracolumbar spine extended and pelvis in an anterior tilt) and neutral pelvic tilt (sit with thoracolumbar spine relaxed and pelvis in the neutral tilt position) positions. Changes in vastus medialis oblique, vastus lateralis activation and the vastus medialis oblique/vastus lateralis ratio were analyzed. [Results] Vastus medialis oblique and vastus lateralis muscle activation significantly increased in neutral pelvic tilt position, but the vastus medialis oblique/vastus lateralis ratio was not statistically different. [Conclusion] The sit-to-stand procedure with neutral pelvic tilt position increased activation of the vastus medialis oblique and vastus lateralis, usefully strengthening the quadriceps, but did not selectively activate the vastus medialis oblique muscle.Key words: Anterior pelvic tilt, Neutral pelvic tilt, Sit-to-stand task     

EMG activity of the vastus medialis oblique and the vastus lateralis in their role in patellar alignment

Using intramuscular electrodes the integrated electromyographic activity of the vastus medialis oblique and the vastus lateralis was examined in twenty normal females. The activity was recorded during the last thirty degrees of distal segment stabilized knee extension, when patellar subluxation commonly occurs. The electromyographic activity was normalized and expressed as a percentage of a maximal isometric contraction. Both muscles exhibited low levels of activity with no significant differences between the two. This study provides a quantitative method to assess whether muscular imbalance is present in patients with patellar subluxation.     

Effects of the slow speed-targeting squat exercise on the vastus medialis oblique/vastus lateralis muscle ratio

[Purpose] This study investigated the effects of the slow speed-targeting squat exercise on the vastus medialis oblique/vastus lateralis ratio. [Subjects] Ten asymptomatic men were recruited. [Methods] The EMG activities of the vastus medialis oblique and vastus lateralis muscles were recorded using surface electrodes. The subject performed the squat exercise under 3 different conditions. [Results] The vastus medialis oblique/vastus lateralis ratio in condition 2 (1.5 ± 0.7) was significantly higher than that in conditions 1 and 3 (1.0 ± 0.5, 1.1 ± 0.8, respectively) [Conclusion] Therefore, an effectively slow movement speed is recommended for selective strengthening of vastus medialis oblique using a slow speed-targeting device that provides biofeedback.Key words: Slow movement speed, Squat exercise, VMO     

The influence of weakness in the vastus medialis oblique muscle on the patellofemoral joint: an in vitro biomechanical study

OBJECTIVE: Investigation of the influence of weakness in the vastus medialis oblique muscle on patellar tracking. DESIGN: In vitro biomechanical study. BACKGROUND: Currently, the influence of weakness in the vastus medialis oblique muscle on patellar tracking has not been well understood. METHODS: Seven human cadaveric knees were used. The direction of loading forces in the rectus femoris/vastus intermedius, vastus medialis oblique, and the vastus lateralis muscles was decided by the muscle alignment of each cadaver knee measured at the time of dissection. The loads used were 60 N in the rectus femoris, 50 N in the vastus lateralis, and 40 N in the vastus medialis oblique, according to the ratio calculated from the cross-sectional study. The weakness of vastus medialis oblique was simulated at 30 N (75%), 20 N (50%), 10 N (25%), and 0 N (0%), and the patellar position was measured for each condition using a magnetic 3 Space Tracker System. The influence of weakness in the vastus medialis oblique muscle on patellar position was investigated with seven cadaver knees using a magnetic 3 Space Tracker System. RESULTS: At 0 degrees and 15 degrees of knee flexion, 75%, 50%, 25% and 0% of the normal vastus medialis oblique muscle led to a significant difference in lateral patellar shift compared to the normal (P<0.05). CONCLUSIONS: Weakness of the vastus medialis caused the patellar lateral shift at 0 degrees and 15 degrees of knee flexion. RELEVANCE: Weakness of the vastus medialis is thought to be an important factor causing patellar subluxation and dislocation. Understanding the relationship between the vastus medialis weakness and patellar tracking will be useful in diagnosis, treatment and prevention of patellar subluxation and dislocation.     

The effects of squatting with visual feedback on the muscle activation of the vastus medialis oblique and the vastus lateralis in young adults with an increased quadriceps angle

[Purpose] The purpose of this study was to identify the effects of performing squat exercises with visual feedback on the activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles in young adults with an increased quadriceps angle (Q-angle). [Subjects] This study used a motion analysis program (Dartfish, Switzerland) to select 20 young adults with an increased Q-angle, who were then divided into a squat group that received visual feedback (VSG, n=10) and a squat group that received no visual feedback (SG, n=10). [Methods] The intensity of exercises was increased every two weeks over a six-week exercise period in both groups. A visual marker was attached to the patella of the subjects in the VSG, and they then performed squat exercises with a maximum of 90° of knee flexion within a route marked on a mirror. The SG performed squat exercises with a maximum 90° of knee flexion without attaching a visual feedback device. [Results] Analysis of the muscle activation due to 90° squat exercises indicated that both groups had statistically significant increases in activation of the VL. The VSG exhibited statistically significant increases in activation of the VMO. [Conclusion] This study confirmed that squat exercises with visual feedback are effective in activation of the VMO and VL muscles. The findings are meaningful in terms of preventing the occurrence of patellofemoral pain.Key words: Q-angle, Visual feedback squat exercise, VMO     

Effects of bridge exercise on trunk core muscle activity with respect to sling height and hip joint abduction and adduction

[Purpose] This study evaluated the effects of bridge exercise on trunk core muscle activity with respect to sling height and hip joint abduction and adduction. [Subjects] Fifteen healthy adult males participated. [Methods] In the bridge exercise, the height of the sling was set low or high during hip joint abduction and adduction. Electromyography was used to compare the differences between the muscle activities of the transverse abdominis, rectus abdominis, and erector spinae muscles. [Results] The muscle activities of the transverse abdominis, rectus abdominis, and erector spinae were significantly higher in the high sling position. Furthermore, the activities of the transverse abdominis and erector spinae were significantly higher during hip joint adduction than abduction regardless of sling height. [Conclusion] A high sling height is the most effective intervention for increasing the muscle activities of the transverse abdominis and erector spinae muscles during hip joint adduction in a bridge exercise.Key words: Bridge exercise, Trunk core muscle, Sling     

The effect of hip abduction on the EMG activity of vastus medialis obliquus, vastus lateralis longus and vastus lateralis obliquus in healthy subjects

Study design  

Controlled laboratory study.     

Ultrasound investigation into the relationship between hip adduction and the patellofemoral joint

[Purpose] Patellofemoral pain (PFP) is a common musculoskeletal complaint. It has been suggested that hip adduction creates a load on the iliotibial band and causes lateral displacement of the patella (patella tilt). However, data gathered in a previous study were derived from a small sample of males, while the condition predominantly affects females. We assessed the relationship between hip adduction and patellar position with a larger sample size, including males and females. [Participants and Methods] Forty healthy, asymptomatic females and males (age 21.5 ± 1.3 years) were recruited. Their knees were passively flexed by 20°. Using ultrasound, the distance between the lateral edge of the patella and the lateral condyle of the femur was measured in the neutral position and at 20° adduction. [Results] Hip adduction produced a smaller patella-lateral femoral condyle measurement than in the neutral position. The mean difference in the patella-condyle distance between the neutral position and 20° hip adduction was 0.18 cm. No statistically significant difference was found between the right and left limbs, genders, Tegner scores, or BMI of the study participants. [Conclusion] The results of the study showed that hip adduction causes lateral displacement of the patella. Ultrasound is an effective means of assessing patella tilt.     

The effect of stretching exercises on the fibre angle of the vastus lateralis and vastus medialis oblique: an ultrasound study

[Purpose] To investigate the effects of a seven-week quadriceps stretching program on the muscle fibre orientation of the vastus medialis oblique and vastus lateralis in the lower limbs by ultrasound imaging. [Participants and Methods] Twenty-seven healthy, physically fit, asymptomatic females and males (age 21.5 ± 1.3, Tegner activity level score ≥4) were recruited. Their initial vastus medialis oblique and vastus lateralis fibre angles were determined using ultrasound. They then undertook a seven-week quadriceps stretching program, 3 sets of stretches to be performed on both lower limbs, 3 times a week on 3 separate days. One volunteer was assigned as an intra-rater control and did not take part in the stretching program. The vastus lateralis and vastus medialis oblique fibre angles were measured again on completion of the exercise regime. [Results] A statistically significant decrease in muscle fibre angle was observed in both the right and left vastus medialis oblique, and the right and left vastus lateralis. [Conclusion] A 7-week stretching program can result in a significant decrease in muscle fibre angle in both the vastus medialis oblique and the vastus lateralis. This can help in understanding the effects of prescribed stretching exercises on athletic patients with PFP.     

Effects of simulated vastus medialis strength variation on patellofemoral joint biomechanics in human cadaver knees

Selective strengthening of the vastus medialis (VM) muscle is a conservative treatment used to address some patellofemoral joint (PFJ) problems. The objective of this study was to examine the effects of varying VM strength on PFJ kinematics and contact pressures and areas. We tested five fresh-frozen cadaveric knees using a custom knee jig, which permits the simulation of physiologic quadriceps loading while also allowing the VM force to be varied. PFJ kinematics were measured with a magnetic tracking device. PFJ contact pressures and areas were measured with Fuji pressure-sensitive film. For PFJ kinematics, the change in the medial-lateral and superior-inferior translation was significant at 0% of VM strength and 150% of VM strength with respect to the 100% of VM strength condition (p < 0.05). Extreme changes in the VM force had a statistically significant effect on patellofemoral contact pressures (0% of VM strength (19 +/- 10%) and 150% of VM strength (17 +/- 3%) with respect to 100% of VM strength condition (p < 0.05)). No statistically significant differences were shown in the patellofemoral contact areas (p > 0.05). The functional range of VM strength is between 75% and 125% of total VM strength. The PFJ kinematics and contact pressures were not significantly influenced by VM strength except at extreme conditions (0% of VM strength or 150% of VM strength) in human cadaveric knees.     

The vastus medialis oblique:vastus lateralis electromyographic intensity ratio does not differ by gender in young participants without knee pathology

Objectives

To investigate whether there was a gender difference in the intensity of electromyographic (EMG) activity in vastus medialis oblique (VMO) relative to vastus lateralis (VL).

Design

A cross-sectional observational study measuring EMG activity during stepping down from a step and during straight leg raise exercises.

Setting

University campus laboratory.

Participants

Two groups of healthy participants were tested, one female (mean age 23.5 years, n = 15) and one male (mean age 23.5 years, n = 15).

Main outcome measures

Surface EMG activity (sampling rate 1000 Hz) was recorded from VMO and VL of the dominant limb during five repetitions of a step down activity and five repetitions of a straight leg raise exercise. The average intensity of the rectified and smoothed EMG activity from each activity was normalised to that elicited in a maximal quadriceps setting exercise. The ratio of normalised VMO:VL EMG intensity levels was calculated.

Results

The median difference in the VMO:VL ratio between the groups was 0.11 [approximate 95% confidence interval (CI) −0.62 to 1.00] during step down and −0.07 (approximate 95% CI −0.26 to 0.20) during straight leg raise. Using Mann Whitney U-tests, these differences were not statistically significant (P = 0.648 and 0.619, respectively).

Conclusions

This study found no gender difference in the VMO:VL EMG intensity ratio in asymptomatic participants. This suggests that the difference in incidence of patellofemoral pain syndrome between genders is not influenced by quadriceps intensity ratios, when participants are asymptomatic.     

Effects of walking with a “draw-in maneuver” on the knee adduction moment and hip muscle activity

[Purpose] To investigate the effect of performing a draw-in maneuver (DI) on knee adduction moment (KAM) and hip and trunk muscle activities while walking. [Participants and Methods] We included 30 healthy young adults (21.5 ± 0.6 years, 16 males and 14 females) in this study. We measured the KAM and lever arm while participants walked with either a normal gait or a DI gait. We also performed surface electromyography (EMG) of the hip and trunk muscles (i.e., internal oblique abdominal muscle [IO], external oblique abdominal muscle [EO], multifidus muscle [MF], and gluteus medius muscle [GM]). [Results] The 1st peak of the KAM was significantly lower when walking with a DI gait compared to when walking with a normal gait. The integrated EMG activity of the IO, EO, and GM during the 1st half of the stance phase, and of the IO and EO during the 2nd half of the stance phase was significantly higher during the DI than during normal gait. [Conclusion] Compared with a normal gait, a DI gait leads to a decrease in the 1st peak of the KAM as a result of the shorter lever arm, and an increase in the muscular activity of the GM, IO, and EO.Key words: Draw-in maneuver, Knee adduction moment, Hip abduction muscle activity     

股内侧斜肌在髌股关节不稳中作用的影像学研究进展

髌股关节不稳在年轻人群中常见,诸多因素可致髌股关节不稳,其中动力因素中股内侧肌与股外侧肌协调性不一致是重要原因之一。髌股关节不稳会对肌肉生物力学及功能状态造成影响,进一步导致临床常见的髌股关节疼痛。利用影像学技术评估股内侧斜肌在髌股关节不稳中的功能变化及早期指导临床治疗是现阶段研究的热点。本文对股内侧斜肌在髌股关节不稳患者中的作用及相关影像学研究进展进行综述。     

A novel method for measuring electromechanical delay of the vastus medialis obliquus and vastus lateralis

Electromechanical delay (EMD) of the vastus medialis obliquus (VMO) and vastus lateralis (VL) is determined by measuring the interval between the time of onset of muscle activities and the time of onset of mechanical output. However, individual mechanical output of the VMO or the VL cannot be obtained with the conventional method because of the knee extension force as the mechanical output. Therefore, the objective of the present study was to develop a new method for measuring EMD of the VMO and VL individually. Twelve healthy volunteers participated in the experiment. The motor point of the target muscle was electrically stimulated to evoke a muscle twitch. Simultaneously, the electrical stimulation signal was transmitted to ultrasound apparatus via the electrocardiography input channel. The ultrasound apparatus was used to capture the patellar movement elicited by the muscle twitch. EMD was measured from the onset of the electrical stimulation to the onset of patellar movement. The results showed that the intraclass correlation coefficients for the reproducibility of the EMD measurements of the VMO and VL were greater than 0.8. The EMDs of the VMO and VL were 18.3 +/- 2.2 ms and 24.8 +/- 5.8 ms, respectively. This new method provides a more precise measurement of EMD in the VMO and VL than does the conventional method because of the use of patellar movement as the mechanical output.