An electromyographical study to investigate the effects of patellar taping on the vastus medialis/vastus lateralis ratio in asymptomatic participants

Inhibition of knee joint sensory afferents alters covariation across strides between quadriceps muscles during locomotion

Sport-related injuries to articular structures often alter the sensory information conveyed by joint structures to the nervous system. However, the role of joint sensory afferents in motor control is still unclear. Here, we evaluate the role of knee joint sensory afferents in the control of quadriceps muscles, hypothesizing that such sensory information modulates control strategies that limit patellofemoreal joint loading. We compared locomotor kinematics and muscle activity before and after inhibition of knee sensory afferents by injection of lidocaine into the knee capsule of rats. We evaluated whether this inhibition reduced the strength of correlation between the activity of vastus medialis (VM) and vastus lateralis (VL) both across strides and within each stride, coordination patterns that limit net mediolateral patellofemoral forces. We also evaluated whether this inhibition altered correlations among the other quadriceps muscle activity, the time-profiles of individual EMG envelopes, or movement kinematics. Neither the EMG envelopes nor limb kinematics was affected by the inhibition of knee sensory afferents. This perturbation also did not affect the correlations between VM and VL, suggesting that the regulation of patellofemoral joint loading is mediated by different mechanisms. However, inhibition of knee sensory afferents caused a significant reduction in the correlation between vastus intermedius (VI) and both VM and VL across, but not within, strides. Knee joint sensory afferents may therefore modulate the coordination between the vasti muscles but only at coarse time scales. Injuries compromising joint afferents might result in altered muscle coordination, potentially leading to persistent internal joint stresses and strains.NEW & NOTEWORTHY Sensory afferents originating from knee joint receptors provide the nervous system with information about the internal state of the joint. In this study, we show that these sensory signals are used to modulate the covariations among the activity of a subset of vasti muscles across strides of locomotion. Sport-related injuries that damage joint receptors may therefore compromise these mechanisms of muscle coordination, potentially leading to persistent internal joint stresses and strains.

Coordination amongst quadriceps muscles suggests neural regulation of internal joint stresses, not simplification of task performance

Many studies have demonstrated covariation between muscle activations during behavior, suggesting that muscles are not controlled independently. According to one common proposal, this covariation reflects simplification of task performance by the nervous system so that muscles with similar contributions to task variables are controlled together. Alternatively, this covariation might reflect regulation of low-level aspects of movements that are common across tasks, such as stresses within joints. We examined these issues by analyzing covariation patterns in quadriceps muscle activity during locomotion in rats. The three monoarticular quadriceps muscles (vastus medialis [VM], vastus lateralis [VL], and vastus intermedius [VI]) produce knee extension and so have identical contributions to task performance; the biarticular rectus femoris (RF) produces an additional hip flexion. Consistent with the proposal that muscle covariation is related to similarity of muscle actions on task variables, we found that the covariation between VM and VL was stronger than their covariations with RF. However, covariation between VM and VL was also stronger than their covariations with VI. Since all vastii have identical actions on task variables, this finding suggests that covariation between muscle activity is not solely driven by simplification of overt task performance. Instead, the preferentially strong covariation between VM and VL is consistent with the control of internal joint stresses: Since VM and VL produce opposing mediolateral forces on the patella, the high positive correlation between their activation minimizes the net mediolateral patellar force. These results provide important insights into the interpretation of muscle covariations and their role in movement control.

Adaptation of muscle activation after patellar loading demonstrates neural control of joint variables

We evaluated whether the central nervous system (CNS) chooses muscle activations not only to achieve behavioral goals but also to minimize stresses and strains within joints. We analyzed the coordination between quadriceps muscles during locomotion in rats before and after imposing a lateral force on the patella. Vastus lateralis (VL) and vastus medialis (VM) in the rat produce identical knee torques but opposing mediolateral patellar forces. If the CNS regulates internal joint stresses, we predicted that after imposing a lateral patellar load by attaching a spring between the patella and lateral femur, the CNS would reduce the ratio between VL and VM activation to minimize net mediolateral patellar forces. Our results confirmed this prediction, showing that VL activation was reduced after attaching the spring whereas VM and rectus femoris (RF) activations were not significantly changed. This adaptation was reversed after the spring was detached. These changes were not observed immediately after attaching the spring but only developed after 3–5 days, suggesting that they reflected gradual processes rather than immediate compensatory reflexes. Overall, these results support the hypothesis that the CNS chooses muscle activations to regulate internal joint variables.

The Effect of Kinesiology Taping on the Hemiplegic Shoulder Pain: A Randomized Controlled Trial

Objective

The purpose of the study was to explore the effect of kinesiology taping on hemiplegic shoulder pain (HSP) in terms of pain intensity, magnitude of subluxation, muscle activity, and active range of motion (AROM).

Design

Double-blind, placebo-controlled clinical trial.

Setting

the Rehabilitation Center of the West China Hospital.

Participants

Nineteen individuals suffering from HSP were recruited in this study.

Intervention

Patients were randomly assigned into the taping group or control group. The taping group received therapeutic kinesiology taping and conventional treatment, while the control group received placebo taping (applied without tension) and conventional treatment.

Main Outcome Measures

The shoulder pain intensity (numerical pain rating scale), magnitude of subluxation, muscle activity (measured by surface electromyography (sEMG)), and shoulder active range of movement (AROM) were assessed at the baseline, on the first day (immediately after taping) and 4 weeks after treatment (without taping).

Results

All patients completed the trials. There were no significant differences between groups at the baseline. The taping group showed immediate improvement on the first day after taping in terms of pain intensity, magnitude of subluxation, and muscle activity (p < 0.05), whereas no significant changes seen in the control group (p > 0.05). After 4 weeks of treatment, the taping group showed significant changes in pain intensity, magnitude of subluxation, muscle activity, and AROM (p < 0.05). And significant differences in pain intensity and muscle activity could be seen between the two groups (p < 0.05).

Conclusion

The results indicate that the kinesiology taping is effective in reducing the shoulder pain and subluxation and increasing muscle activity and AROM for patients with HSP after stroke.

Gait analysis of elderly women after total knee arthroplasty

[Purpose] The purpose of this study was to investigate ability and muscle activities of elderly women after total knee arthroplasty (TKA) and compare them with those of healthy ones. [Subjects and Methods] Fifteen female patients with TKA due to advanced degenerative arthritis of the measured on knee joint and 19 healthy elderly females participated. Tibiofemoral angles of TKA patients were using a gait analysis system anterioposterior X-rays of the weight-bearing knee. The knee flexion angle and gait parameters were measured. Muscle activities and prolongation time were EMG system. The gait of the treated limb of each participant was evaluated in three consecutive trials at fast speed and comfortable speed. [Results] The knee flexion angle %stance phase, stride length, step length, speed, cadence, and gait cycle significantly decreased at both the fast speed and comfortable speeds, and the onset and duration time of rectus femoris activity was significantly increased at the comfortable speed in the TKA group. [Conclusion] In conclusion, elderly women who received TKA showed decreased gait ability and muscle activity compared to the healthy elderly women.

Immediate effect and predictors of effectiveness of taping for patellofemoral pain syndrome: a prospective cohort study

BACKGROUND

Taping has been used to treat patellofemoral pain syndrome for more than 20 years, but its effectiveness is still controversial.

PURPOSE

This study was undertaken to investigate the effect and predictors of effectiveness of taping in the treatment of patellofemoral pain syndrome.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 118 consecutive patients with patellofemoral pain syndrome were recruited; 100 of them completed this study. Patient sex, age, body mass index, Q angle, lateral patellar displacement, and lateral patellofemoral angle were recorded/measured. One therapist applied adhesive tape to each patient by the McConnell method. Patients scored their pain level on a 100-mm visual analog scale during stepping down from an 8-in platform, before and after taping. The change of score was evaluated by paired t test. Patients with a visual analog scale score decrease of 20 mm or more after taping were considered responsive, and the others were considered nonresponsive. The influences of the aforementioned factors, plus pretaping visual analog scale score, on the effectiveness of taping were analyzed by multivariate logistic regression.

RESULTS

The overall mean visual analog scale score decreased significantly after taping (from 49.0 to 29.3 mm; P < .001). There were 66 patients in the responsive group and 34 in nonresponsive group. Among the factors, body mass index, lateral patellofemoral angle, and Q angle were significant predictors of effectiveness. The responsive group had significantly smaller mean lateral patellofemoral angle, larger mean Q angle, and larger mean pretaping visual analog scale score than the nonresponsive group.

CONCLUSION

Taping was an effective treatment for patellofemoral pain syndrome, but was less effective in patients with higher body mass index, larger lateral patellofemoral angle, and smaller Q angle.

Effect of shoe heel height on vastus medialis and vastus lateralis electromyographic activity during sit to stand

Background

It has been proposed that high-heeled shoes may contribute to the development and progression of knee pain. However, surprisingly little research has been carried out on how shoe heel height affects muscle activity around the knee joint. The purpose of this study was to investigate the effect of differing heel height on the electromyographic (EMG) activity in vastus medialis (VM) and vastus lateralis (VL) during a sit to stand activity. This was an exploratory study to inform future research.

Methods

A repeated measures design was used. Twenty five healthy females carried out a standardised sit to stand activity under 4 conditions; barefoot, and with heel wedges of 1, 3, and 5 cm in height. EMG activity was recorded from VM and VL during the activity. Data were analysed using 1 × 4 repeated measures ANOVA.

Results

Average rectified EMG activity differed with heel height in both VM (F_{2.2, 51.7} = 5.24, p < 0.01), and VL (F_{3, 72} = 5.32, p < 0.01). However the VM: VL EMG ratio was not significantly different between conditions (F_{3, 72} = 0.61, p = 0.609).

Conclusion

We found that as heel height increased, there was an increase in EMG activity in both VM and VL, but no change in the relative EMG intensity of VM and VL as measured by the VM: VL ratio. This showed that no VM: VL imbalance was elicited. This study provides information that will inform future research on how heel height affects muscle activity around the knee joint.