Effects of feedback on activation of the quadriceps during weight-bearing tasks of the Wii

[Purpose] This investigation evaluated the effect of real-time feedback on electrical activation of the quadriceps during 3 weight-bearing tasks of the Wii Fit Plus^®. [Subjects] Thirty male healthy volunteers were recruited. [Methods] Activation of the vastus medialis, vastus lateralis, and rectus femoris muscles was recorded during virtual lunge, single leg extension, and single leg reach exercises. Each exercise was performed twice in 3 randomized experimental conditions (with visual feedback, with auditory feedback, and with no feedback). The normalized electromyographic data (using maximum voluntary isometric contraction) were analyzed using repeated measures analysis of variance and Tukey’s test. [Results] No significant difference was found in the muscles among the feedback conditions during the 3 exercises. However, the variation in the muscle activity of the vastus medialis and vastus lateralis (18.23–29.20% of maximum voluntary isometric contraction) was higher (47–62%) than that in the rectus femoris (7.35–12.98% of maximum voluntary isometric contraction). [Conclusion] Real-time feedback did not alter quadriceps activation during the Wii tasks. Additionally, these games showed electromyographic activation levels similar to those for the same tasks outside the virtual environment. The Wii weight-bearing tasks could therefore constitute a physical activity program but without the additional benefit of feedback.Key words: Electromyography, Functional exercises, Exergames     

A Study on the Differences of Quadriceps Femoris Activities by Knee Alignment during Isometric Contraction

[Purpose] This study attempted to identify how genu varum or valgum affects the electromyographic activities of the vastus medialis, vastus lateralis, and rectus femoris during knee isometric contraction. [Subjects] Fifty-two healthy young adults were enrolled in this study. They were enrolled and classified into three groups by knee alignment conditions: the genu varum, genu valgum, and control groups. [Methods] The electromyographic activity ratio of the vastus medialis to the vastus lateralis and rectus femoris were calculated using the percentage of maximum voluntary contraction. The participants contracted their quadriceps during isometric contraction at 30 and 60° of knee flexion. [Results] The genu varum group had more activity in the vastus medialis than in the vastus lateralis and rectus femoris, whereas the genu valgum group had more activity in the vastus lateralis and rectus femoris than in the vastus medialis. There was a significant difference in the muscle activity ratio between the vastus medialis and vastus lateralis by angle of knee flexion degree only in the genu valgum. There were no significant differences in any of the three groups in terms of the muscle activity ratio of the vastus medialis to the rectus femoris by angle of knee flexion. [Conclusion] The quadriceps femoris was used for different strategies according to knee alignment during isometric contraction at 30 and 60°. This study suggests that rehabilitation training programs used to strengthen the quadriceps should consider the knee alignment conditions of the target subjects.Key words: Electromyography, Quadriceps muscle, Isometric contraction     

Relationship between knee alignment and the electromyographic activity of quadriceps muscles in patients with knee osteoarthritis

[Purpose] We evaluated the relationship between knee alignment and the electromyographic (EMG) activity of the vastus medialis (VM) to the vastus lateralis (VL) muscles in patients with knee osteoarthritis (OA) in a cross-sectional study. [Subjects and Methods] Forty subjects with knee OA were assessed by anatomic radiographic knee alignment and the VM/VL ratio was calculated. Surface EMG from both the VM and VL muscles were evaluated during maximal isometric contraction at 60° knee flexion. Simultaneously, peak quadriceps torque was assessed using an isokinetic dynamometer. Subjects were categorized into low, moderate, and high varus groups according to knee malalignment. The peak quadriceps torque and VM/VL ratio across groups, and their relationships with varus malalignment were analyzed. [Results] All subjects had medial compartment OA and the VM/VL ratio of all subjects was 1.31 ± 0.28 (mean ± SD). There were no significant differences in the peak quadriceps torque or VM/VL ratios across the groups nor were there any significant relationships with varus malalignment. [Conclusion] The VM/VL ratio and peak quadriceps torque were not associated with the severity of knee varus malalignment.Key words: Malalignment, Knee, Quadriceps     

Combined indocyanine green and quantitative perfusion assessment with hyperspectral imaging during colorectal resections

Anastomotic insufficiencies still represent one of the most severe complications in colorectal surgery. Since tissue perfusion highly affects anastomotic healing, its objective assessment is an unmet clinical need. Indocyanine green-based fluorescence angiography (ICG-FA) and hyperspectral imaging (HSI) have received great interest in recent years but surgeons have to decide between both techniques. For the first time, two data processing pipelines capable of reconstructing an ICG-FA correlating signal from hyperspectral data were developed. Results were technically evaluated and compared to ground truth data obtained during colorectal resections. In 87% of 46 data sets, the reconstructed images resembled the ground truth data. The combined applicability of ICG-FA and HSI within one imaging system might provide supportive and complementary information about tissue vascularization, shorten surgery time, and reduce perioperative mortality.     

Electromyographic activity of the quadriceps components during the final degrees of knee extension

An imbalance in the recruitment patterns of the quadriceps muscle has been implicated in patellofemoral knee pain; however ambiguity remains in the normal recruitment patterns of this muscle. We investigated the activity of the quadriceps muscle during the final degrees of knee extension, specifically in the medial and lateral components. Sixteen healthy subjects (age; 22.5 (± 3.4) years, body mass; 67.5 (± 12.1) kg and height; 173.9 (± 10.4) cm) participated.Torque and electromyographic (EMG) activity of the quadriceps muscle were measured during isokinetic and isometric knee extensions. Torque and EMG activity reduced in all component muscles during the final degrees of isokinetic extension, but this did not occur during isometric contractions at similar angles. Normalised activity of rectus femoris (RF) was greater than that of vastus lateralis (VL) and vastus medialis obliquus (VMO) during the final degrees of isokinetic knee extension at 30°/sec; there were no differences between any component muscles at the higher velocities. VMO:VL and vastus medialis longus (VML):VL ratios were unchanged during knee extensions, except that VML:VL ratio increased significantly during the final degrees of extension at 30°/sec. Future work should compare these results with people with anterior knee pain, and explore this further during activities of daily living.     

Influence of exercise intensity on atrophied quadriceps muscle in the rat

[Purpose] The aim of this study was to determine the effect of resistance training on atrophied skeletal muscle in rats based on evidence derived from physical therapy. [Subjects and Methods] Rats were forced to undergo squats as resistance training for 3 weeks after atrophying the rectus femoris muscle by hindlimb suspension for 2 weeks. The intensity of resistance training was adjusted to 50% and 70% of the maximum lifted weight, i.e., 50% of the one-repetition maximum and 70% of the one-repetition maximum, respectively. [Results] Three weeks of training did not alter the one-repetition maximum, and muscle fibers were injured while measuring the one-repetition maximum and reloading. The decrease in cross-sectional area in the rectus femoris muscle induced by unloading for 2 weeks was significantly recovered after training at 70% of the one-repetition maximum. The levels of muscle RING-finger protein-1 mRNA expression were significantly lower in muscles trained at 70% of the one-repetition maximum than in untrained muscles. [Conclusion] These results suggest that high-intensity resistance training can promote atrophic muscle recovery, which provides a scientific basis for therapeutic exercise methods for treatment of atrophic muscle in physical therapy.Key words: Muscle atrophy, Quadriceps muscle, Resistance training     

Effect of foot orthotics on quadriceps and gluteus medius electromyographic activity during selected exercises

OBJECTIVE: To compare electromyographic activity of the vastus medialis, vastus lateralis, and gluteus medius during functional activities in subjects with different foot types while wearing various off-the-shelf foot orthotics. DESIGN: Experimental, controlled; 3 foot-type groups (pes planus, pes cavus, pes rectus) each tested in 4 orthotic conditions while performing 3 different exercises. SETTING: Laboratory. PARTICIPANTS: Thirty healthy young adults, 10 with each foot type. INTERVENTIONS: Four conditions: no orthotic, 7 degrees medial rearfoot post, 4 degrees lateral rearfoot post, and neutral rearfoot post. MAIN OUTCOME MEASURE: Surface electromyographic activity for the vastus medialis, vastus lateralis, and gluteus medius during single-leg squatting, lateral stepdown, and maximum vertical jump exercises. RESULTS: Greater vastus medialis and gluteus medius activity was found with all 3 orthotic conditions, regardless of subject foot type, during the single-leg squat and lateral stepdown. Less vastus lateralis activity was found with the vertical jump with all orthotic conditions, again regardless of foot type. CONCLUSIONS: During slow controlled exercises such as the single-leg squat and lateral stepdown, vastus medialis and gluteus medius activity may be enhanced with an off-the-shelf orthotic, regardless of posting or foot type. These same findings do not appear to carry over to a more explosive task such as the maximal vertical jump.     

EMG comparison of quadriceps femoris activity during knee extension and straight leg raises.

Both knee extension and straight leg raises have been used to rehabilitate atrophied quadriceps musculature following knee immobilization. A comparison of the tension developed during these two exercises was made in each of the three surface quadriceps muscles (quadriceps femoris, vastus lateralis, vastus medialis) at three different levels of activity (20%, 50%, and 80% of 1RM). Integrated EMG (m Volt-seconds) was used to measure tension developed during a seven second contraction. Tension developed was significantly greater during a seven second contraction. Tension developed was significantly greater during knee extension than during straight leg raises at each exercise intensity. For both exercises and at all three exercise levels, the vastus lateralis was the most active; the vastus medialis was the least active. The difference between knee extension and straight leg raises became greater with increasing levels of activity. Therefore, unless contraindicated by chondromalacia of lack of knee flexibility, knee extensions should be used for post-surgical knee rehabilitation. The greater tension development would lead to a more rapid return of strength, and therefore quicker rehabilitation.     

Longitudinal assessment of grip strength using bulb dynamometer in Duchenne Muscular Dystrophy

BACKGROUND:

Grip strength is used to infer functional status in several pathological conditions, and the hand dynamometer has been used to estimate performance in other areas. However, this relationship is controversial in neuromuscular diseases and studies with the bulb dynamometer comparing healthy children and children with Duchenne Muscular Dystrophy (DMD) are limited.

OBJECTIVE:

The evolution of grip strength and the magnitude of weakness were examined in boys with DMD compared to healthy boys. The functional data of the DMD boys were correlated with grip strength.

METHOD:

Grip strength was recorded in 18 ambulant boys with DMD (Duchenne Group, DG) aged 4 to 13 years (mean 7.4±2.1) and 150 healthy volunteers (Control Group, CG) age-matched using a bulb dynamometer (North Coast- NC70154). The follow-up of the DG was 6 to 33 months (3-12 sessions), and functional performance was verified using the Vignos scale.

RESULTS:

There was no difference between grip strength obtained by the dominant and non-dominant side for both groups. Grip strength increased in the CG with chronological age while the DG remained stable or decreased. The comparison between groups showed significant difference in grip strength, with CG values higher than DG values (confidence interval of 95%). In summary, there was an increment in the differences between the groups with increasing age. Participants with 24 months or more of follow-up showed a progression of weakness as well as maintained Vignos scores.

CONCLUSIONS:

The amplitude of weakness increased with age in the DG. The bulb dynamometer detected the progression of muscular weakness. Functional performance remained virtually unchanged in spite of the increase in weakness.     

Differences in quadriceps femoris muscle torque when using a clinical electrical stimulator versus a portable electrical stimulator

BACKGROUND AND PURPOSE: There have been conflicting views and evidence reported in the literature concerning differences in muscle torque-generating capacities between clinical ("plug-in") console devices whose power source is provided by an electrical outlet (60 Hz, alternating current-driven) and portable electrical muscle stimulators (smaller, battery-operated stimulators). The purpose of this study was to compare the torque-generating capacity of the quadriceps femoris muscle during neuromuscular electrical stimulation (NMES) between a clinical neuromuscular electrical stimulator (VersaStim 380) and a portable neuromuscular electrical stimulator (Empi 300PV). SUBJECTS: Forty volunteer subjects with no known knee, neurological, or cardiovascular pathology (22 male, 18 female) participated in the study. METHODS: All subjects were tested with the clinical and portable stimulators on 2 separate days. Peak isometric torque of the quadriceps femoris muscle was measured using a Biodex dynamometer. Peak isometric quadriceps femoris muscle torque achieved during NMES and the average quadriceps femoris muscle torque integral produced over 10 NMES contractions were measured for each stimulator. Subjects also rated the amount of pain they experienced during the 10 NMES contractions using a numeric pain scale. Paired t tests were used to compare mean differences in measured variables between stimulator conditions. RESULTS: There were no differences in the peak torque or numeric pain ratings during the electrically stimulated contractions between stimulator conditions. The Empi 300PV produced a greater average torque integral compared with the VersaStim 380 during 10 electrically stimulated contractions (Empi 300PV=988.6-/+330.4 N.m-s, Versastim 380=822.7-/+292.6 N.m-s). DISCUSSION AND CONCLUSION: The portable Empi 300PV stimulator produced comparable levels of average peak torque at comparable levels of discomfort to those produced by the VersaStim 380 clinical stimulator. The Empi 300PV maintained greater amounts of torque production during a 10-contraction training session compared with the VersaStim 380. Based on these data, we believe that the Empi 300PV has the potential to produce adequate levels of torque production for NMES quadriceps femoris muscle performance training. Further study is needed to determine the effectiveness of using the Empi 300PV for quadriceps femoris muscle performance training.     

Automated assessment of breast margins in deep ultraviolet fluorescence images using texture analysis

Microscopy with ultraviolet surface excitation (MUSE) is increasingly studied for intraoperative assessment of tumor margins during breast-conserving surgery to reduce the re-excision rate. Here we report a two-step classification approach using texture analysis of MUSE images to automate the margin detection. A study dataset consisting of MUSE images from 66 human breast tissues was constructed for model training and validation. Features extracted using six texture analysis methods were investigated for tissue characterization, and a support vector machine was trained for binary classification of image patches within a full image based on selected feature subsets. A weighted majority voting strategy classified a sample as tumor or normal. Using the eight most predictive features ranked by the maximum relevance minimum redundancy and Laplacian scores methods has achieved a sample classification accuracy of 92.4% and 93.0%, respectively. Local binary pattern alone has achieved an accuracy of 90.3%.     

Effects of shoe type on lower extremity muscle activity during treadmill walking

[Purpose] The purpose of this study was to analyze the effects of different shoe types on lower extremity muscle activity in healthy young women by using electromyography. [Subjects and Methods] Fifteen healthy young women in their 20s were included in this single-group repeated measures study. The subjects were divided into three groups: Converse sneakers, rain boots, and combat boots. The subjects walked on a treadmill at 4 km/h for 30 min, during which six muscles were examined using electromyography: the rectus femoris, vastus medialis, semimembranosus, tibialis anterior, peroneus longus, and medial head of the gastrocnemius. Between switching shoe types, a 24-h rest period was instated to prevent the fatigue effect from treadmill walking. [Results] One-way analysis of variance used to compare electromyography results among the three groups showed that the main effect of group differed significantly for the vastus medialis. Vastus medialis activity was higher in the rain boots group than the Converse sneakers group, and it was higher in the combat boots group than rain boots group. [Conclusion] Shoe type affects lower extremity muscle activity. Our findings may help individuals choose the ideal shoes for daily walking.Key words: Electromyography, Lower extremity, Shoe type     

Differences in Muscle Activities of the Infraspinatus and Posterior Deltoid during Shoulder External Rotation in Open Kinetic Chain and Closed Kinetic Chain Exercises

[Purpose] This study investigated the changes in electromyographic (EMG) activities of the infraspinatus and posterior deltoid muscles during shoulder external rotation under open kinetic chain (OKC) and closed kinetic chain (CKC) exercise conditions. [Subjects] In total, 15 healthy males participated in this study. [Methods] Subjects performed shoulder external rotations under CKC and OKC conditions while standing with and without weight support provided by a height-adjustable table. Pressure biofeedback was used to ensure a constant amount of weight support. The activities of the infraspinatus and posterior deltoid muscles during shoulder external rotation were measured using a wireless surface EMG system. The paired t-test was used to compare the EMG activities of the infraspinatus and the posterior deltoid muscles and the ratio of the infraspinatus to the posterior deltoid during shoulder external rotation under OKC and CKC conditions. [Results] The EMG activity of the infraspinatus and the ratio of the infraspinatus to the posterior deltoid activities were significantly increased, whereas the posterior deltoid activity was significantly decreased under the CKC condition compared to the OKC condition. [Conclusion] Clinicians should consider the CKC shoulder external rotation exercise when they wish to selectively strengthen the infraspinatus.Key words: Infraspinatus, Posterior deltoid, Selective muscle strengthening     

Relationship between muscle echo intensity on ultrasound and isokinetic strength of the three superficial quadriceps femoris muscles in healthy young adults

[Purpose] The purpose of this study was to clarify the relationship between muscle echo intensity measured with ultrasound and the isokinetic strength of each of the three superficial quadriceps femoris muscles in healthy young adults. [Participants and Methods] We measured the echo intensity of the three superficial muscles of the quadriceps femoris in 25 healthy adults (10 males and 15 females; mean age, 22.3 years) using ultrasound. Moreover, we obtained the maximum force during isokinetic knee extension at 60°/s using an isokinetic dynamometer. [Results] In males and females, a significant negative correlation between echo intensity and muscle strength was found in the VM (r=−0.65 and r=−0.63, respectively). [Conclusion] In both males and females, only the muscle echo intensity of the vastus medialis was found to have a negative correlation with the maximum force during isokinetic knee extension at 60°/s. Our data lay the foundation for simplifying and rationally performing the measurement of muscle echo intensity of the quadriceps femoris. And it would therefore be sufficient to only measure the VM to clarify a relationship between EI and maximum isokinetic force in the quadriceps.Key words: Echo intensity, Isokinetic strength, Quadriceps femoris muscle     

Comparison of the electromyographic activity of the tibialis anterior and gastrocnemius in stroke patients and healthy subjects during squat exercise

[Purpose] The purpose of this study was to compare the EMG activity of the tibialis anterior (TA) and gastrocnemius (GCM) during the downward, maintenance, and upward phases of the squat exercise and during passive ankle dorsiflexion range of motion between stroke patients and healthy subjects. [Subjects] Fifteen hemiplegic (8 males, 7 females) and 15 healthy subjects (4 males, 11 females) volunteered for this study. [Methods] All subjects performed a double-leg squat exercise with the knee joint flexed to 30°. Surface electromyography (EMG) signals were recorded from the TA and GCM on the paretic or nondominant side. Passive ankle dorsiflexion range of motion (DF PROM) was measured using a goniometer in the knee-extended prone position. [Results] In the downward and maintenance phases, TA activity was significantly higher in stroke patients compared with healthy subjects. In the upward phase, GCM activity was significantly lower in stroke patients compared with healthy subjects. Ankle DF PROM was significantly lower in stroke patients compared with healthy subjects. [Conclusion] The observed EMG patterns should be taken into consideration to inform and enhance therapy for stroke patients.Key words: EMG, Squat exercise, Stroke