Search Results (18)

Objectives: The present study aimed to investigate changes in forearm muscle activity associated with short-term go-kart driving (680 m) and its potential effect on muscle activation patterns. Methods: Eleven male karting league drivers (mean age: 23.18 ± 1.40 years; body mass: 83.27 ± 10.98 kg; height: 182.73 ± 5.66 cm) volunteered to participate. Electromyographic (EMG) activity was recorded from four muscles: extensor carpi radialis (ECR), extensor carpi ulnaris (ECU), flexor carpi radialis (FCR), and flexor carpi ulnaris (FCU). Baseline EMG was measured before the intervention, followed by two consecutive kart-driving sessions on a 680 m closed track. Post-exercise EMG data were then collected. A repeated-measures analysis of covariance (ANCOVA) was used to analyze the effects of time (pre vs. post) while controlling for cumulative race time as a covariate. Results: A significant time effect with cumulative time as a covariate was observed, particularly in the ECR and ECU muscles on both the left and right sides. Notable findings include increases in maximum and mean activity of the left and right ECR (e.g., ECR right max: F = 51.57; p < 0.001; η² = 0.851) and ECU (e.g., ECU right max: F = 36.170; p < 0.001; η² = 0.801). Additionally, a significant increase was found in the maximum activation of the left FCR (F = 11.019; p = 0.009; η² = 0.550, which remained significant after controlling for total driving time. This heightened activation likely reflects an acute neuromuscular fatigue response to the demands of kart steering, rather than a long-term adaptation. Conclusions: The findings suggest that even short bouts of kart driving can induce measurable changes in neuromuscular activation of the forearm muscles, particularly in those involved in grip control and steering stability. This highlights the physical demands of karting and its potential impact on the upper limb muscle conditioning. Full article

The study of muscle activation patterns using surface electromyography (sEMG) provides critical insights into muscle coordination, enabling advancements in prosthetics, robotics, and rehabilitation by improving intuitive control, replicating human movements, and developing targeted therapeutic strategies. The study involved 15 healthy participants aged 20–27, using Trigno Avanti sensors to record sEMG signals from forearm muscles during specific gestures, with data processed into activation maps to analyze muscle activity and coordination for applications in rehabilitation and prosthetics. The results revealed distinct muscle activation patterns for each gesture, highlighting precise muscle coordination, with specific muscles like m. flexor carpi ulnaris and m. extensor digitorum showing varying levels of involvement depending on the movement, while m. brachioradialis remained inactive across all gestures. The study’s findings enhance our understanding of motor control by revealing specific muscle activation patterns for different hand gestures, highlighting the selectivity of muscle coordination, and suggesting avenues for future research to improve prosthetic design and rehabilitation strategies. Full article

In ulnar neuropathy at the elbow (UNE), the degree of neuropathic changes, the sensitivity of needle electromyography (EMG) in individual ulnar muscles, and the utility of individual EMG parameters are controversial. I compared qualitative needle EMG findings in two ulnar-innervated hands muscles and two ulnar-innervated forearm muscles in a group of previously reported UNE patients. Altogether, 170 UNE patients (175 arms) were studied. I found spontaneous denervation activity (SDA) most frequently in the first dorsal interosseus (FDI) (62%) and neuropathic changes in the abductor digiti minimi (ADM) muscle (88%). In the forearm muscles, SDA was more common (29% vs. 20%; p = 0.02), and neuropathic changes were similar in the flexor carpi ulnaris (FCU) and the flexor digitorum profundus (FDP) muscles. SDA and neuropathic changes were more common in the ulnar hand (88% and 77%) than in the ulnar forearm muscles (71% and 68%). Needle EMG is sensitive to diagnose UNE. For the detection of SDA FDI and neuropathic changes, ADM is the best muscle. Ulnar forearm muscles are less useful than ulnar hand muscles for UNE diagnosis. Full article

In forehand strokes with different grips in tennis, the forearm muscle activities, the distribution and attenuation of the impact loads, and the effects of the muscles on the impact load attenuation exhibited different characteristics. This study aimed to explore these characteristics by analyzing electromyography (EMG) and acceleration data, and comparing the differences between the Eastern and Western grips. Fourteen level II or above tennis players (ten males, aged 22.4 ± 3.6 years; four females, aged 19.8 ± 2.0 years) were recruited and instructed to perform forehand strokes using the Eastern and Western grips, respectively. The EMG of eight forearm muscles and the acceleration data at the ulnar and radial sides of the wrist and elbow were collected. The root mean square (RMS), the peaks of the impact load, the amplitude of impact load attenuation (AC), and the jerk value (Jerk) were calculated. The cross-correlation coefficients and time delays of EMG–EMG, EMG–AC, and EMG–jerk were obtained using the cross-correlation method. The results showed that in the Eastern grip group (group E), the RMS of the flexor carpi ulnaris (FCU) was significantly greater than that in the Western grip group (group W). In group E, the peaks of impact load, AC, and Jerk on the Y axis of the wrist ulnar side were all significantly higher than those in group W. The activity of the extensor digitorum commonis (EDC) had significantly different effects on the amplitude and rate of impact load attenuation at specific locations in different grips, especially at the elbow (p < 0.05). The conclusion indicated that the FCU exhibited higher levels of EMG activity in the Eastern grip. This grip responded to greater impact loads with more substantial and rapid attenuation on the wrist ulnar side. Furthermore, the EDC appeared to contribute more to the amplitude of impact load attenuation in the Western grip and to have a more significant influence on the rate of impact load attenuation in the Eastern grip, especially at the elbow. These results suggest that tennis players and coaches should pay more attention to improving the strength of the EDC and FCU, which can improve sports performance and comfort, as well as prevent sports injuries. Full article

Accurate diagnosis and classification of epileptic seizures can greatly support patient treatments. As many epileptic seizures are convulsive and have a motor component, the analysis of muscle activity can provide valuable information for seizure classification. Therefore, this paper present a feasibility study conducted on healthy volunteers, focusing on tracking epileptic seizures movements using surface electromyography signals (sEMG) measured on human limb muscles. For the experimental studies, first, compact wireless sensor nodes were developed for real-time measurement of sEMG on the gastrocnemius, flexor carpi ulnaris, biceps brachii, and quadriceps muscles on the right side and the left side. For the classification of the seizure, a machine learning model has been elaborated. The 16 common sEMG time-domain features were first extracted and examined with respect to discrimination and redundancy. This allowed the features to be classified into irrelevant features, important features, and redundant features. Redundant features were examined with the Big-O notation method and with the average execution time method to select the feature that leads to lower complexity and reduced processing time. The finally selected six features were explored using different machine learning classifiers to compare the resulting classification accuracy. The results show that the artificial neural network (ANN) model with the six features: IEMG, WAMP, MYOP, SE, SKEW, and WL, had the highest classification accuracy (99.95%). A further study confirms that all the chosen eight sensors are necessary to reach this high classification accuracy. Full article

Background: Ulnar nerve entrapment is one of the most common entrapment neuropathies, usually occurring in the cubital tunnel of the elbow and in Guyon’s canal of the wrist. However, it can also occur at other anatomical locations. Purpose: Our aim was to review other possible locations of ulnar nerve entrapment in an ultrasound and anatomical study. Material and Methods: Eleven upper limbs from eight adult corpses were ultrasonographically examined and subsequently dissected in a dissection laboratory. Four specific anatomical points were analysed, and any anatomical variations were documented. Moreover, six samples of the nerve were taken for histological analysis. Results: Distinct anatomical relationships were observed during ultrasound and dissection between the ulnar nerve and the medial intermuscular septum, the triceps aponeurosis, Osborne’s fascia at the elbow, the arcuate ligament of Osborne and the intermuscular aponeurosis between the flexor carpi ulnaris and the flexor digitorum superficialis muscles. A statistical study showed that these locations are potential areas for ulnar nerve compression. In addition, a fourth head of the triceps brachii muscle was found in some specimens. Conclusion: Results demonstrate that ultrasound is a good tool to investigate ulnar nerve entrapment neuropathy and to identify other anatomical points where the nerve can remain compressed. Full article

The harder the forearm flexor–pronator muscles (FPMs) relative to the ulnar collateral ligament (UCL), the less likely it is for UCL laxity to occur with repeated pitching. This study aimed to clarify what selective contraction of the forearm muscles makes FPMs harder relative to UCL. The study evaluated 20 elbows of male college students. Participants selectively contracted the forearm muscles in eight conditions under gravity stress. The medial elbow joint width and the strain ratio indicating tissue hardness of the UCL and FPMs during contraction were evaluated using an ultrasound system. Contraction of all FPMs (in particular flexor digitorum superficialis [FDS] and pronator teres [PT]) decreased the medial elbow joint width compared to rest (p < 0.05). UCL hardens due to the contraction involving the FDS muscle (p < 0.05). FPMs harden due to the contraction of flexor carpi ulnaris (FCU) and FDS (p < 0.05). In the ratio of strain ratio UCL/FPMs, there was no significant difference between rest and each contraction task (p > 0.05). However, contractions composed of FCU and PT tended to harden FPMs relative to the UCL. FCU and PT activation may be effective in UCL injury prevention. Full article

We aimed to determine the effect of vibration frequency and direction on upper-limb muscle activation using a handheld vibrator. We recruited 19 healthy participants who were instructed to hold a handheld vibrator in their dominant hand and maintain the elbow at 90° flexion, while vertical and horizontal vibrations were applied with frequencies of 15, 30, 45, and 60 Hz for 60 s each. Surface electromyography (EMG) measured the activities of the flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), extensor carpi radialis (ECR), biceps, triceps, and deltoid anterior muscles. EMG changes were evaluated as the difference in muscle activity between vibration and no-vibration (0 Hz) conditions. Muscle activity was induced under vibration conditions in both vertical and horizontal (p < 0.05) directions. At 45 Hz, FDS and FCR activities increased during horizontal vibrations, compared with those during vertical vibrations. ECU activity significantly increased under 15-Hz vertical vibrations compared with that during horizontal vibrations. Vibrations from the handheld vibrator significantly induced upper-limb muscle activity. The maximum muscle activations for FDS, ECR, ECU, biceps, and triceps were induced by 45-Hz horizontal vibration. The 60-Hz vertical and 30-Hz horizontal vibrations facilitated maximum muscle activations for the FCR and deltoid anterior, respectively. Full article

We aimed to clarify changes cross-sectional area (CSA) in flexor pronator muscles and the ulnar nerve (UN) in players with medial elbow pain between pitching phases. Forty-two male baseball players with and without medial elbow pain during throwing were included in this study. The players were divided into maximum external rotation (MER) and ball release (BR) groups according to the pitching phase in which pain was reported. The imaged region was the flexor digital profundus, flexor carpi ulnaris (FCU), flexor digitorum superficialis, and pronator teres muscles, as well as the UN. CSA at rest and during contraction was assessed using the ultrasonography software tracing function. For statistical analysis, the CSA at rest and at contraction in the healthy group, MER group and BR group was compared using one-way analysis of variance. There was a significant difference in CSA only in the FCU between the healthy (95.4 ± 15.5%) and the MER group (76.6 ± 12.5%) at rest (p = 0.004). There were significant differences in the UN between the healthy (105.0 ± 27.7%) and MER groups (176.4 ± 53.5%), and between the healthy and BR groups (132.9±21.1%) (p = 0.001 and p = 0.038, respectively). Our results suggest that athletes with medial elbow pain during the MER of pitching have ulnar nerve swelling. Full article

Typical harvesting baskets (TB) are used in various agricultural workplaces; however, no study to date has reported their effect on the musculoskeletal system. Therefore, this study aimed to evaluate the effects of a novel basket with attached rotational handles (RHB) to help alleviate the work-related physical burden of farmers. We analyzed the surface electromyograms (EMGs) of seven muscles, evaluated the subjective discomfort levels and locally perceived discomfort (LPD) scores to investigate the discomfort in the whole body and seven hand muscles, respectively. The EMGs showed that muscle activity decreased in five muscles (flexor carpi ulnaris, extensor carpi radialis, lateral triceps, middle deltoid, and upper trapezius) and increased in two (biceps brachii and erector spinae) when the RHB was used (p < 0.05). The subjective discomfort score for the RHB decreased compared to that for TB (p < 0.001). The LPD scores also decreased, and the RHB and TB scores ranged from 1.25–1.40 and 3.1–3.25, respectively. The use of the RHB may prevent wrist bending, and reduce the activity of certain muscles while increasing the activity of other muscles. Therefore, it is necessary to conduct training and to evaluate the working posture while considering the affected muscles. Full article

Recent literature has demonstrated that high-resolution ultrasonographic anatomy of the canine carpus is possible; however, only the structures of the dorsal face were described. The aims of this prospective study were: (1) to describe the normal ultrasonographic appearance of the carpal tendons in sporting Border Collies; (2) to measure the height, length, and thickness of the tendon at the radial ulnar notch level in order to create a baseline reference for the breed, and (3) to describe a standardised protocol to ultrasonographically evaluate the carpal faces and visible tendinous structures. A pilot study based on ten cadaveric front limbs was used to identify the structures. A subsequent clinical phase of the study using twenty-six Border Collies was recorded. The tendons of the Extensor Carpi Radialis, Extensor Digitorum Communis, and Extensor Digitorum Lateralis were identified and followed from the tenomuscular junction to the distal insertion on the dorsal face of the digits. On the lateral face, the tendon of the Extensor Carpi Ulnaris was recognised and followed. On the palmar face, the two heads of the Flexor Carpi Ulnaris tendon ending on the accessory carpal bone, the adjacent Flexor Digitorum Superficialis tendon, and the deep and medially located Flexor Digitorum Profundus tendon were seen and followed. The Flexor Carpi Radialis and the Abductor Pollicis Longus tendons were seen in the medial carpal face. The ulnar notch of the radius was used as the measurement and starting point of the ultrasonography. These data could be used as a standard reference in the case of chronic overuse and trauma-induced changes in the canine carpus. Full article

The palmar region of the canine carpus is anatomically complex, and the information found in the literature about its anatomy is inconsistent. The aims of this prospective, descriptive, anatomic study were (1) the clarification and (2) the description of the precise anatomic composition of the palmar region of the canine carpus, with special reference to the canalis carpi. For this study, 92 cadaveric specimens were obtained from 46 dogs that had died for reasons unrelated to this study. Of these, 43 medium-to-large-breed dogs were randomly selected for the dissection of transverse slices of the carpus. Samples of the flexor retinaculum and flexor carpi radialis tendon and surrounding tissues were taken for complementary histology. For additional histology of the palmar structures in their anatomical position, three small breed dogs were randomly selected for obtaining transverse slices. The anatomic characteristics of the components of the palmar region of the canine carpus were qualitatively described, with special attention to the following structures: flexor retinaculum, flexor carpi radialis muscle, arteria and vena mediana, nervus medianus, interflexorius muscle, flexor digitorum profundus muscle, canalis carpi, and arteria and nervus ulnaris. The findings from this study provide reference information about the anatomy of the palmar region of the canine carpus. Full article

To systematically review the effects of exercise on fascicle geometry and muscle size parameters of the upper extremity muscles, the CENTRAL, CINAHL, PubMed and OpenGrey databases were searched on 31 July 2021. Finally, 17 randomised controlled trials (RCTs) were included in this systematic review. High-intensity bench press training (g = 1.03) and 12 RM bench press exercises (g = 1.21) showed a large effect size on increasing pectoralis major muscle size. In the elbow extensors, large effects were reported for an increase in muscle size with isometric maximal voluntary co-contraction training (g = 1.97), lying triceps extension exercise (g = 1.25), and nonlinear periodised resistance training (g = 2.07). In addition, further large effects were achieved in the elbow flexors via traditional elbow flexion exercises (g = 0.93), concentric low-load forearm flexion-extension training (g = 0.94, g = 1), isometric maximal voluntary co-contraction training (g = 1.01), concentric low-load forearm flexion-extension training with blood flow restriction (g = 1.02, g = 1.07), and nonlinear periodised resistance training (g = 1.13, g = 1.34). Regarding the forearm muscles, isometric ulnar deviation training showed a large effect (g = 2.22) on increasing the flexor carpi ulnaris and radialis muscle size. Results show that these training modalities are suitable for gaining hypertrophy in the relevant muscles with at least four weeks of training duration. Future RCTs should investigate the effects of exercise modalities on the triceps brachii fascicle geometry, the infraspinatus muscle thickness (MT) and the subscapular MT due to their associations with sports performance. Full article

The surface Electromyography (sEMG) signal contains information about movement intention generated by the human brain, and it is the most intuitive and common solution to control robots, orthotics, prosthetics and rehabilitation equipment. In recent years, gesture decoding based on sEMG signals has received a lot of research attention. In this paper, the effects of muscle fatigue, forearm angle and acquisition time on the accuracy of gesture decoding were researched. Taking 11 static gestures as samples, four specific muscles (i.e., superficial flexor digitorum (SFD), flexor carpi ulnaris (FCU), extensor carpi radialis longus (ECRL) and finger extensor (FE)) were selected to sample sEMG signals. Root Mean Square (RMS), Waveform Length (WL), Zero Crossing (ZC) and Slope Sign Change (SSC) were chosen as signal eigenvalues; Linear Discriminant Analysis (LDA) and Probabilistic Neural Network (PNN) were used to construct classification models, and finally, the decoding accuracies of the classification models were obtained under different influencing elements. The experimental results showed that the decoding accuracy of the classification model decreased by an average of 7%, 10%, and 13% considering muscle fatigue, forearm angle and acquisition time, respectively. Furthermore, the acquisition time had the biggest impact on decoding accuracy, with a maximum reduction of nearly 20%. Full article

In this research paper, we implemented a mixed factor design in order to investigate the effect of four anthropometries: height, weight, lower-arm dimensions, and upper-arm dimensions on the muscle activation level of participants when interacting with three types of moderators: experiment expertise, task type, and muscle type. The research paper focused on two levels of expertise (novice and expert), two tasks (deck-building and picket installation), and four arm muscles (Brachioradialis (BR), Extensor Carpi Ulnaris (ECU), Flexor Carpi Radialis (FCR), and Flexor Carpi Ulnaris (FCU)), which resulted in 16 (2 × 2 × 4) groups. For each of the 16 groups, the data were analyzed in order to investigate the relationship between the four anthropometries and the four muscle activation levels of the participants. Amos software (IBM, Armonk, NY, USA), along with multiple group structural equation modeling, was used to test a total of 16 direct relationships, as well as the moderation effects in the designed experiment. The results show that the participants’ expertise can moderate the relationship between their height and muscle activation levels, the relationship between their weight and muscle activation levels, and the relationship between their lower arm dimensions and muscle activation levels. Moreover, the findings of this research paper demonstrate that the relationship between the lower arm dimensions and muscle activation levels, and the relationship between weight and muscle activation levels are moderated by the type of muscle used by the participants (i.e., BR, ECU, FCR, and FCU). Full article