Self-perceived exertion level and objective evaluation of neuromuscular fatigue in a training session of orchestral violin players

Validation of the Borg CR10 Scale for the evaluation of shoulder perceived fatigue during work-related tasks

Work-related upper extremity disorders (WRUEDs) are highly prevalent and costly. Development of fatigue is thought to be one of the causes of WRUEDs. Perceived fatigue can be assessed with the Borg CR Scale® (Borg CR10). The objective was to validate the Borg CR10 for the evaluation of shoulder perceived fatigue during lifting tasks. Seventy adults in working age performed three rhythmic lifting tasks with two loads (15% and 30% of maximal voluntary contraction). Using generalized repeated-measures ANOVA (Generalized Estimating Equations), statistically significant Task and Load effects (p < 0.001), as well as Task × Load interaction effects (p < 0.0001) were observed on Borg CR10, without any influence of sex. The Borg CR10 is a valid tool to assess shoulder perceived fatigue as it can discriminate between tasks of different difficulty levels in term of complexity, height, and resistance, regardless of sex.

Muscle fatigue during assisted violin performance

Muscle fatigue is a primary risk factor in developing musculoskeletal disorders, which affect up to 93% musicians, especially violinists. Devices providing dynamic assistive support (DAS) to the violin-holding arm can lessen fatigue. The objective was to assess DAS effects on electromyography median frequency and joint kinematics during a fatiguing violin-playing task. Fifteen university-level and professional violinists were equipped with electromyography sensors and reflective markers to record upper-body muscle activity and kinematics. They played G scales with and without DAS until exhaustion. Paired t-tests assessed DAS effects on delta (final-initial) electromyography median frequencies and joint kinematics. DAS prevented the median frequency decrease of left supraspinatus, superior trapezius, and right medial deltoid, and increases in trunk rotation, left-wrist abduction, and right arm-elevation plane. DAS effects on kinematics were marginal due to retention of musical performance despite fatigue. However, DAS reduced fatigue of several muscles, which is promising for injury prevention.Practitioner summary: Violinists are greatly affected by musculoskeletal disorders. Effects of a mobility assistive device on muscle fatigue during violin playing was investigated. The assistive technology slowed down the development of fatigue for three neck/shoulder muscles, making assisted musical performance a promising avenue to prevent violinists' injuries.

Perceptions of fatigue and neuromuscular measures of performance fatigability during prolonged low-intensity elbow flexions

NEW FINDINGS

What is the central question of this study? What is the predictive relationship between self-reported scales to quantify perceptions of fatigue during exercise and gold standard measures used to quantify the development of neuromuscular fatigue? What is the main finding and its importance? No scale was determined to be substantively more effective than another. However, the number of ongoing contractions performed was shown to be a better predictor of fatigue in the motor system than any of the subjective scales.

ABSTRACT

The purpose of this study was to determine the relationship between transcranial magnetic stimulation (TMS) measures of performance fatigability and commonly used scales that quantify perceptions of fatigue during exercise. Twenty healthy participants (age 23 ± 3 years, 10 female) performed 10 submaximal isometric elbow flexions at 20% maximal voluntary contraction (MVC) for 2 min, separated by 45 s of rest. Biceps brachii muscle electromyography and elbow flexion torque responses to single-pulse TMS were obtained at the end of each contraction to assess central factors of performance fatigability. A rating of perceived exertion (RPE) scale, Omnibus Resistance scale, Likert scale, Rating of Fatigue scale and a visual analogue scale (VAS) were used to assess perceptions of fatigue at the end of each contraction. The RPE (root mean square error (RMSE) = 0.144) and Rating of Fatigue (RMSE = 0.145) scales were the best predictors of decline in MVC torque, whereas the Likert (RMSE= 0.266) and RPE (RMSE= 0.268) scales were the best predictors of electromyographic amplitude. Although the Likert (RMSE = 7.6) and Rating of Fatigue (RMSE = 7.6) scales were the best predictors of voluntary muscle activation of any scale, the number of contractions performed during the protocol was a better predictor (RMSE = 7.3). The ability of the scales to predict TMS measures of performance fatigability were in general similar. Interestingly, the number of contractions performed was a better predictor of TMS measures than the scales themselves.

Determining factors for compensatory movements of the left arm and shoulder in violin playing

Introduction

Despite a large number of available ergonomic aids and recommendations regarding instrument positioning, violin players at any proficiency level still display a worrying incidence of task-specific complaints of incompletely understood etiology. Compensatory movement patterns of the left upper extremity form an integral part of violin playing. They are highly variable between players but remain understudied despite their relevance for task-specific health problems.

Methods

This study investigated individual position effects of the instrument and pre-existing biomechanical factors likely determining the degree of typical compensatory movements in the left upper extremity: (1) left elbow/upper arm adduction ("Reference Angle α", deviation from the vertical axis), (2) shoulder elevation ("Coord x", in mm), and (3) shoulder protraction ("Coord y", in mm). In a group of healthy music students (N = 30, 15 m, 15 f, mean age = 22.5, SD = 2.6), "Reference Angle α" was measured by 3D motion capture analysis. "Coord x" and "Coord y" were assessed and ranked by a synchronized 2D HD video monitoring while performing a pre-defined 16-s tune under laboratory conditions. These three primary outcome variables were compared between four typical, standardized violin positions varying by their sideward orientation ("LatAx-CSP") and/or inclination ("LoAx-HP") by 30°, as well as the players' usual playing position. Selected biomechanical hand parameter data were analyzed as co-factors according to Wagner's Biomechanical Hand Measurement (BHM).

Results

Mean "Reference Angle α" decreased significantly from 24.84 ± 2.67 to 18.61 ± 3.12° (p < 0.001), "Coord x" from 22.54 ± 7.417 to 4.75 ± 3.488 mm (p < 0.001), and "Coord y" from 5.66 ± 3.287 to 1.94 ± 1.901) mm (p < 0.001) when increasing LatAx-CSP and LoAx-HP by 30°. Concerning the biomechanical co-factors, "Reference Angle α", "Coord y", but not "Coord x", were found to be significantly increased overall, with decreasing passive supination range (r = -0.307, p = <0.001 for "Passive Supination 250 g/16Ncm", and r = -0.194, p = <0.001 for "Coord y"). Compensatory movements were larger during tune sections requiring high positioning of the left hand and when using the small finger.

Discussion

Results may enable to adapt individually suitable instrument positions to minimize strenuous and potentially unhealthy compensation movements of the left upper extremity.

Fit to Perform: A Profile of Higher Education Music Students' Physical Fitness

The physical demands of music making are well acknowledged, but understanding of musicians' physical and fitness profiles is nonetheless limited, especially those of advanced music students who are training to enter music's competitive professional landscape. To gain insight into how physical fitness is associated with music making, this study investigated music students' fitness levels on several standardized indicators. Four hundred and eighty three students took part in a fitness screening protocol that included measurements of lung function, flexibility (hypermobility, shoulder range of motion, sit and reach), strength and endurance (hand grip, plank, press-up), and sub-maximal cardiovascular fitness (3-min step test), as well as self-reported physical activity (IPAQ-SF). Participants scored within age-appropriate ranges on lung function, shoulder range of motion, grip strength, and cardiovascular fitness. Their results for the plank, press-up, and sit and reach were poor by comparison. Reported difficulty (22%) and pain (17%) in internal rotation of the right shoulder were also found. Differences between instrument groups and levels of study were observed on some measures. In particular, brass players showed greater lung function and grip strength compared with other groups, and postgraduate students on the whole were able to maintain the plank for longer but also demonstrated higher hypermobility and lower lung function and cardiovascular fitness than undergraduate students. Seventy-nine percent of participants exceeded the minimum recommended weekly amount of physical activity, but this was mostly based on walking activities. Singers were the most physically active group, and keyboard players, composers, and conductors were the least active. IPAQ-SF scores correlated positively with lung function, sit and reach, press-up and cardiovascular fitness suggesting that, in the absence of time and resources to carry out comprehensive physical assessments, this one measure alone can provide useful insight into musicians' fitness. The findings show moderate levels of general health-related fitness, and we discuss whether moderate fitness is enough for people undertaking physically and mentally demanding music making. We argue that musicians could benefit from strengthening their supportive musculature and enhancing their awareness of strength imbalances.

Differences in violin fixation force and muscle activity among violinists with and without complaints of the neck shoulder region

PURPOSE

The aim of this study is to determine the relationship between complaints of the neck and shoulder region, the jaw-shoulder violin fixation force, and the activity of the neck and shoulder muscles in violinists.

METHODS

In this case-control study twenty professional violinists were included, of which ten with current complaints of the neck shoulder region and ten without these complaints. A questionnaire including the DASH and NDI was used; violin fixation force and activity of the superficial neck muscles were evaluated in five playing conditions.

RESULTS

Each group consisted of eight female and two male violists with a mean age of 29 years. Violinists with complaints had more muscle activity of all evaluated muscles compared to violinists without complaints; complaints were significantly associated with the muscle activity of all evaluated muscles. Complaints were not significantly associated with the violin fixation force. The playing condition significantly predicted the violin fixation force and the activity of all muscles except the left mTP.

CONCLUSIONS

Violinists with complaints have more muscle activity of some superficial neck and shoulder muscles. Co-contraction is thought to play a relevant role in violinists with these complaints.

Changes in movement variability and task performance during a fatiguing repetitive pointing task

Changes in neuromuscular strategies employed with fatigue during multi-joint movements are still poorly understood. Studies have shown that motor variability of individual joints increases when performing upper limb tasks to fatigue, while movement parameters related to the task goal remain constant. However, how the inter-limb coordination and its variability change during specific movement phases with fatigue is still unclear. The aim of this study was to assess the effects of neck-shoulder fatigue on shoulder and elbow kinematic variabilities, shoulder-elbow coordination and its variability, and endpoint characteristics during different phases of a forward pointing movement. Nineteen healthy young adults continuously performed a repetitive pointing task until fatigue (Borg rating of 8/10). Changes in elbow-shoulder coordination through the movement were assessed using the continuous relative phase and statistical nonparametric mapping methods. At the end of the task, muscle fatigue was evidenced by significant increases in anterior deltoid (+13%) and biceps brachii (+30%) activity. Shoulder horizontal abduction, elbow flexion variability and shoulder-elbow coordination variability were increased with fatigue at different moments of the movement cycle (shoulder: during the first 17% and most of the second half movement, elbow: from 73% to 91%, coordination: almost the whole movement). However, movement timing errors and endpoint spatial variability were mostly preserved, even with fatigue. We showed that increased variability with fatigue is not only observed in the fatigued joint (shoulder), but also in the elbow and shoulder-elbow coordination, and may have a goal of preserving global task performance.

Fit to Perform: An Investigation of Higher Education Music Students' Perceptions, Attitudes, and Behaviors toward Health

Making music at the highest international standards can be rewarding, but it is also challenging, with research highlighting pernicious ways in which practicing and performing can affect performers' health and wellbeing. Several studies indicate that music students' perceptions, attitudes, and behaviors toward health and healthy living are less than optimal, especially considering the multiple physical and psychological demands of their day-to-day work. This article presents the results of a comprehensive screening protocol that investigated lifestyle and health-related attitudes and behaviors among 483 undergraduate and postgraduate students (mean age = 21.29 years ± 3.64; 59% women) from ten conservatoires. The protocol included questionnaires measuring wellbeing, general health, health-promoting behaviors, perfectionism, coping, sleep quality, and fatigue. On each measure, the data were compared with existing published data from similar age groups. The results indicate that music students have higher levels of wellbeing and lower fatigue than comparable samples outside of music. However, they also reveal potentially harmful perceptions, attitudes, and behaviors toward health. Specifically, engagement in health responsibility and stress management was low, which along with high perfectionistic strivings, limited use of coping strategies, poor sleep quality, and low self-rated health, paints a troubling picture both for the music students and for those who support their training. The findings point to the need for more (and more effective) health education and promotion initiatives within music education; in particular, musicians should be better equipped with mental skills to cope with constant pressure to excel and high stress levels. In part, this calls for musicians themselves to engage in healthier lifestyles, take greater responsibility for their own health, and be aware of and act upon health information in order to achieve and sustain successful practice and performance. For that to happen, however, music educators, administrators, and policy makers must play an active role in providing supportive environments where health and wellbeing is considered integral to expert music training.

Developing and validating a self-report assessment tool for software biomechanics

BACKGROUND

There are many effective methods for decreasing the likelihood of repetitive strain injury (RSI) for those who work at a computer in an office environment. This study is focused on the highly repetitive task of interpreting seismic data. The skilled geoscientists who perform this work are very well compensated, and their work is vital to the success of the oil company. However, RSIs are still occurring in situations where effective methods of mitigating injuries have been successfully implemented and this has been occurring very frequently for geoscientists. This suggests that there are other elements contributing to the development of these injuries and one element could be the software interaction design. However, it is difficult for software designers to determine this because most measures associated with muscle activity require expensive data collection methods.

OBJECTIVE

This paper describes research conducted to determine if survey-based subjective measures might be used to assess the potential for RSI for software programs.

METHODS

In laboratory and field settings, data were collected using three different survey instruments (NASA-Task Load Index, Latko's Busiest Hand Activity Level Scale, and the Borg CR10 Rating of Perceived Exertion Scale) and conventional measures of muscle activity (sEMG). Correlations between the surveys and muscle activity were then calculated.

RESULTS

For both the laboratory and the field, people were able to provide reliable self-report information related to their muscle activity. However, the effect sizes were not large.

CONCLUSIONS

These results suggest that self-report tools could be utilized to identify software interaction designs related associated with risks of RSI.

Relation between perceived effort and the electromyographic signal in localized low-effort activities

Hand-based human–machine interfaces are complex tasks that involve repetitive or sustained movements and postures of the hands that can lead to overuse syndromes of the musculoskeletal system. Consequently, it is important to minimize the physical effort that occurs at these interfaces. The evaluation of physical effort can be performed either by subjective evaluation of the relative perceived effort (e.g., Borg scale) or by objective physiological measurements (e.g., electromyography – EMG). However, the relation between these two measures has not been sufficiently studied for localized low-effort activities. This study investigated the relation between EMG and Borg ratings, as well as the issue of gender differences during low-effort activity of forearm muscles. Nine females and nine males performed eight different hand gestures (localized low-effort activity), during which EMG signals were recorded from six forearm muscles and Borg ratings were obtained. On average, the female subjects rated the gestures as less effortful than the male subjects, and also demonstrated a higher positive correlation between the EMG and Borg ratings. Furthermore, the linear model that was fitted for predicting the Borg ratings based on gender and the combined activity of muscles provided an R-squared value of approximately 0.3.

The System Usability Scale

The system usability scale (SUS; Brooke, 1996) is an instrument commonly utilized in usability testing of commercial products. The goal of this symposium is to discuss the validity of the SUS in usability tests and beyond. This article serves as an introduction to the symposium. Specifically, it provides an overview of the SUS and discusses research questions currently being pursued by the panelists. This current research includes: defining usability norms, assessing usability without performing tasks, and the use of SUS for ergonomics. In addition to this paper, there are four other papers in the symposium, which discuss the impact of experience on SUS data, the relationship between SUS and performance scores, the linkage between SUS and business metrics, as well as the potential for using SUS in test and evaluation for military systems.

Issues in relation to the repeatability of and correlation between EMG and Borg scale assessments of neck muscle fatigue

INTRODUCTION

The repeatability of subjective and objective assessments of neck muscle fatigue is very important with regard to the clinical applicability of these methods.

METHOD

To establish between-days reliability, 33 healthy volunteers performed a 60% maximum voluntary isometric contraction test from a standing position in all neck movements. Cervical muscle fatigue was assessed on three separate occasions from the spectral (median frequency, MF) and amplitude (root mean square, RMS) analysis of the electromyogram (EMG) signal recorded from the cervical paraspinal group, splenius capitis, levator scapulae and sternocleidomastoid. Subjective assessment of fatigue was rated by employing the Borg scale. Intraclass correlation coefficient ICC((1,1)), standard error of measurement (SEM), smallest detectable difference (SDD) indices and Pearson's correlation co-efficient were calculated for the analysis of the results.

RESULTS

Normalised median frequency (MF) slope had low repeatability and large between-day error (ICC((1,1))=0.28-0.61; SEM=0.33-0.60%/s; SDD=132.7-703.2%) for the protagonist muscles of each movement. Initial median frequency (IMF) had moderate to good reliability and small error (ICC((1,1))=0.64-0.81; SEM=2.8-8.8Hz; SDD=19.9-38.5%). The RMS slope yielded also poor repeatability. The Borg assessment was more reliable than the EMG estimate though variability between sessions was still quite high (SDD=29.2-136.5%). No correlation was found between the EMG and Borg assessment of neck muscle fatigue (r=-0.01-0.39).

CONCLUSION

The protocol used for assessing neck muscle fatigue proved to be reliable only for the IMF but the clinical usefulness of this measure remains questionable. The lack of correlation between objective and subjective estimation of neck muscle fatigue was possibly a consequence of the poor measurement repeatability. Further research is needed to identify the factors responsible for these results on neck area.

Effect of side dominance on myoelectric manifestations of muscle fatigue in the human upper trapezius muscle

The purpose of this study was to investigate whether differences in the peripheral and control properties of the neuromuscular system due to long-term preferential use, related to side dominance, affect postural muscles, such as the upper trapezius. Therefore, fatigability properties of the upper trapezius muscles of the dominant and non-dominant side were assessed. Surface EMG signals were detected from the upper trapezius muscles of both sides of nine right- and five left-handed subjects with adhesive linear electrode arrays consisting of eight contact points. Static constant force contractions with the arms 90 degrees abducted were performed by the subjects while holding hand loads of 0 kg, 0.5 kg, and 1 kg. Surface EMG spectral and amplitude variables were computed from the recorded signals. EMG spectral variable rate of change (indicating fatigue) showed a statistically significant difference between the two sides, with the dominant side less fatigable than the non-dominant one. The observed differences held for both the right- and left-handed subject group. A possible explanation for the results is that long preferential use of one side with respect to the other leads to changes in muscle fiber membrane and control properties, in agreement with previous results on limb muscles.

The effect of scapula taping on electromyographic activity and musical performance in professional violinists

Taping the scapula has been suggested as a method of improving both scapula position and muscular efficiency of the shoulder girdle. These factors have been linked to neck and arm problems in violinists. The purpose of this study was to evaluate the effects of taping the scapulae of violinists into a position that prevented excessive elevation and protraction whilst playing. Eight professional violinists played three different musical excerpts with and without scapula taping applied in random order. Electromyographic activity was recorded from the upper trapezii, the scapula retractors and the right sternocleidomastoid muscles. Performances were recorded onto videotape and audiocassette, and self-report data collected for later analysis. Compared with the control condition, scapula taping increased electromyographic activity in the left upper trapezius muscle during playing by 49% as an overall effect, with a 60% increase in the most physically demanding piece played. Lower music quality was detected in the same piece by raters blinded to performance conditions. Taping also had significant negative effects on subjects' reports of concentration and comfort. Short-term application of scapula taping did not enhance selected scapula stabilising muscles during playing and was not well tolerated by professional violinists.

Evaluation of physiological work demands and low back neuromuscular fatigue on nurses working in geriatric wards

This study evaluated the physiological demands and low back neuromuscular fatigue patterns following a daytime work shift of 21 female nurses working in geriatric wards. Subjects' heart rate (HR) at work was monitored for 8 h and surface electromyogram (EMG) of their back muscle was recorded during a 1-minute horizontal trunk holding test before and after work. Results showed that the nurses had heart rates exceeding 90 beats/min in 57% and 110 beats/min in 19% of their working hours. The EMG revealed a significant drop in initial median frequency (MF) (p = 0.04) and increase in negative slope of the MF/time plot (p<0.001) of the back muscle after work. These suggest that the muscles were fatigued after work. The nurses rated patient lifting, transfer and turning as most physically demanding, and these corresponded to the highest heart rates recorded. The physiological and neuromuscular strain on the nurses indicated that extreme care should be exercised at work, particularly towards the end of a work shift when the muscles have become fatigued.