Intramuscular Oxygenation and Muscle Activity of Extensor Carpi Radialis Brevis During Piano Performance: An Observational Study.

BACKGROUND: Repetitive piano movements have been associated with playing-related musculoskeletal disorders (PRMDs) such as forearm myalgia and symptoms of lateral epicondylopathy. Despite the high prevalence of PRMDs among pianists, there is poor understanding regarding the underlying physiological mechanisms. Intramuscular oxygenation may play a role in the development of PRMDs. Therefore, this observational study aimed to explore the effect variability of playing piano repertoire on the oxygenation of the extensor carpi radialis brevis (ECRB). METHODS: Surface electromyography (EMG) activity and intramuscular oxygenation data (using near-infrared spectroscopy, NIRS) of the left and right ECRB were recorded in 13 conservatory piano students (8 female, 5 male, mean age 23.54 ± 3.24 years) while playing piano repertoire (virtuoso piece or études) for 20 minutes. From the oxygenation data, relative changes (in the percentage of the baseline measurements at rest) were calculated. RESULTS: For all participants, the oxygenated hemoglobin of the left ECRB over the piano play presented an averaged decline to the baseline resting value, with a sample mean for left ECRB of -7.48% and -11.88% for the right ECRB, ranging from -15.53% to -2.00% and -19.12% to -3.93%, respectively. The deoxygenated hemoglobin ranged in the left ECRB from -5.39% to 39.14% and from -9.37% to 54.01% in the right ECRB. The change in total hemoglobin ranged from -5.35% to 16.80% for the left ECRB and -12.10% to 10.37% for the right ECRB. EMG activity (in % maximal voluntary contraction) presented a mean of 16.85% (range 11.86 to 24.43) for the left ECRB and 23.65% (range 14.46 to 37.91) for the right ECRB. This pilot study presented a Pearson's r between the averaged oxygenated hemoglobin and EMG of -0.60 for the right ECRB and -0.48 for the left ECRB. CONCLUSION: Piano performance induced an average decline in oxygenated hemoglobin in the left and right ECRB, which differed largely between the specific pieces played. The EMG activity can partially explain these differences. Further research is needed to explore the impact of a 'dynamic index' reflecting the piece's dynamic characteristics and the individual oxygenation characteristics.

Effects of Rehearsal Time and Repertoire Speed on Upper Trapezius Activity in Conservatory Piano Students.

BACKGROUND: Repetitive piano play may overload neck and shoulder muscles and tendons, leading to playing-related musculoskeletal disorders (PRMDs). METHODS: In this pilot study (EMG data of the extensor carpi radialis have been published separately), surface electromyography (sEMG) activity of the upper trapezius (UT) was captured in 10 conservatory piano students while playing a fast and a slow music score selected from the individual's repertoire, each 3 minutes long. Measurements were made at baseline and again after 2 hrs and 4 hrs of rehearsal time of the piano études. The amplitude of the sEMG signal was processed by a smoothing algorithm, and the frequency component with a non-orthogonal wavelets procedure. Amplitude of the sEMG was expressed in percent of maximal voluntary contraction (%MVC) at baseline, and the frequency component using median frequency based on the frequency band powers. Statistical analysis encompassed repeated measures ANOVAs for the amplitude and frequency components of the sEMG signal (set at 5%). The students also rated the intensity of rehearsals using a visual analog scale (VAS). RESULTS: The median values for the %MVC presented a global mean for the left trapezius of 5.86 (CI90% 4.71, 6.97) and 5.83 for the right trapezius (CI90% 4.64, 7.05). The rehearsals at moderate intensity increased the amplitude of %MVC of the upper trapezius by around 50% and decreased the median frequency. CONCLUSIONS: Playing faster presented higher magnitudes of activity of the upper trapezius. The decrease in the median frequency in response to long rehearsals may be a sign of muscle fatigue.

Effects of Rehearsal Time and Repertoire Speed on Extensor Carpi Radialis EMG in Conservatory Piano Students.

BACKGROUND: Repetitive actions while playing piano may overload forearm muscles and tendons, leading to playing-related musculoskeletal disorders (PRMDs), including lateral epicondylitis. METHODS: In this pilot study, surface electromyography (sEMG) activity of the extensor carpi radialis (ECR) was captured in 10 conservatory piano students while playing a fast and a slow music score selected from the individual's repertoire, each 3 minutes long. Measurements were made at baseline and again after 2 hrs and 4 hrs of rehearsal time of the piano études. The amplitude of the sEMG signal was processed by a smoothing algorithm, and the frequency component with a non-orthogonal wavelets procedure. Amplitude of the sEMG was expressed in percent of maximal voluntary contraction (%MVC) at baseline. Statistical analysis encompassed 2-way repeated measures ANOVAs for the amplitude and frequency components of the sEMG signal (a set at 5%). The students also rated the intensity of rehearsals using a VAS. RESULTS: The ECR presented with a mean amplitude of 23%MVC for the slow scores, which increased significantly to 36%MVC for the fast scores. The sEMG signal presented a significant though small decrease of 1.9%MVC in amplitude between baseline and 4 hrs of rehearsal time and no shift in frequency, which may indicate that the rehearsals were held at a physiological steady-state and suggesting optimization or complementary muscle loading. CONCLUSIONS: These data accentuated that the loading of the ECR (as reflected in the amplitude component) was higher than that seen for computer keyboard workers. The augmented loading of the ECR and reduced blood flow to forearm muscles may be a factor in the development of PRMDs in pianists.

Questioning the "SPIN and SNOUT" rule in clinical testing.

Specificity (SP) and sensitivity (SE) answer the question 'what is the chance of a positive or negative test in response to the presence or absence of a clinical condition?'. Related to SP and SE are the diagnostic procedures of SNOUT and SPIN. SNOUT is the acronym for 'Sensitive test when Negative rules OUT the disease', SPIN for, 'Specific test when Positive rules IN the disease'. SE and SP are incomplete because for clinical diagnosis, the question of concern should actually be: 'what is the chance that the clinical condition will be present or absent in the context of a positive or negative test result?'. The latter statement is related to the concepts of Positive and Negative Predictive Value (PPV and NPV). However, PPV and NPV are predictive values not only dependent on SE and SP but also largely dependent on the prevalence in the examined population. Consequently, predictive values from one study should not be transferred to some other setting with a different prevalence. Prevalence affects PPV and NPV differently. PPV is increasing, while NPV decreases with the increase of the prevalence. This makes prevalence the nemesis in the application of the predictive values. Therefore, another variable has been introduced to evaluate the strength of a diagnostic test, namely the likelihood ratio. Likelihood ratios determine how much more likely a particular test result is among people who have the clinical condition of interest than it is among people who do not have the condition. LIKELIHOOD RATIO (LR) is the ratio of two probabilities. This letter illustrates the limitations of the concepts of SE, SP, NPV, PPV and the LRs in context of specific shoulder tests.

Walking with robot assistance: the influence of body weight support on the trunk and pelvis kinematics.

PURPOSE: The goal was to assess in healthy participants the three-dimensional kinematics of the pelvis and the trunk during robot-assisted treadmill walking (RATW) at 0%, 30% and 50% body weight support (BWS), compared with treadmill walking (TW). METHODS: 18 healthy participants walked (2 kmph) on a treadmill with and without robot assistance (Lokomat; 60% guidance force; 0%, 30% and 50% BWS). After an acclimatisation period (four minutes), trunk and pelvis kinematics were registered in each condition (Polhemus Liberty [240 Hz]). The results were analysed using a repeated measures analysis of variance with Bonferroni correction, with the level of suspension as within-subject factor. RESULTS: During RATW with BWS, there were significantly (1) smaller antero-posterior and lateral translations of the trunk and the pelvis; (2) smaller antero-posterior flexion and axial rotation of the trunk; (3) larger lateral flexion of the trunk; and (4) larger antero-posterior tilting of the pelvis compared with TW. CONCLUSIONS: There are significant differences in trunk and pelvis kinematics in healthy persons during TW with and without robot assistance. These data are relevant in gait rehabilitation, relating to normal balance regulation. Additional research is recommended to further assess the influence of robot assistance on human gait. IMPLICATIONS FOR REHABILITATION: The trunk and pelvis moves in a different way during walking with robot assistance. The data suggest that the change in movement is due to the robot device and the harness of the suspension system more than due to the level of suspension itself.

Trunk kinematics during walking in persons with multiple sclerosis: the influence of body weight support.

BACKGROUND: Although body weight supported (BWS) treadmill training (TT) leads to some improvements in walking ability, it has not been proven that it is more effective than other walking therapies in persons with multiple sclerosis (PwMS). One possible explanation could be that BWSTT focuses on the cyclic movement of the lower extremities while the trunk is passively suspended in the harness. OBJECTIVE: This study aimed to assess the 3 dimensional trunk and pelvis movements during BWS treadmill walking. METHODS: 14 PwMS and 14 healthy persons (8 male/20 female; age 23 to 59 years) walked with 0%, 10%, 20%, 30%, 50% and 70% BWS. After a familiarization period, kinematic electromagnetic tracking (Polhemus Liberty™ 240/16) of the trunk and pelvis movements was applied. Statistical analysis consisted of a repeated measures ANOVA with simple contrasts (SPSS 20). RESULTS: This study shows that BWS walking leads in general to smaller maximum trunk and pelvis movement amplitudes compared with walking without BWS, this with exception of the pelvis anterior-posterior movement in healthy subjects. CONCLUSION: These data help to identify and isolate the effect of different BWS levels in PwMS and in healthy persons and suggest to use BWS lower than 30% for treadmill training.

Trunk muscle activity during walking in persons with multiple sclerosis: the influence of body weight support.

BACKGROUND: Although the trunk is important for maintaining balance during walking only very limited information about the trunk muscle activity during walking with body weight support (BWS) is reported in literature. OBJECTIVE: The aim of this study was to measure the effect of BWS on the trunk muscle activity during treadmill walking. METHODS: 14 persons with multiple sclerosis and 14 healthy persons walked on a treadmill with 0%, 10%, 20%, 30%, 50% and 70% BWS. Bilateral EMG measurements (surface electrodes) on the m. rectus abdominis, m. obliquus externus, m. erector spinae and m. multifidus were performed. The maximal muscle activation was presented as a percentage of a performance related reference contraction. A repeated measures ANOVA with simple contrasts was applied (SPSS20). RESULTS: In general when comparing walking with BWS with walking with 0% BWS there is an increase in m. obliquus externus activity and a decrease in back muscle activity. With increasing percentages of BWS an increase in activity of the abdominal muscles and a decrease in back muscle activity was found, with most changes in high percentages BWS. CONCLUSION: Based on the results, it is recommended to decrease the percentage BWS as fast as possible beneath 30% BWS.

Walking more slowly than with normal velocity: The influence on trunk and pelvis kinematics in young and older healthy persons.

BACKGROUND: Few studies have addressed trunk and pelvis movements during gait, although they play an important role in gait control. The aim of this study was to compare trunk and pelvis kinematics between slower walking (1, 2, 3, 4kmph) and normal walking (5kmph), and between healthy adults who were young (n=15, 20-30years) and older (n=17, 50-60years). METHODS: After 4min of treadmill walking, the 3-dimensional trunk and pelvis kinematics was measured (Polhemus Liberty™, 250Hz). A repeated measures ANOVA with simple contrasts was used to look for differences between the velocity conditions of walking and independent t-testing for comparison between the age groups (significance level: 5%, SPSS20). FINDINGS: Walking more slowly than with normal velocity induces (1) a decrease in vertical center of mass of the trunk displacement, trunk lateral flexion and axial rotation and pelvis lateral and antero-posterior tilting, and (2) an increase in lateral and antero-posterior center of mass of the trunk displacement. Compared to young persons, older persons show: (1) larger pelvis axial rotations and trunk lateral and antero-posterior movements, and (2) smaller pelvis lateral tilting and trunk vertical movements and rotations. INTERPRETATION: The literature reports that patients often walk slowly and that older persons show different gait patterns compared to young persons. This study shows that there are changes in trunk and pelvis kinematics (1) when walking more slowly than with normal velocity and (2) in older persons compared to young persons. These data could be taken into account in gait rehabilitation.