Biomechanical Assessments in Woodwind Musicians: A Systematic Review

Biomechanical methods are frequently used to provide information about the kinematics and kinetics of posture and movement during musical performance. The aim of this review was to identify and analyze the biomechanical methods performed on woodwind musicians to understand their musculoskeletal demands. A systemic review was carried out following the guidelines of the document Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). It was registered in PROSPERO (code 430304).The databases PubMed, Cochrane, CINAHL, Scopus, and Web of Science were consulted between January 2000 and March 2022. The search in the databases identified 1625 articles, and 16 different studies were finally included in the review, with a sample size of 390 participants. Pressure sensors, surface electromyography, infrared thermography, goniometry in two dimensions, and ultrasound topometry in three dimensions were biomechanical methods useful to broaden the knowledge of musculoskeletal demands during musical practice. Piezoresistive pressure sensors were the most widely used method. The great heterogeneity of the studies limited the comparability of the results. The findings raised the need to increase both the quantity and the quality of studies in future research.


Introduction
Performing arts biomechanics emerged as a specialty within performing arts medicine, and it is responsible for quantifying the musculoskeletal demands of artistic tasks [1].In the area of music, instrumented biomechanical methods offer precise information on kinematics and kinetics, allowing greater insight into the movement patterns of musicians during performance [2]. This is of special relevance, considering that playing posture, repetitive movements, long study sessions, as well as the musician's own technique are risk factors for the development of musculoskeletal disorders (MSDs) related to musical practice [3,4].
Therefore, the first step for both treatment and prevention is to understand the underlying reasons and associated risk factors [5]. In this regard, the data obtained through biomechanical methods offer precise information to understand and minimize the risk of injuries [6].MSDs usually manifest as muscle overexertion, afflicted tendons, muscle tension, and fatigue [4]. In fact, musculoskeletal symptoms can range from discomfort to severe or permanent conditions that can affect the performance quality and even prevent the musician from playing [7][8][9].

Search Strategies
The PubMed, Cochrane, CINAHL, Scopus, and Web of Science databases were consulted. The database searches identified 1625 studies published from January 2000 to March 2022 using the following search strategy: (motion OR movement OR posture OR electromyography OR infrared thermography OR pressure sensors OR piezoresistive sensors OR force sensors OR three dimensional) AND (wind instrumentalists OR woodwind players OR clarinet OR saxophone OR flute OR bassoon OR oboe). A systemic review was carried out following the guidelines of the document Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [23]. It was registered in PROSPERO (code 430304).

Elegibility Criteria
Inclusion criteria were: studies that included woodwind players (clarinetists, saxophonists, flutists, bassoonists, and oboists) and that used biomechanical methods to describe kinematic, kinetic, or physiological aspects related to musicians' posture or movement. Single case articles were included since they comprised biomechanical methods used to better understand the musculoskeletal demands during musical practice, thus responding to the objective of this systematic review.
Exclusion criteria were: reviews, letters to the editor, conference abstracts, and articles published in languages other than English. Articles that did not meet the objective of the review (use of other non-biomechanical methods, analysis of movement patterns and musical expressiveness or temporal precision of the musical performance, study of respiratory parameters and anxiety) were also excluded.

Study Selection
Two reviewers independently reviewed studies for their potential inclusion against the eligibility criteria. Any disagreement was resolved by arbitration of a third reviewer.

Data Extraction
Two reviewers retrieved the data independently. Data extraction was carried out using a single form with the following information: first author and year of publication, characteristics of the participants (number of subjects, age, gender, state of health, type or group of musical instrument, occupation (professional, student, amateur) and years of practice), biomechanical methods, objectives, musical activity, other evaluations (nonbiomechanical), results, and conclusions.

Quality Assessment of Included Studies
The studies included were assessed for quality using the checklist Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) [24]. The STROBE statement is a checklist of 22 items considered essential for the proper communication of observational studies [24].

Selected Studies
After the removal of duplicate records, a total of 1447 were reviewed screening titles and abstracts. Of these, 1417 articles were excluded because they did not deal with the subject studied. For example, studies on airflow measurement, reed vibration, geography, and protein were excluded. Finally, 30 were deemed to warrant full-text evaluations. After analysis of the remaining 30 studies, 16 articles met the inclusion criteria and were included in this review ( Figure 1).

Selected Studies
After the removal of duplicate records, a total of 1447 were reviewed screening and abstracts. Of these, 1417 articles were excluded because they did not deal wi subject studied. For example, studies on airflow measurement, reed vibration, geogr and protein were excluded. Finally, 30 were deemed to warrant full-text evaluations analysis of the remaining 30 studies, 16 articles met the inclusion criteria and we cluded in this review ( Figure 1).

RIP
Higher chest cavity expansion standing (p < 0.01) and lower abdominal cavity expansion in sitting postures (p < 0.01). Lower activation in seated postures in comparison to standing posture (p < 0.01).
Significant differences in respiratory mechanics between sitting and standing postures. 2D Goniometry SEMG Analyze the relationship between body posture, muscle activity, and sound quality.
Playing a 60-s musical excerpt in two different postures (habitual sitting posture and experimental sitting posture).
Not carried out.
Smaller low thoracic angle, smaller high thoracic angle, and larger pelvic tilt angle in the experimental posture (p < 0.001). More activity of the erector spinal and lower trapezius muscles and less activity of the left upper trapezius and right brachioradialis muscles in the experimental sitting posture.
Postural exercise therapy may change muscle activity patterns. Before and after playing a musical piece ("Vingt Etudes") for 10 min.
Questionnaire (musical and clinical history of the participant) and clinical examination.
Statistically significant differences (p < 0.05) between before and after musical in the left temporal muscle, orbicularis muscle, perioral teguments, and teeth 11 and 21. Asymmetries ≥0.3 • C in the temporal and the orbicularis muscles at rest position and after the musical performance.
IT has been proven to be an effective complementary diagnostic tool in the monitorization of the CCMC. Pressure sensors Quantify the pressure applied to the central incisors during embouchure.
Playing three times three different pitches (high, medium, and low).
Clinical and radiographic examination.
Greater force was applied during lower-pitched notes, especially to tooth 11 (108 g). Pressure: performing three times three different pitches (high, medium, and low). IT: before and after using an occlusal splint during 6 months.
Clinical examination.
Higher pressure in higher pitches (94 g in tooth 11 y 408 g in tooth 21). Thermic difference between left and right side of the masseter muscle of 0.7 • C before and 0.3 • C after the use of the splint.
Pressure sensors and IT are useful in the diagnosis and monitoring of TMDs. 10 Clemente et al.
(2019) [26] Pressure sensors Quantify the applied forces of the perioral structures during embouchure.
Playing three times three different pitches (high, medium, and low).
Not carried out.
Brass players apply greater force than woodwind players during embouchure.  Playing a musical piece and two scales Not carried out.
Significantly higher facial muscle activity in students. 17 Gotouda et al.  Determine the impact of the neck strap on thumb force while measuring the thenar, cervical, and shoulder muscle activity.
After playing a set of exercises during 3 min with and without a neckstrap.
Perceived effort survey using a scale from 0 (no effort) to 5 (severe effort).
Non-statistically significant increases in the muscle activity of any muscles of the neck, the shoulder, or the thenar muscles with the neck strap (p > 0.05). Significant decrease in average thumb force with the neck strap (p < 0.05).
The use of a neck strap significantly decreases the average force of the right thumb.
In previous reviews, Herrmann et al. [6] identified quantitative studies involving biomechanical assessments in brass players, while the reviews by Kelleher et al. [1] and Schemmann et al. [5] identified the biomechanical assessments in strings musicians (violinists, violists, cellists, and double bass players). To our knowledge, this is the first systematic review conducted solely on woodwind musicians to identify and summarize findings on biomechanical methods.

Pressure Sensors
According to the findings of this review, kinetic analysis was based on the measurement of finger force while fingering [37], the force of the right thumb while supporting the weight of the instrument [33], and, more frequently, the force exerted by the musculature that participates in the embouchure [26][27][28][29][30][31]. The clarinet was the most frequently tested instrument, appearing in six of the eight studies that used pressure sensors [26][27][28]31,33,37].
There is great heterogeneity in the included studies, which makes it impossible to compare the results. For example, various studies measured the force exerted by the upper incisors in single-reed instruments (clarinet and saxophone) [26,27,29,31], but no uniformity was found regarding the best location for the sensors, which must be superimposed so that they occupy the upper surface of the mouthpiece of the instrument. In this way, the same incisor could be exerting pressure over two different sensors. Moreover, two studies measured the lower lip force during embouchure [26,28], but the number of participants was very small, and none accurately described the musical task. As for the double-reed instruments (oboe, English horn, and bassoon), the researchers measured the pressure exerted by the upper and the lower lip [26,30], but the number of participants for each of the instruments considered was very small.
Therefore, due to the small number of studies, the small number of participants and the scarce methodological information (such as information referring to the characteristics, calibration, and location of the sensors or the musical task performed), as well as the lack of uniformity expressing the measurement units (Newton or grams), the results cannot be compared to reach conclusions. Despite this, pressure sensors have been shown to be useful as a complementary diagnostic tool in four studies [27,[29][30][31] according to various pathologies: apical lesion [29], malocclusion [27], and TMD [30,31].
Additionally, only one study measured the force exerted by the fingers during fingering, using special ring-shaped force sensors [37], and another study measured the right thumb compression force exerted to hold the instrument using a piezoresistive sensor [33]. In both cases, the chosen instrument was the clarinet. Although the right arm and hand in woodwind players are the most frequently injured body parts due to the weight bearing of the instrument [8], only two of the studies evaluated the finger force during performance [33,37]. This finding could lead future research to contribute to increasing the number of studies.
The research demonstrated that pressure sensors allow quantifying the force exerted, improving the understanding of musculoskeletal demands during the execution of the instrument. They are also useful as a complementary test for the diagnosis of disorders of the orofacial musculature and TMJ.
The studies showed that SEMG could quantify the activity of a large variety of muscles under different conditions, although only one study [32] examined a group of musicians that had reported a pathology (specifically pain in the TMJ and jaw muscles). Thus, the studies considered in this systematic review sustain important methodological differences that limit the comparability of the results. For example, two of the studies analyzed the activity of the masseter muscles [32,36]: the first one [36] evaluated the activity in the right side of the face in a group of healthy clarinetists that played a musical piece and two scales, whereas the other study [32] involved a larger group of participants consisting of various woodwind and brass specialties, with pain in the TMJ and jaw muscles, playing a specific pitch, a pitch one octave higher and a repertoire of 90 min.
In accordance with the aforementioned, wind musicians may present muscular hyperactivity due to the effort exerted by the perioral structures during embouchure [13,25]. Similarly, the muscle activation patterns of the upper extremity have also received interest from researchers. In this regard, a review by Overton et al. [17] on evidence of electromyo-graphic muscle activity in the neck, shoulder, and spinal musculature of musicians found conflicting evidence that related pain to an increase of the muscle activity in the neck and shoulder musculature (upper and lower trapezius, upper cervical extensors and sternocleidomastoid muscle). The researchers concluded that further studies were warranted to better understand the relationship between pain and muscle activity in musicians [17].
Another aspect of EMG to highlight is the possibility of biofeedback, a process in which, while the musician performs, he can graphically see the behavior of his musculature and make corrections of an incorrect technique [16], favoring the reduction of muscular tension or better performance [41]. None of the studies included in this review used EMG biofeedback.
Finally, it should be noted that there was only one study [33] that simultaneously applied the two most widely used methods according to the findings of this review. These are SEMG and pressure sensors. Therefore, it would be advisable to carry out more research that analyzes the musculoskeletal demands during musical performance through the analysis of muscle activity patterns with SEMG, combined with the quantification of force with pressure sensors, either while supporting the weight of the instrument or during the embouchure, in order to establish possible correlations.

Infrared Thermography
IT was the third most used method, and all the studies evaluated the thermal patterns of regions of the cranio-cervical-mandibular complex (CCMC) [25,27,30,31,39].
The included studies demonstrated that IT is useful for the assessment of CCMC regions [27] and as a complementary tool for the diagnosis of malocclusion and TMD [30,31]. However, the number of participants was very small. In addition, due to the scarce methodological information, the results cannot be compared. It should also be added that none of the studies considered applied IT to assess areas of the body other than those of the CCMC. Future research could use IT as a complementary test to diagnose other pathological conditions, such as inflammatory diseases, overload, and muscle fatigue, in other body regions, such as the upper extremity.

Kinematic Studies
Kinematic studies for the assessment of posture and movement [35,40] were the least frequent. One research conducted a three-dimensional analysis with UT in saxophonists [40]. Another study used two-dimensional goniometric analysis to evaluate the sitting posture in clarinetists [35], but the research did not specify which program was used.
An earlier review by Schemmann et al. [5] identified two studies that combined UT and SEMG in violinists. Additionally, Kelleher et al. [1] concluded that one of the most commonly used methods to analyze movement in string musicians (violinists, violists, cellists, and double bassists) was photogrammetry, which captures movement using cameras and reflective markers. However, according to the findings of this review, no study used photogrammetry to analyze movement in woodwind players.

Implications for Future Research
There is great heterogeneity in the studies included in this review. Furthermore, due to the scarce number of participants and the lack of methodological information, the results cannot be compared. Additionally, the small number of studies found for each of the biomechanical methods instills the need to increase both their quantity and their quality in future research. This may have important implications in the treatment and prevention of injuriesor MSDs related to musical practice, as well as in artistic performance.
All of this could allow us to achieve a methodological standardization that would take into account the biomechanical method used, the musical instrument played, and the pathology, if applicable. For example, the most convenient way to place the pressure sensors in the embouchure could be to establishor determine which muscles should be evaluated to discover their activation patterns based on a certain pathology or MSD.

Conclusions
Pressure sensors, SEMG, IT, 2D goniometry, and 3D UT are biomechanical methods useful to broaden the knowledge of musculoskeletal demands during a musical performance. A Piezoresistive pressure sensor is the most widely used method.
The studies included in this systematic review were very heterogeneous and few. For this reason, it is difficult to compare their results. Instead, itis necessary to increase the size and quality of research in this area for better knowledge of the musculoskeletal demands of woodwind musicians and thus be able to develop strategies for the prevention and treatment of injuries or MSDs related to musical practice.