Are There Differences in Abdominal Muscle Function in Female Singers With and Without Voice Disorders? - An Observational Study

Abstract

The purpose of this study was to determine the motor function of the abdominal muscles in singers with and without functional voice disorders and to examine them for possible differences. Additionally, the breathing behaviour and posture control was investigated. Observational study. Female subjects (n=20) with differing levels of professional competence were used to provide the data for analysis. By using the Singing Voice Handicap Index (SVHI) the grade of dysphonia could be measured, and the subjects were organized in groups. The change of muscle thickness of the M. transversus abdominis (TVA) and the M. obliquus internus abdominis (OIA) during different singing tasks was measured by using ultrasound. The subjects were then asked to perform the Abdominal Hollowing Test (AHT) with the STABILIZER. Finally, the subjects were all filmed while singing. The videos recordings of the singing sessions were analysed by an independent clinical expert regarding breathing and secondary motor activities (SMA). For the statistical analysis, the Mann-Whitney-U Test and the Chi-Square-Test was mainly used. The results showed a significantly thinner TVA in the group with dysphonia in comparison to the group without dysphonia. Ultrasound measurements showed significantly higher changes of muscle thickness of the TVA during singing tasks in the group with dysphonia. Regarding the AHT there was a significant difference between the two groups. The group with dysphonia was not able to increase the pressure by 15mmHg. Furthermore, the healthy subjects demonstrated abdominal breathing, while the group with dysphonia present with thoracic breathing. Additionally, it was noted that the subjects with dysphonia showed a higher level of associated movements especially at and/or on the lumbar spine, cervical spine and the left arm and shoulder. Differences in TVA-recruitment, breathing behaviour and secondary motor activities while singing were found. This study sparks new ideas for neuromusculoskeletal assessments and therapy.