Strengthening the diaphragm, abdominal and intercostal muscles through resistance training (Respiratory Muscle Training, or RMT) leads to increased lung capacity and maximum phonation time – an important parameter for singing. Strengthening the respiratory muscles using resistance training can help improve engagement of the main (diaphragm) and accessory breathing muscles, thereby improving airflow control, phonation, and ventilatory control, promoting increased quality of voice production. Several studies have demonstrated benefits of RMT in professional singers and instrumentalists. However, most focused on uni-directional RMT (inspiratory or expiratory only), and none studied cRMT with highly-trained singers.
Objective: To document the effects of cRMT in a highly-trained population of professional singers. Methods: Study participants (N=18), many of whom are currently singing in major international houses, were randomly divided into control and intervention groups. The intervention group engaged in six weeks of cRMT. Changes and benefits of the training were tracked by singer self-assessments, and pre- and post-study recordings were evaluated by expert listeners. Data Analysis: The main goal was a comparison of the control group to the intervention group. It is assumed that participants treated the Likert scale similarly regardless of group. This was tested using an F-Test to justify Two-Sample Equal Variance T-Testing.
Next, intervention group comparison of pre and post cRMT protocol survey responses was taken by the same overall method of F-Testing and Paired T-Tests. The application of a Chi-Squared to these characteristics was also used along with Student’s T-Test. This shows the statistical significance of change within the intervention group. Last, intervention group to control group comparison was made using Two-Sample Equal Variance T-Test, F-Test, and Chi-Squared Test. Significance for all tests was p < 0.05. Results: After cRMT protocol, values moved towards Disagree with descriptors that would hinder easy vocalization (pressed, over-engaged, etc.) and towards Agree with positive descriptors (resonant, easy, free,etc.) Conclusions: Based on the self-assessment survey data analysis, our research supports the claim that opera singers perceived an improvement in singing experience after six weeks of cRMT in the following areas: Easier breath flow, greater ability to inhale deeply, increased awareness of pelvic floor, smoother upper passaggio, more resonant lower tones, tone spinning more consistently, singing legato felt easier, less pressed phonation, and less over-engagement of abdomen. These data support the supposition that cRMT is beneficial to highly trained classical singers.