>*Also was it effective?* These research studies show its effectiveness: 1. Sawashima, M., Mori, M., Nakamura, M., Yamanaka, T., & Ogiwara, T. (2002). The effect of respiratory-muscle training using a Valsalva maneuver in stuttering. Folia Phoniatrica et Logopaedica, 54(5), 242-250 2. Smith, A., Johnson, M., & Vanwynsberghe, D. (2008). Use of the Valsalva maneuver to treat stuttering: A preliminary investigation. American Journal of Speech-Language Pathology, 17(1), 88-94 3. [Here](https://www.google.com/search?q=%22stuttering%22+%22valsalva+maneuver%22+%22research%22+%22conclusion%22) are the full-versions of these research