Speech rhythm can be described as the temporal patterning by which sequences of vocalic and gestural actions unfold, within and between interlocutors. Despite efforts to quantify and model speech rhythm across languages, it remains a scientifically enigmatic aspect of prosody. For example, the existence and/or form of a basic speech rhythmic unit is hotly contested. One challenge is that the primary means of speech rhythm research has been the analysis of the acoustic signal. As speech is multimodal and motoric, investigations of speech rhythm will likely benefit from a greater range of complementary measures, including physiological recordings. The current experiment explores respiratory effort as a contributing factor in speech rhythm production. Undergoing simultaneous inductive plethysmography and acoustic recording, participants produce speech by reading novel prosaic texts aloud in single and dyadic conditions. Speech-associated breathing patterns are analysed in conjunction with traditional acoustic-phonological approaches to speech rhythm. It is hypothesized that, like spoken utterances, speech breathing is subject to rhythmic constraints. Preliminary results are therefore interpreted with a focus on the temporal relationship between inhalation events and previously proposed phonological rhythmic units (e.g., inter-stress, p-centre, syllable), underscoring breathing as a necessary, yet often overlooked, component in speech rhythm planning and production.