Speech rhythm varies with age. In this paper, we examined the role of mean and peak syllable intensity variability in age-related rhythmic changes. Sixteen younger adults and 10 older speakers read 60 sentences in Zurich German. Results revealed that peak syllable intensity variability is significantly smaller in older compared to younger adults; there was no such effect for syllable mean intensity. Reduced fluency, changes in the biomechanical properties of articulators controlling the mouth opening cycles, and compensation strategies for subglottal pressure generation were the most plausible reasons for the obtained age-related syllable intensity variability.