This study compares speaking rate in spontaneous speech between dysarthric and healthy speakers. Since dysarthria involves heterogeneous pathologies, two types of dysarthria (i.e. Parkinson's disease and amyotrophic lateral sclerosis) have been distinguished. We hypothesize that temporal organisation of speech may be different between healthy and dysarthric speakers, but also between both pathological populations. Four measurements have been explored. Results show that Parkinsonian speakers are characterized by a short Inter-Phrasal Unit (IPU) while word duration is similar to healthy speakers. Amyotrophic Lateral Sclerosis speakers produced long words while IPU duration is similar to healthy speakers. Number of words per IPU distinguishes healthy speakers from dysarthric speakers while number of syllables per second separates Amyotrophic Lateral Sclerosis speakers from Parkinsonian speakers. These results suggest that the boundary between pathological and healthy speech should be examined with multidimensional analyses.