Physical stress is known to affect speech in many ways. To investigate this area, foreign researchers usually use medical, acoustic or statistical approaches. This paper examines the impact of physical stress on speech from the phonetic point of view. The study includes collection of speech data, namely speech produced before and after performing a physical task. Speech of eight people was recorded. Then, a threestep analysis (auditory, acoustic and statistical) was conducted. The auditory analysis revealed various mistakes' occurrence, which can be attributed to the fact of the reader's distraction. The results of the acoustic analysis have shown that there is dependency between the values of the acoustic parameters and the fact that a sample of speech was produced under physical stress. It is particularly evident in terms of the fundamental frequency and the phonemes' duration. This study also considers the intensity of breath to be an important parameter of speech produced after performing a physical task.