In medical studies, treatments are tested within a group of study participants. You will be given a sentence of a study report in which your task is to list the phrases that give information about the participants of the study. You should list the phrases in the same order that they appear in the text, separated by commas. If no information about the participants is mentioned, just output "not found". Relevant information about participants include: gender, medical conditions, location, number of people participating. Do not contain participant mentions without relevant information.
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Question: The question of whether abstinence during the months following a planned quit attempt exacerbates or improves depressive symptoms is an important clinical issue .

Answer: not found


Question: Constant exhalation may therefore be a useful alternative to the breath holding technique for clinical measurement of TLCO .

Answer: not found


Question: To study the effects of physical exercise on biochemical risk factors for ischaemic heart disease 31 healthy middle aged men undertook regular physical exercise for two months and 29 served as controls in a randomised trial .

Answer:
31 healthy middle aged men