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.

Q: Randomized trial of 20-week aquatic classes .

A: not found
****
Q: Lack of blinding as a result of different treatment schedules may have confounded results .

A: not found
****
Q: In a 2 week randomized two-period crossover trial , 18 male adolescents consumed two diets , named white diet ( WD ) and brown diet ( BD ) , which were poor and rich in MRP , respectively .

A:
18 male adolescents
****