Kenya, renowned for its distance runners, has faced frequent allegations of doping, with some 40 cases reported in the past four years.
The International Olympic Committee (IOC) said last month that competitors from Russia and Kenya, given the recent history of doping in both countries, would have to be screened individually before being allowed to participate in the Rio Games next month.
Rosa, who runs Italy-based Rosa & Associati, "conspired to cause injury by doping, to the reputation and profession of athletes," according to a police request submitted to court to extend Rosa's detention for questioning.
The affidavit, signed by Police Chief Inspector Joseph Indeke and presented to a Nairobi court, also accused Rosa of "preventing some of them from their lawful exercise of their profession" due to doping.
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"The respondent in furtherance of unlawful purpose, resulted in the ban of some athletes from participating in international competitions and others even becoming incapacitated," the affidavit said.
Coach Berardelli was also detained and questioned on allegations including that he "conspired to cause injury by doping, to the reputation and profession of athletes," according to an affidavit by Chief Inspector George Mutiso submitted to court.
Neither Rosa nor Berardelli were charged and were not required to enter a plea. The magistrates approved their continued detention for questioning.
Rosa's lawyer, who objected in court to his client's continued detention, could not be reached for further comment. Berardelli's lawyer confirmed his client was detained until Tuesday but gave no further details.
Neither Rosa nor Berardelli could immediately be reached for comment.
The affidavits did not name any athletes. Those who have been managed by Rosa & Associati include former Boston City Marathon and Chicago Marathon winner Rita Jeptoo, who failed an out-of-competition test for the banned blood-booster EPO.
Jeptoo was also coached by Berardelli.
Kenyan President Uhuru Kenyatta signed an anti-doping amendment bill into law after the World Anti-Doping Agency (WADA) said Kenyan legislation passed in April needed further changes to comply with WADA's code.
(Reporting by George Obulutsa, Humphrey Malalo and Isaack Omulo; Editing by Edmund Blair and Ken Ferris)
