This was reported by RIA Novosti with reference to the press service of the supervisory agency.
"According to preliminary information, on June 18, a 26-year-old man died in the pool area in a fitness club located in Mikhailovsky Proezd," the message says.
The prosecutor's office intends to establish all the circumstances and reasons for the incident.
Also, prosecutors will assess compliance with the legislation in the field of services provided.
In April, a man was shot dead in a gym in Moscow.