August 5, 2022 was a day like many others in Ukraine. First light revealed the devastation from a night of Russian bombing.

Russian attacks on a residential neighborhood of Mykolaiv that morning brought "significant destruction," the governor of the region said at the time, injuring at least 10.

On that same day, in Moscow, bureaucrats in President Vladimir Putin's office were preoccupied by an issue far removed from the brutal war in Ukraine.

"The Transportation Administration has received an appeal," a Kremlin official wrote, "about the need to install gym equipment Hoist HD-3800 and Hoist HD-3200 instead of Abductor-Standard and Abductor-Technogym in the sports-health wagon No 021-78630."

Recently leaked documents suggest that the "sports-health wagon" is used by none other than Putin himself.

Remarkably little is known about Putin's private life. His public image is carefully manicured, as has been evident in the days since Yevgeny Prigozhin's short-lived mutiny. But a trove of paperwork and photographs obtained exclusively by the London-based Russian investigations group the Dossier Center, and shared with CNN, Süddeutsche Zeitung, and German public broadcaster NDR and WDR, reveals details the Kremlin shrouds from public view, and the extent to which Putin's paranoia has created a cloistered existence.

The Dossier Center is backed by Mikhail Khodorkovsky, an exiled former Russian oil tycoon turned Kremlin critic.

The fact that Putin uses a train is well known. The Kremlin itself has released images of meetings held on board, in an ornately decorated boardroom. The contents of the train's other 20-odd cars, however, have been a closely guarded state secret.

The Dossier Center says the leaked documents came from an insider at Zircon Service, a Russian company tasked by Russian Railways, the state-owned rail operator, with outfitting the cars intended for the office of the Russian president.

Among the parts of the train detailed is car number 021-78630. A glossy brochure made by Zircon itself shows a luxurious gym and spa on wheels designed for Putin, the Dossier Center says.

The car was completed in 2018. At the time the photos were taken, it was outfitted with Italian-made Technogym weights and resistance equipment -- later to be replaced, it would seem, by Hoist machines made by a US-based company.

Through the door, further down the car, a full cosmetology center is furnished with a massage table and all manner of high-end beauty equipment -- including, according to a leaked document, a radio-frequency machine used to enhance the tautness of skin. The room itself, documents from the Dossier Center suggest, is outfitted to help prevent the use of listening devices.

Finally, a tiled bathroom features a full Turkish steam bath and shower.

Among the documents obtained by the Dossier Center are letters tying the outfitting of the rail cars, including the gym car, directly to officials at the highest levels of Putin's administration.

The Kremlin flatly denies the Dossier Center's findings, telling CNN: "President Putin does not have such a car in his use or in his ownership."

CNN also reached out to Zircon Service and Russian Railways for comment but has not heard back.

On November 2, 2018, a meeting was held to assess the work remaining to be done on the gym car, number 021-78630. The minutes of that meeting, also obtained by the Dossier Center, show that in addition to executives from Zircon Service and Russian Railways, there were 10 officials in attendance from the Federal Security Service (FSO), the organization tasked with protecting the Russian president.

Dozens of maintenance contracts leaked to the Dossier Center, some of which list the gym car number 021-78630, say that any work on the train cars must be coordinated with the FSO.

In 2020, a top official at Russian Railways, Dmitry Pegov, wrote to the deputy director of the FSO, Oleg Klimentiev, pleading with him to review proposals he had sent for living quarters to be constructed on two rail cars.

"To date, the approval of any of the options has not been received from the FSO, which does not allow us to start the procedure for concluding a contract and begin the construction of wagons," Pegov wrote. "I ask you, dear Oleg Ateistovich, to review the proposed concepts and inform us about the decision made."

CNN's attempts to reach Pegov and Klimentiev for comment were unsuccessful.

According to a former engineer and captain in the FSO, Gleb Karakulov, who defected from the country last year and was interviewed by the Dossier Center under extreme secrecy, Putin has increasingly turned to train travel as a way to avoid being tracked.

"The plane, as soon as it takes off, it immediately crosses flight radar," Karakulov said in the interview, which was recorded last December. "The train, it is used in order to somehow hide these movements."

Karakulov said that he first began working on the train, installing communications equipment, around 2014. It came into much more frequent use, according to his account, in the second half of 2021, as Russia was gearing up for its full-scale invasion of Ukraine.

According to Karakulov, Putin's train has since the beginning of the war spent considerable time parked near Valdai, a remote Russian region between Moscow and St. Petersburg. Putin maintains a large residence in the area, known for its bucolic lake and forests.

"Our employees were in quarantine specifically for this special train," Karakulov told the Dossier Center. "Since the beginning of the war, guys said that they left to somewhere in the direction of Valdai for 40 or even 45 days.

"Maybe there will be no train departure on a particular watch, but people are always ready."

Privacy, though, has not been total. The vulnerability has come in the form of amateur trainspotters.

"There is a ghost train on the railways of our country," one trainspotter wrote alongside an image of what appears to be Putin's train he posted on rutrain.com. "It is not in the timetables or in the Russian Railways systems."

They are able to identify the train in part through its use of two locomotives, and in part by a feature identified in the brochure made by Zircon Service. A characteristic white dome, said by the Dossier Center to contain advanced communications antennae, is plain to see on one of the carriages.

The domes do not appear on ordinary Russian trains. But they were visible in an official video released by the Kremlin in 2019, on one carriage of a specially-chartered Russian Railways train, as Putin rode along over the newly constructed Kerch Bridge between mainland Russia and occupied Crimea.

It is through the image of those domes that we know that Putin's train carries the ordinary external markings of a Russian train. It has been spotted -- and photographed -- repeatedly over the years by amateur trainspotters.

Trying to understand Putin's mindset is an inherently speculative affair. The best one can do is turn to those who have spent time with him.

Abbas Gallyamov is among them, having for years served as one of Putin's speechwriters.

"His feeling of political insecurity I think led to him start feeling more and more physically insecure," Gallyamov said from Israel, where he now lives. "There are a lot of people who are very close to him and who are choosing this insecurity for their own advantage, by him, look, there is a threat here, threat here, threat here."

The "paranoia," as Gallyamov describes it, has caused the Russian leader to build more and more walls around himself.

"He is losing the war, he is losing in politics, he is losing in popularity," Gallyamov says. "He is getting more and more enemies, committing more and more crimes. He feels this that he is surrounded by enemies. And psychologically he wants to feel protected against all these things."

The distance created by those protections, Gallyamov speculates, may be among Putin's most immediate problems. And, ironically, might be a reason for the extreme comforts built for his train.

"He is traveling very little," Gallyamov said. "He is losing touch with the country. People in his administration, they worry about this."

"They (officials in the Kremlin) understand that this is one of the problems which leads to a decline in his popularity. So, they are probably trying to make (things) for to him to be able to leave his residence and travel somewhere as comfortably as possible."

That approach of near-seclusion was shaken up by the short-lived Wagner mutiny. In the days following the rebellion, Putin attended an unusually high number of meetings and was even seen greeting members of the public.

It's not known whether he used his special train to get around -- but the turmoil is likely to have done little to ease his reported "paranoia."