The Russian leader whose image of physical vigour is key to his success has cancelled several foreign trips in recent weeks and has rarely left his suburban residence outside Moscow.
A respected Russian newspaper claimed Thursday that a publicity stunt in which Putin tried to lead cranes on their migratory paths in a motorised hang-glider aggravated an old injury.
Putin's office denies it was the flight with cranes, insists it is just a pulled muscle and spins the situation, saying that athletes often get banged up.
Besides, it says, Putin's avoiding the Kremlin office so he doesn't tie up Moscow traffic with his motorcade - something that hasn't seemed to trouble him during his previous 12 years in power.
So what's really wrong?
Combine the old Russian custom of keeping a leader's health problems secret with a massive PR apparatus that micromanages information about Putin to the nth degree and what do you get? A lot of speculation.
After celebrating his 60th birthday in early October, Putin has rarely left his official residence, sparking claims that illness or injury had laid him low.
On Thursday, the Vedomosti daily cited unnamed Kremlin-connected sources as saying Putin's September flight with the cranes had aggravated an old injury.
Putin spokesman Dmitry Peskov told a state news agency that Putin had pulled a muscle during a workout, but it was not connected to the highly publicised flight.
"Indeed, he pulled a muscle," Peskov was quoted by RIA Novosti as saying. "Actually, we have never tried to conceal it because any athlete has lots of injuries, which, however, do not mean any restrictions of his activities."
By writing off the injury as a sport-related trauma, Peskov apparently aimed to reinforce Putin's image of vigour and daring - a persona he has assiduously cultivated since coming to power in 2000.
State television has shown him swimming in a Siberian river, petting a tranquilised polar bear in the Arctic and piloting a fighter jet, as well as skiing and practicing judo.
The hang-glider flight with the cranes, which took place just before a summit in Vladivostok, was one of Putin's trademark adventurous media events.
Yet on the first day of the summit, Putin did seem to be in discomfort as he greeted leaders and avoided standing for long periods of time.
Peskov was quoted as saying that Putin was making only infrequent trips to the Kremlin lately because he didn't want his motorcade to disrupt Moscow's notoriously bad traffic.
Putin's motorcade does force the shutdown of large stretches of highway, an inconvenience that many irritated drivers mark by blaring their horns angrily as the presidential car races past.
Putin has also put off several expected trips abroad, including ones to India, Turkey and Bulgaria.
The Interfax news agency cited Peskov as saying there was no single reason behind those changes.
Despite the cancelled trips, Putin is still shown on state television almost daily - mostly sitting at meetings with officials.
A Moscow-based political analyst said the health problems of Russian leaders in the past have often led to political crises.
"First of all, it slows everything down. Even the most immediate problems or solutions cannot be taken and they have to be delayed," said Viktor Kremenyuk of the US-Canada Institute.
"There is no mechanism to replace the president in the absence of the president. This simply means a standstill - everything stops."
Putin's macho image is especially important in Russia, which has often been ruled by aged autocrats whose health was routinely kept a top secret.
Russians often ascribed Boris Yeltsin's disjointed speech and bizarre behaviour to heavy drinking, although his press service insisted he was taking strong drugs to alleviate a heart condition.
Soviet dissidents once ridiculed the mumbling and senility of Leonid Brezhnev, who led the Soviet Union until his death in 1982 at age 76.
Two more aged Soviet helmsmen died after Brezhnev in just three years before Mikhail Gorbachev took over in 1985 - prompting Russians to joke about "season tickets" to their funerals.
Dictator Josef Stalin's death in 1953 came as a surprise to average Soviet citizens although his health had been deteriorating for years.