Suddenly my thighs ignite in violent tremolando. Up until now I had been sitting on what felt like a normal exercise bike. But now I am wobbling more than I have since leading the school orchestra's second violin section in "Schubert's Symphony Number 8".
A vibrating exercise bike is an intriguing concept, which, I later learn, is designed to "engage your core muscles". To my relief, the seat remains static, but the pedals vibrate as if they are wired to a jackhammer.
The powerBIKE is a new product from the people behind the popular Power Plate – an exercise platform that vibrates at various speeds, adding considerable intensity to stretching and other floor exercises. The bike, the Power Plate people say, combines all the benefits of the plate (improving muscle tone and bone density, for example) with the cardiovascular workout of an exercise bike.
It is certainly hard work. The harder you push, the faster the pedals vibrate, rotating the wheel in a jagged circle. I am told it is a little like cycling over cobbles, but having never got round to learning to ride an actual bike – I accidentally sacrificed my childhood on the altar of Nintendo – that sensation is alien. I have wheeled a cheap barbecue over a slatted wooden boardwalk, however, and the memory instantly returns.
Rebecca Romero, one of Britain's many Olympic cycling gold medallists, who also has a silver medal in rowing, has been testing the bike. She warms up with 30 minutes on the top intensity setting. On this level, I am exhausted after around 40 seconds, but the lower ones are more manageable.
Vibrating exercise technology has been around for about 30 years, but only in the mainstream for five or six. It was originally used by Soviet cosmonauts in preparation for space missions. In zero-gravity conditions, muscles waste away alarmingly quickly, just as rested limbs do after injury or surgery. In this regard, the Russians fared far better than the Americans.
"When you walk down the street, and you step on an uneven paving stone, your muscles contract" explains Lars Harms, Power Plate's UK academy and education manager. "If they didn't, you would fall over and injure yourself. By exercising on an uneven surface, you are activating those core muscles. It makes everything that much more intense."
Intensity, it seems, is the name of the game. Sessions on the powerBIKE should be kept to no more than 30 minutes, but those minutes are the equivalent of far longer on one of those old fashioned, non-vibrating machines. It is all about the "HIT" – high-intensity training – the current buzzword in fitness circles. Idly pedalling on an exercise bike, reading the paper or watching the news does not deliver the HIT, failing to activate and exercise the crucial fast twitching white muscle fibres of which Lance Armstrong and Usain Bolt have more of than most.
At £2,995, the powerBIKE is not cheap. And don't expect one to appear in your gym any time soon. The company intends at first to integrate them with existing Power Plate classes. For the moment at least, a normal exercise bike is far cheaper, and most should fit on top of a standard tumble dryer.
* Researchers at UCL are developing implantable chips capable of exercising paralysed people by sending electronic impulses to the spine.
* The £6,000 Xdream bike is part exercise bike, part video game. Users race around simulated routes, complete with potholes.
* Jukari "Fit to Fly" classes urge people to swing from a trapeze to improve strength and balance.