Attach a large fan to treadmills, stationary bikes and rowing machines which blows air towards the user. This will provide a more realistic simulation of the actual activity, speed-based resistance, and cooling to the user.
This seems to be such an obvious idea that it must exist in the real world or in another idea here, but I can't find it, so please excuse me if I'm covering old ground.-- Srimech, Dec 02 2008 Oh it exists. It was the practically the sole source of resistance back before magnets became commonplace in such devices.-- Texticle, Dec 02 2008 Magnets, so that's how they work! I don't believe I never realised that.-- Germanicus, Dec 02 2008 I know fans as a source of resistance exist. Rowing machines still use them, so far as I can tell. I just haven't seen one that intentionally blows onto the user.-- Srimech, Dec 02 2008 To make it more realistic you could add some falling leaves or swooping angry birds.-- penguin_tummy, Dec 03 2008 They are still the resistance method of choice for all 'good' rowing machines (there are overpriced crap ones that use a stirrer in a pool of water), and give a similar feel to that of the real thing. The air 'pumped' through the fan is usually exhaused into the atmosphere around the fan, some of which reaches the user. Unfortunately, because the wind is undirected and allowed out in all directions, there isn't much to be felt. The wind should also come from behind for rowing, as you face backwards. I'd like to see a rower including ducting to give a 'wind' from behind, but it would be extremely bulky.
The problem I see with using the resistance to produce 'wind' is that you'd need to put the user effectively into a wind tunnel unless you used a power supply to boost the fan to provide the necessary velocity.
I like the idea of walking into a gym with a howling gale coming from all the cardio machines!-- Skrewloose, Dec 03 2008 For a backward-blowing draft on a rowing machine, you could just extend the chain, looping back under the machine to a fan at the back.-- Srimech, Dec 06 2008 random, halfbakery