Nature will find a way if it has enough room for trial and error. Say, millions of germs mutating inside millions of hosts using antibiotics, trillions of mutations trying to beat a single molecule. By the time the Cretaceous environment recovered, birdosaurs could not regain their place on the top of the food chain because that space was taken over by mammals.
So if the extinction is swift and massive enough, the ecosystem will shift and there will not be a way to be found. So you should always ask: what dreadful bloodsucking beasts will replace the mosquito ?
I would much rather prefer they breed a transgenic mosquito unable to spread dengue than try to wipe all mosquitoes off the face of the planet.
If you are squatting heavy, as you should be doing if you are training with the goal to increase your overall strength, walking up a couple floors shouldn't be too hard of a task and I am pretty sure there are more benefits to it than it would hurt your other goals.
I remember a blog entry that I most likely found here.
It was from a company owner who makes the rules which determine how he pays employees public to everybody.
It seemed pretty fair and according to him he hasn't had any complaints so far.
I will keep looking for it as it was a good read, maybe somebody has it bookmarked though.