Nod. There's one time runners *need* to have lane restriction: when racing. At other times, those mighty athletes can go around.

I would seriously complain to the gym management pointing out that you were staying *in* lane, and if they'd wanted you to change *which* lane, a simple "Walkers, could you please move to the outer lanes? We're using the inner lanes for training. Thank you!" would have been a hundred times more appropriate.