I am "training" for a hypothetical 1/2 marathon (I have not yet actually committed to any marathon). I cannot run on the advice of surgeon who did my hip replacement. My walking speed has increased from a 20-minute mile to an 18-minute mile. I am NOT confident that I can get much beyond this.
In my training, I am up to walking 8 miles this week. Up until now, my longest walk has been 85 minutes. I figure that 8 miles will take me about 2.5 hours.
Here is my question - is there a minimum speed that one needs to walk to engage in a 1/2 marathon? If so, what is it?