...Will have to figure out other ways to get my heart high so I can emulate running intervals....
How about indoor rowing
....in the winter? And outdoor single sculls
on the Potomac in the summer?
For those of us that cannot run to achieve anaerobic conditioning, rowing is a great alternative. Good worldwide age-group competition
on-line, inexpensive once the initial investment is made, and the machine folds up and stows very conveniently in less than a minute.