There’s one universally acknowledged rule all marathon runners adhere to: never do anything new or different on race day.
During training, though, it’s good to experiment and learn from your trials and errors, especially when those experiments are conducted during a long run — the bedrock of all marathon training programs that often becomes a dress rehearsal for the main event.
But what if a long run experiment is so radical that failure could jeopardize the program and threaten success on the big day?



