Okay...
After teaching 3 kettlebell classes and 6 taekwondo classes today, I return to find my post has some interest.

Sorry if you think that my clients question was stupid. I guess I am in the business of answering stupid questions sometimes. I believe that the client wanted to know either (A) his perceived effort on the ropes for 0:15 seconds versus a certain distance in sprinting...or (B) Maximal Oxygen Consumption (VO2 Max) equivalence of 0:15 of ropes versus X meters in sprint.

Obviously, the answer to A is up to each individual. Having trained in undulating rope techniques for a little while, I would say the rope is more challenging than sprinting. The answer to (B) seems quantifiable and that was the answer I was seeking.

Britt...thanks for getting my back.