Just both of you do a 200 meter sprint then immediately commence sparring to replicate the crossing of a battlefield.
I doubt I would too to well personally in a fight right after a 200 meter sprint or a half hour of grappling, but with all due humility I regularly beat people who are in much better shape than I am. For one thing, being overweight doesn't necessarily mean you are weaker. I'm stronger than most people I spar with, and that helps to whip out hard fast strikes.
For another thing, training and experience can trump physical conditioning, though ideally it is far better to have both.
You can see an example of this in the clips I uploaded a few weeks ago of the match I had with the escrima guy. He was much faster on his feet than I am, in much, much better shape, but I was able to defeat him about 80% of the time due to having more experience with my weapons, and initially, due to his weapons (escrima sticks) being too short to cope with WMA weapons.
That match was a good example of the dynamics of this. We were at it for almost 45 minutes, almost continuously. We did little groups of 5 -10 sparring rounds followed by a brief pause to switch-up weapons or discuss the fights. By about fifteen minutes I was totally winded, but I was able to keep getting kills. I did suffer several setbacks though. I had to generally concede the initiative, and either try to catch him with a quick counter as he darted in and out of range, or move forward to try to corner him into a fatal engagement, usually with a bind and strike.
Toward the very end I also found that some guards were difficult to maintain, and that i had to forgoe some opportunities for strikes which were too ambitions, especially complex feints whcih I could normally get away with, I knew I just didn't have the energy for.
On the other hand I did find that my exhaustion (you can hear me breathing very hard in most of the clips) kind of reached a plateau after a while and I was able to keep going a lot longer than I first thought.
I have had many matches like this, needless to say, though this one was particularly intense due to being a kind of a grudge match. I'm used to the other guy being faster on their feet. In general though, against a less skilled but physically more conditioned opponenet, superior timing, better grasp of reach and range, and skill at parrying will still win the day, but a fast runner could easily escape me!
Anyone wishing to put my theories on this to the test is of course invited to try sparring with me during Southern Knights <img src="/forum/images/icons/wink.gif" alt="" />
JR