Well, Nadal and Ferrer are maybe the 2 men's players most renowned for their tireless energy and unlenting grinding style. They run and run forever when required, digging for shot after shot. They like getting their opponents in long rallys and wearing them down if possible. I think Maria is suggesting that that particular style between those two would be entertaining to watch in a Bikram Yoga setting where temperatures are over 100 degrees. Definitely a test of endurance.
But maybe not that much different than a typical match at Melbourne during a really hot summer day with the roof open.