Dolphins players said they have seen the effects of the heat on opposing players, one glaring example coming in 1997 when Colts quarterback Jim Harbaugh asked out of the game in the second half because he kept cramping.
Tackle Mark Dixon also saw it in the Seattle Seahawks two seasons ago when the Dolphins blanked them 23-0 on opening day.
"After the first three or four plays, you could tell," Dixon said. "Their body language. They were just shaking their head; if the ball went away, they were not chasing it. The way they were standing in the huddle. Most of the time, by the third or fourth quarter you can see it. But usually you can tell early they're gassed."
The Lions have taken a lot of measures this week to try to deal with the heat. For example, Coach Marty Mornhinweg had the heat turned up in the team's practice bubble the first three days of the week, reaching a heat index of 93.5 degrees.
Mornhinweg said he might have followed the normal routine, where teams usually fly into town the day before the game, had Detroit's second game of the season not been at Carolina, where the weather also could be a factor.
"I talked to our trainers, our strength and conditioning coaches, our doctors, an ex-professor of mine at Texas-El Paso. I talked with all of those people and came up with a plan," Mornhinweg said. "I feel we'll be prepared for the heat and humidity."
Mornhinweg's efforts are all well and good, but residents of Miami will tell you, you don't get acclimated to this type of weather in a week.
Said Dolphins coach Dave Wannstedt: "We work in it year-round. We started getting ready for it in April. It's not as much the heat as the humidity. That's the big difference. That's what makes you sweat and drains your body."