Anderson bowled 29 overs in Australia's first innings - more than any other seamer - including a final spell of six overs. But rumours that he was suffering from some sort of injury continued throughout the day after he was seen grimacing just before lunch, when he appeared to take a pill brought on by the 12th man, and did not bowl immediately afterwards, with England hunting Australia's last three wickets.
But that, according to Broad, was more of a tactical issue than anything and no reflection of any fitness concerns. Anderson bowled a three-over spell with the second new ball, having delivered an initial four-over spell with the first new ball, in an attempt to ensure he remained fresh throughout the Test.
"I don't know where this mystery injury has come from," Broad said. "He's just bowled 30 overs for 50. I've spent the whole day with him and he's not moaned or said he's sore or injured. There's nothing I know about.
"Obviously it was quite hot work out there and we had to rotate the bowlers a little bit. It was a bit of a plan with Joe Root for us to bowl three-, four- or five-over spells to ensure we were always hitting the pitch hard.
"If you do get a bit tired and into your sixth or seventh over on these pitches and you float the ball up, you get hit."
Broad also offered reassuring news on Root, who sustained a crushing blow on the helmet after he was hit by a Mitchell Starc bouncer late on in the day as England battled to erase a 26-run first-innings deficit.
"It's always worrying when you see someone hit on head," Broad said. "But he's passed all the concussion tests and tests with the doc. I'm sure he'll be taking the field tomorrow fine."