Sam Curran played down any injury concerns after picking up career-best Test figures of four for 57 to help England restrict South Africa to 277 for nine on day one of the first Test at Centurion.
Curran looked to be struggling late on, seen stretching in the outfield, but said it was nothing more than a case of cramp.
"I started cramping towards the end and (Ben) 'Stokesy' was dehydrated," Curran said on Sky Sports. "It was so hot out there and there wasn't much breeze.
"It's my first time playing in South Africa and it was enjoyable."
Curran took the key wicket of Quinton de Kock for 95 and it looked like a good opening day for England after Broad removed Kagiso Rabada with the final ball.
"It's pretty even I think," Curran added. "Quinton De Kock probably got away from us a little bit too quickly but to get him out so that he couldn't bat with the tail was pretty good.
"He's one of the great one-day players and in Tests he plays his natural game. We expected him to play like that, but he got away a bit too quickly.
"We let him off the hook and he rode his luck, but fair play to him, he got a good score.
"The ball swung beautifully all day and there was a lot of carry in the wicket. We're pretty pleased.
"We want to take the last wicket as quickly as possible, then bat as big as we can and put some overs in their legs."