Coulson arrived shortly thereafter, changing into sweats and a tshirt and likewise going barefoot. It had been years since he'd sparred with Natasha - probably not since before the Avengers and the Battle of New York. He was older now, which meant he might be a bit slower, but he was also training more.. And well, the arm Fitz had built him had quite a few new features that might just be able to throw Natasha for a loop.
His rubbed at the metal band where the prosthetic met flesh as he made his way out into the training room, smiling at Natasha. "Been waiting long?"