The 27-year-old centre-half missed virtually the whole of last season with knee problems but he has played every game in the league so far - including three in eight days.
"I went through three games in just over a week with t
he Brighton, Southampton and Norwich matches and came through it fine," Coles told the Evening Post.
"My fitness felt good after the Norwich game - I probably felt better than I did after the Brighton match.
"If I'm fit, I'll always want to play and I've got no worries about playing three games in a week any more. I don't want people to be worrying about my knee because I know I can play three games in a week. It's not an issue for me now.
"I didn't train until Thursday last week and had a few days off, but I kept my fitness up in the gym. My knee feels absolutely brilliant so with a full week of training ahead, I'll be ready for the Southend game on Saturday."