On the April 13 broadcast of SBS' 'Kim Young Chul's Power FM', Heechul explained his reason for not promoting with the rest of Super Junior as they've recently made a comeback with "Lo Siento".
He said, "As 'Knowing Brothers' viewers are aware, I don't participate in any physical game. The hyungs are very considerate in that they tell me I don't need to do anything that'll put too much burden on my body and that it's okay since I talk well."
"Originally, I wasn't supposed to go on any music program starting from 'Sorry Sorry'. At the time, I was so touched by the rest of my members that I promoted with them, but it ended up making my body worse so it was decided that I wouldn't promote during 'Black Suit'. However, because so many members were enlisted, I thought to myself that I needed to participate in 'Black Suit'. Now, I believe I should just not do it altogether if I can't do it wholeheartedly," he explained.
Heechul lastly added, "Thankfully, whenever I speak to Lee Soo Man teacher, he asks if my leg is okay and that I need to be careful. He also tells me to get my treatments and rest when I need to."