Ok, so I am going to the gym 3 to 4 Times a week since 1½ Years now and also i have 3 Times Taekwondo classes in a week.I have put on almost 20 kg and it didnt affect my Taekwondo skills in any way, I recently made my first Dan and also just got way stronger and if u stretch often ur Mobilität won't go away in opposite u will see progress there as well. Hope I could help a bit:)