No. This shows Leg Master® is doing its job! Any new exercise will tire the muscles it targets. If you don’t normally use those muscles, then exercising them will make them ache. The natural process of strengthening will take place over time. Let your body give feedback on when to take it easy. Aching muscles during and after exercise is a good sign. It means the LegMaster® has targeted hard to reach muscles you haven’t been able to work. Your strength will increase and the aches should be much reduced as your core muscles become stronger.