Training through pain is never the intention and it will get you nowhere in the long run. It is not worth doing the exercise if you know in advance that it will cause you more problems. So make sure the complaints you have remain acceptable. To make this more understandable, we often use a pain score. When you score the pain on a scale of 0 to 10, you can score a maximum of 3 for the complaints you are experiencing at that moment. When it is a 6, 7, 8 or higher you know you are doing something wrong! This also applies to the reaction of the knee AFTER the training. If you get up the next day and have more complaints than the day before then you know that you have to adjust something in your training. Sets, repetitions, weight, exercise choice are all variables that you can adjust.