K Shredprotein and complex carbohydrates. Avoid fatty foods before and after your training, but make sure that you eat healthy vegetable fats in moderate amounts every day. Mistake 6 - Poor Technique One of the most frequent causes of sports injuries is the wrong posture during the exercises performance. The first thing you need to master at the gym is the correct technique, especially when it comes to such exercises as barbell squats, deadlift, and bench press and, of course, other exercises both at the gym and outdoors.