The following is an excerpt from International Fitness Model/Exercise physiology student @kilbnation "The amount of misleading information in the fitness industry is baffling. By far the biggest myth (in my opinion) lies within the misconception of reps and their relative results. For example the squat challenge. This “challenge” has you performing 100-250 reps per set… So many people correlate this type of muscle burn with “ripped/toned” results. This is not true! This type of training targets muscular endurance, a system that does NOT grow muscle mass (women… do not let “muscle mass” scare you off). This is sometimes tough to understand as a set of 100 reps will still exhaust you (though the resistance you’re placing on your muscles is not enough to stimulate an increase in tissue size). It is critical that you understand; YOU CAN NOT TONE YOUR MUSCLES. Muscle tissue either grows or shrinks. Once they grow (through the correct rep range) you need to lose the body fat so your muscles have less fat tissue covering their natural curves (creating that “toned” physique). So in conclusion… This routine targets a cardiovascular/muscular endurance workout. You sacrifice growth for a mediocre at best cardiovascular workout. Instead, target your sets for 8-12 reps; this rep range is most efficient for muscle growth (consistently supported through credible research) and stick to a more intense cardiovascular routine (like HIIT training). AND WOMEN if you think this rep range is going to turn you into a man, you might as well call your gym and cancel your membership. It takes a LONG time for your muscles to grow. You can easily monitor your muscle mass by adjusting the rep/weight range during the coming months. Note: I am not suggesting you stop physical exercise, just trying to help you find a program that will better meet your needs.