To increase muscle size and strength, you must tax your muscles heavily enough during exercise that they sustain small amounts of damage, which the body then repairs, making the muscles larger and stronger than before. A hard set is one set of repetitions of an exercise that fatigues your muscles and pushes them to the very limits of their capability, often known as the “failure” point. When performing a hard set, it is important to follow some safety precautions to avoid injuring yourself.
Many exercise enthusiasts who want to build larger, stronger muscles do two or three hard sets scattered throughout a workout, but not enough to cause injury and with enough time in between to facilitate a partial recovery. Others may perform only one hard set per workout in order to train the muscles without the risk of overtraining. Most people who are serious about building muscle usually try to do multiple hard sets to achieve the maximum amount of fatigue throughout all of the muscle fibers.
To do a hard set, first determine the number of repetitions, or reps, you wish to complete per set. Most women and a few men try to do 12 to 15 reps per set to tone and tighten muscles without building them larger, but for a hard set it is probably a better idea to aim for a maximum of eight to ten reps, possibly fewer. Next, select the amount of weight you need to lift to reach your muscles' failure point by the last few reps. A regular set may get tougher toward the end, but you can, without too much strain, reach your repetition goal. During a hard set, you should really be struggling and almost unable to lift the weight at the end.
Make sure you are practicing proper form for the exercise you are doing, and use a spotter when weightlifting to avoid serious injuries. Spotters can be very important during a hard set, because since you are trying to push your muscles to failure, you may accidentally drop the weight or be unable to lift the weight off of yourself. Additionally, properly warming up before exercising, especially when you plan to do a hard set, can mean the difference between tiny beneficial muscle tears that cause muscle hypertrophy and a large, painful, debilitating muscle or tendon rip.