One set per body part workouts, sometimes called the single set system or high intensity training — HIT for short — are brief but intense workouts where each training set is performed to the point of failure. Reaching failure means you cannot complete any more repetitions without assistance. Popularized by fitness authors Arthur Jones, Ellington Darden, Mike Mentzer and Matt Brzycki, HIT workouts offer a viable alternative to higher-volume training systems.
Author and bodybuilder Mike Mentzer, in his book "Heavy Duty," states it is not the volume of exercise that triggers increases in strength and muscle size but the intensity of the workout. Mentzer goes on to say that if intensity is sufficiently high, then volume must be low, and one set taken to failure per body part is ideal. Mentzer's methodology is echoed by inventor of Nautilus strength training equipment Arthur Jones. Jones performed a number of studies and found that a single set of sufficiently high-intensity strength training produced significant increases in strength and muscle size.
Ellington Darden, author of "The New High Intensity Training: The Best Muscle-Building System You've Never Tried" suggests that to get the most from single set per body part training, exercise selection is important. According to Dr. Darden, you should select exercises that use a large amount of muscle mass and involve the movement of multiple joints at the same time. Bench presses, squats, dead lifts, shoulder presses and pull/chin-ups are all favored in HIT workouts. By utilizing a large number of muscles at the same time, you promote the release of essential anabolic hormones that are vital for increasing strength and muscle mass.
HIT Advantages and Benefits
A typical HIT workout consists of between six to 10 exercises. Only a single set of each exercise is performed, so workouts should take no more than 30 minutes. The brevity of an HIT workout makes this style of training ideal if you are busy and have little time to train. As you are only performing a single set, it's easy to track your progress in terms of weights lifted or repetitions performed. HIT workouts are conducted at a rapid pace with minimal rest between exercises, so there is a resulting cardiovascular training effect. This effect, termed “Metabolic Conditioning” by author Matt Brzycki, means you get aerobically fitter despite not performing any cardiovascular exercise.
Working out to failure is an intense experience physically and psychologically. There are no easy workouts with HIT training. Because of the significant buildup of lactic acid and the ever-present need to improve your lifting performance, HIT training can be uncomfortable, as it requires you to push your muscles as hard as possible. Training to failure can be dangerous — if you fail to complete a repetition or perform your final reps using less than perfect lifting techniques, you may suffer an injury. Performing a single exercise per body part also means there will be little variety in your workouts.
Although HIT training calls for one work set per body part, it is important to warm up thoroughly to minimize your risk of injury. Perform some light cardio and stretching before lifting any weights, and then perform one or two light sets of each exercise to fully prepare your muscles and joints. Strive to beat your previous workout by lifting more weight or completing more repetitions every time you hit the gym.