Muscle function has been used to measure the healthy and functional capacity of patients, sportsmen and athletes. The knowledge about muscle function and how to properly evaluate it can be determinant factors for the success of therapies during the treatment of many diseases, as well as improving muscle performance. Handgrip strength is a measure of maximum voluntary force of the hand. It has been reliable, valid and an objective parameter to evaluate overall muscular strength, and for this reason, it has been used as a predictor of physical disability. There are several techniques to treat and rehabilitate muscle function such as the proprioceptive neuromuscular facilitation technique (PNF), functional training and traditional muscular strengthening. Physical exercises produce unquestionable health benefits, and when used properly, physical exercise can treat or become an adjuvant therapy for many diseases such as cancer, diabetes mellitus and patients with chronic heart failure. In addition to all the health benefits of exercise, new techniques of rehabilitation and the improvement of muscle performance were included in this book through the use of muscle strengthening associated to technological therapies, such as phototherapy (laser and light-emitting diodes), for muscle repair and performance. During your reading, this book will provide you with concepts, techniques and new perspectives about physical exercises that will become differential knowledge for health professionals to treat patients and/or make champions using powerful tools: physical exercise and technology.