Weight training aims to build muscle by prompting two different types of hypertrophy: sarcoplasmic hypertrophy and myofibrillar hypertrophy. Sarcoplasmic hypertrophy leads to larger muscles and so is favored by bodybuilders more than myofibrillar hypertrophy which builds athletic strength.
Firm and toned upper arms can make the difference between a fit upper body and a flabby one. According to the American Council on Exercise, strength training defines, tones and improves muscular strength and endurance. For the best results, do resistance training on nonconsecutive days and perform high reps with limited rest between sets for a calorie-burning boost. If you are new to exercise or have a medical condition, consult a physician before beginning a new routine.