Hypertrophy training is training for the goal of increasing the size of your muscles, by expanding the cross-sectional size of the tissue (20).
Two factors contribute to hypertrophy:
Sarcoplasmic hypertrophy
Myofibrillar hypertrophy
Sarcoplasmic hypertrophy relates to increases in fluid, giving you the appearance of larger, puffier muscles. This fluid portion contains water, minerals, glycogen, and phosphates and comprises nearly 80% of total muscle mass.
“Myo” is from the term Greek mys, and refers to muscle. Myofibrillar hypertrophy relates to increasing myofibril size, or the size of your muscle fibers - this is the type of hypertrophy many strive for when looking to gain strength and size.