“…resistance training increases muscle strength via hypertrophy of muscle fibers or neural recruitment of In older adults, increases in strength also have been related to reversal of fast-twitch fiber atrophy. 65 Muscle hypertrophy occurs after puberty, when increased levels of hormones such as testosterone, growth hormone, and other growth factors are present. 62 Muscle hypertrophy is seen in adults when high levels of resistance are used.…”