Protein Supplementation Augments Muscle Fiber Hypertrophy but Does Not Modulate Satellite Cell Content During Prolonged Resistance-Type Exercise Training in Frail Elderly.

In frail older adults, resistance training is required to realize the muscle and functional health benefits from dietary protein; taking protein supplements without resistance training does not improve strength, muscle mass, or physical performance unless their usual protein intake is less than 0.8 grams per kilogram of body weight per day.

In frail elderly people who do resistance training, increases in the number and size of nuclei within muscle fibers are linked to muscle growth, and this growth occurs primarily through the increased activity of existing nuclei rather than the addition of new ones.

In frail older adults around 77 years old, taking 30 grams of milk protein daily while doing supervised strength training for 24 weeks results in a 23% increase in type I muscle fiber size and a 34% increase in type II muscle fiber size compared to those who do not take the protein supplement.

In frail elderly individuals, taking protein supplements while doing resistance training for 24 weeks does not increase the number of satellite cells or myonuclei in muscle fibers, even though the muscle fibers grow larger.

In frail older adults who perform resistance training for 24 weeks, the amount of muscle tissue each existing nucleus supports increases in both slow-twitch and fast-twitch muscle fibers, whether or not they take extra protein, and no new nuclei are added.

In frail older adults, resistance training alone shows a small, non-significant increase in fast-twitch muscle fibers, while adding protein supplementation results in a measurable increase in both slow-twitch and fast-twitch muscle fibers.