I hear "I'm 50, I can't build muscle" from patients every week. So I tested it on myself. 12 weeks, 2x/week, 4 exercises: goblet squats, dumbbell bench, seated rows, overhead press.
Dexa scan before and after: 3.1 lbs lean mass gained. Waist down 1.5 inches. Resting heart rate 68 to 64. The key was progressive overload — adding 2.5 lbs every week, not just going through the motions.
Protein at 1.2g per kg of body weight. Sleep 7+ hours. Nothing fancy. At 50, you can still build muscle. It's just slower — about half the rate of a 25-year-old based on the literature. But it works.
I'm now training 3 clients over 50 using the same protocol. All 3 gained at least 1.5 lbs of lean mass in 8 weeks.