Over the past six months or so, in our posts about physical fitness, we have always made a distinction between strength training and the other useful activities which build strength minimally or not at all but are more maintenance-oriented and endurance-oriented such as cardio intervals, calisthenics, heavy calisthenics, high-rep weights, isometrics, pliometrics, recreational sports, or mucking out the barn. In other words, activities which use your muscles - or "tone" your muscles, but do not build them.
The latter activities so not require any more protein than one's usual diet.
Strength training is ideally part of any fitness program, but most people don't do much of it because it hurts. I am not talking about "body-building" in the extreme sense, just strength-building. Strength-building entails moving heavy things in order to break down, damage, muscle tissue. Generally-speaking, if you can do more than 12 reps you are doing a warm-up or working on endurance, not so much muscle-building so it's time to raise the weight. The strength-building part occurs during several days afterwards, the recovery phase. As with bone fractures, your body's repair leaves it stronger than it was before you broke it down.
Muscle repair and building requires more protein than the average diet, but probably not a whole lot more. There is a lot of wacky advice out there, but for those who move heavy weight two or three times/week, I think this article is reasonable: Are You Eating Enough Protein To Build Muscle?
The article claims that, for a male, a serious muscle-building program with heavy weight, 2-3 times/week, needs up to 1 gm protein/lb body weight daily. (On average, non-pregnant women have about half the dietary needs of men). It's all approximate, of course. And who knows how many grams of protein there are in my particular hamburger anyway? With a whey powder, you know what you're getting if you like that sort of thing.
(FYI, an average burger has around 20-30 gms, an egg 6 gms, a glass of whole milk about 8 gms. You can Google all food numbers. Whey powder is labeled by gms per scoop.)