We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
I find Deadlifts and Squats to be the most strenuous exercises. It makes sense, because these two are strength-builders - not calisthenics - and engage so many muscle groups at once. (In the Calisthenics category, I find Burpees the most strenuous.)
Squats are a fundamental, functional, whole-body exercise. As it is wrong to say that Deads can hurt your back, it is wrong to claim that squats can harm your knees. The contrary is true for both.
I focus on the squat today as I have begun to introduce weighted squats into my basic strength-building routine. I need them. Barbell on my shoulders works best for me, but to each his own. Kettlebell held on chest is good for a start.
It has taken me 11 months to get this olde corpse of mine into good enough condition to wean almost entirely off the machines and to be able to limit my strength-training with the good old basics: dumbell variations, pull-ups, bench press variations, squats, deads, and the like. (Can't do push-ups due to shoulder injury. In middle age, if one has led an active life there are always physical flaws you have to work around.)
As I have said before, my weekly 5-6 day routine includes a mix of cardio intervals, strength-building, and heavy calisthenics. It is a war against apoptosis, entropy, and Father Time. Thus it is bound to fail, eventually. Lucky for me, any issues I had with fat resolved in my first few months of training - now just the normal issues with strength and endurance that many sedentary middle-aged workers have.
For the biggest bang for your buck, the low bar back squat is the squat of choice.
I, once again, refer you to Starting Strength for the applicable chapter and verse as to why this is so.
There is no better resource for the the beginner than SS. You learn the correct way to lift, the best method to produce results and there is actual science to back it all up.
Good articles and video. I use the app Stronglifts 5x5 which uses the same lifts and principles, it adds weight automatically as you progress and if you spend the few bucks for the extras, it has warm-up sets and weight calculators. Well worth it and stupid simple interface.
My only issue with the video instruction is in his directions to breathe in when squatting down and out when standing with a heavy barbell...I believe you should fill your lungs and tense your abdominals and hold tight it for the motion and release at the top. In this way you create a solid core and stabilize your body. The only time I hurt myself was when I breathed out too soon and my lower back shifted out of alignment...several weeks of healing ensued.