The thing is, 5X5 should be done at about 80-85% of 1RM, right?
Who says? Really! There's no such rule. You should be training at weight that you find challenging, and that's within a range that you can handle, and progress in. If you're hitting near your 5RM for 5x5, how is that better than hitting near your 1RM for singles? Every set should leave something in the tank! Especially at "our age"!
that's what I make of the "one rep max calculator" in this very site (sorry, I'm not allowed to include links) . There are two issues for me here, the first is wether the table holds for all ages - judging by my own experience I doubt that it does as my 5RM is lower than that, but maybe it's just me, not my age. That's an example of tha data I'm looking for as stated in my first post on this thread, and it's important as I try to avoid trial and error here, because an error might have undesired consequences (plus a long healing time...).
No! You don't need that data. It's all wrong. There is nothing universal about the rep-max calculators or about the "strength standards" tables. A bunch of high school football players, or whomever Mark Rippetoe used to come up with that table (which he has since, as I recall, regretted making) aren't like you in any way. The calculators are a very rough approximation at best, way off at worst. It has to do with age, it has to do with ratio of slow-twitch to fast-twitch muscle fibers, it has to do with your training history, it has to do with your parents, it has to do with the phase of the moon and how you hold your tongue. Calculators are pretty useless, at least for what your trying to use them for. All that counts is your own experience. An error that's very far on the high side might have the consequences you fear, but an error on the low side will only mean that you are building experience, learning a movement, learning good form, and slowly starting to add strength. What's your deadline here? Is there some hurry? I doubt it. For me, the deadline is death. I suspect that that is still a few years away, so I'm not going to hurry much. Don't be in a hurry.
The second issue is that whatever precent of my 1RM they are, the resistance I need for 5 reps, if I want to feel I am really working, are exerting too much strain on my joints (pushing only, there seems to be no such problem with pulling), so I tend to do 10-12 reps with lower weights, even at the price of not getting to the optimal training for strength or hypertrophy.
Again, why do you feel so locked in to 5 reps?
Because you read it somewhere? Did the author know you?
Because some trainer at a gym said do 5x5? How does he know?
Do you have any idea how little training and experience most "personal trainers" have? How much time do they spend reading? How much experience do they actually have? How well have they studied, analyzed, tested you? How much do they know about training older lifters? There is nothing special about 5 reps or about 5x5 training! Nothing. 5x5 may be right for someone, somewhere, at some point in his training, but isn't right for very many people, very much of the time. If what you are doing is hard on your joints it's wrong for you, no matter who said you should do it.
Volume will kill your joints much faster than intensity will. If doing 5 reps at a weight that you consider "really working" makes your joints worse, then don't do it. It's not complicated. If this exercise is making you worse instead of better, don't let some snot-nose kid at your gym control your life (or whoever says you should do it). You know your body. Now you need to get to know your body exercising. If 5x5 at this weight is hurting your joints, then try 3x3. Don't worry if the weight is too low to be "optimal for strength or hypertrophy". That's not what you need right now, you don't need to gain strength or hypertrophy as fast as anybody else, or even at all at first. You need to be comfortable lifting the weight, or doing whatever exercise you are doing. So what if you're not stronger by next week, or next month, or even next year? You will start gaining strength at the right time for you. Again, what's the deadline? If you don't get good at just doing the exercises, you'll never get stronger without injury. I know a real smart guy, whom I won't name here lest it set off a flurry of posts, who advises beginners, or even experienced lifters who are starting a new lift, to do something that he calls the "honeymoon period" when they lift weights for a few sets of 3 at light weights. They can add a little weight to see how it feels. If it gets too heavy, they learn to feel it. They can go back down on the weights as needed. No pressure, almost no risk of injury. Then, when they get comfortable, and they have an idea how much they can lift, they settle on a reasonable number of reps and sets, and not in the 5-10 range usually. 3x3 or 3x4 is not bad. You can increase that as you go along until you learn what's good for you.
People who advocate using a 5x5 routine as a beginner (in any of it's expressions) usually advocate only varying one factor, the intensity, or loading. So you do 5x5, (for some that means 2 warm-up sets of 5 and then 3 work sets of 5, some 5 sets of 5 work reps). If you complete all the prescribed reps, next workout you add a prescribed amount of weight to the bar (5# or upper body, 10# for lower is common), and do 5x5. If you can't complete those reps, then you have a certain number of workouts in which to make them. If you can, you again increase the weight and try 5x5 again. If you can't make the reps within a prescribed number of workouts, you "reset" the weight to something lower (20% is commonly used) and then repeat the process. Usually you'll get back up to the neighborhood you were in last plateau, maybe a little higher, then plateau again. So you repeat until you make some criteria that they set for changing to their periodized program. The real reason for the plateaus was not, as they probably told you, that you are now an intermediate lifter, and you can't stimulate adaptation enough in one workout without outstripping your ability to recover. The reason is that you've been trying to add workload faster than you can possibly increase your strength. Adding 5 pounds to 25 reps is a huge increase in work. Once you are near your threshold, you can't possibly keep doing it. And since these programs only tell you one way to progress, you're stuck. Plateaued again.
So my bottom-line advice, is take it way easier than you have been taking it. Find a moderate rep-set scheme and weight that you can handle, then increase things by small steps. Add a little weight sometimes, add a rep or two sometimes. If you're having a bad day and your joints hurt, don't be afraid to back off a little. It's not the end of the world if this workout doesn't look as good on paper as your last one. It can still me just what your body needed this time.
Having said that, I think I will stick to the advice I got some days ago, which will also make Nike happy, meaning stop blabbering and and just do it. Pull ups, here I come.
That takes us back to where you really are right now. You commented that your loading on the barbell is so low that you are ashamed to say what it is. That makes my rant steam start building pressure again, and it's too late at night for that. Who are you lifting for? The kids at the gym? The guys here on the forum? Hopefully not. Hopefully you are lifting for you, and you alone. What does it matter to anyone how much you can bench, press, squat or deadlift? If you can't do any of those things with a little weight on the bar, then you aren't ready for them yet. Pull ups are a great exercise! If you can't do any, or only one or 2, then use the assisted pullup machine or stretch bands so you can get a bit of volume. Do pushups. Study pushups and learn to do them well. Don't try to go for max per set. Do several sets with appropriate rest in between.
Squat. Yes, I said squat. Right from the beginning, but not with added weight. Do body weight squats until you can do them really well, good and deep, back in good position, knees not TOO far over your toes, knees aligned with toes. All body weight only. (I mean your body without added weight, not a barbell on your back that weighs as much as you do.) Google "Dan John Squat" and find the video of him teaching squat to a group. It's terrible quality video. It's not on YouTube, but on one of the other video sharing services. Do his "potato sack" squats. When you're really good at all the variations, then get a 5 pound dumbbell and clutch it to your chest, and start doing goblet squats. Once you are doing them with dumbbells that are hard to handle, start thinking about barbell squats.
Do inverted rows, or machine rows, some sort of horizontal pulling movement. Start easy. Take the row on a honeymoon, and get to know her (it?) for a life-time relationship. You don't have to get the most out of it right away!
Learn about swings and pull-throughs and step-ups. Same approach on them. Have a nice long honeymoon with them before you start deadlifting.
Do "core" work. Pallof "press". If I just got you doing these, this rant would be worth the effort. Try them. And planks, side planks, bird-dogs, etc. No crunches or situps. At our age we've already used up most of our allowed lumbar flexion-extension cycles, and can't afford to waste any on such silly exercises.
Ok, I'm out of rant. Done. Good luck.