I'm kind of in the same ~~boat~~ erg as you. I've been doing 5/3/1 for a couple of years now, and just took up rowing this winter. I've been running Pete's Plan. I'm still doing the 5/3/1 main lifts (with a little reduced volume), but instead of the accessory work, I row. I lift first, then row, then some stretching. So far, it's working for me.
Given your age (i.e. our ages), you'll want to read The Barbell Prescription. Check out the chapter on conditioning; they do an excellent comparison of running, treadmills, rowing, etc, vis-a-vis aging knees and other body parts.
Get a copy of Sullivan & Baker's Barbell Prescription. It contains an excellent and detailed treatment of how to teach elderly and frail people how to squat. It includes many layers of, "OK, if she can't do that, here's something else to try".
Seriously, get the book and read that chapter. I've never seen a better treatment of this exact subject.
Give him Sully's book. He may not listen to you. Maybe he will listen to a doctor.
Disclaimer: I'm not a doctor. I'm just some guy on the internet who (literally) feels your pain and is willing to share my story.
Yeah, this sucks. I've had similar problems. About 10 years ago, I had an acute episode of lower back pain (as in, sudden excruciating pain that almost made me pass out). A course of oral steroids helped a bunch, but I was still getting some spasms. An MRI showed a bulging L4-L5 disk.
Physical Therapy helped some more. Or, maybe not. It's hard to tell if the PT actually did anything, or if it was just passage of time. I'm pretty sure the alternating hot/cold, and the electro-stimulation was all just BS (and eventually made them stop doing that), but the exercises were probably helpful.
I resisted the epidural treatment for weeks, and eventually agreed to try it. For me, it was a wonder cure. It sounds like you weren't so lucky.
The big question (other than whether PT actually does anything) is whether the bulging disk actually means anything. There's some reason to believe it's meaningless. I was 50 at the time of that episode. Apparently, if you take a random collection of 50 year old men and image their spines, you'll find most of them have bulging disks, etc. While there's certainly correlation between bulging disks and back pain, it's not clear that there's really any causality. There's probably lots of 50 year old men walking around with bulging disks and no symptoms.
In any case, yes, I still have lower back pain. Not all the time, and not the kind that almost laid me out on the ground in the parking lot, but some. My general experience is that keeping moving is good. If my back is hurting, sitting and doing nothing makes it worse. Doing something like some gentle bike riding helps.
So, my (non-medical) recommendation is that if you feel you need a break from heavy lifting, still keep doing something. Ride a bike. Jump on the rowing machine. Don't go crazy, but also push yourself a little bit each day.
Google for "Stuart McGill's Big Three" (or, just go here). I do curl-ups a lot.
Read the "Conditioning" chapter in The Barbell Prescription. Even if you don't lift barbells, it's a great analysis of various exercise types. Short version: at a typical gym, stick to the bikes and rowing machines, and stay away from the treadmills. If your gym has a recumbent bike, you might find that easier on your back than an upright one.
Barbell Prescription makes a compelling argument that as we age lowering reps actually makes more sense, since we're more sensitive to repetitive use injuries.
That said, 45 isn't that old and 8 reps is certainly going to be better for hypertrophy than 5.
Personally, I follow BP's general plan (mostly 3x5's) but substitute in 10-15 rep sets for accessory exercises with smaller muscles where I care more about hypertrophy than strength (pecs, biceps, triceps) and/or body weight exercises where it's just more convenient (pullups, dips).
The Starting Strength folks put out a book (The Barbell Prescription) specifically laying out the case for why barbell training is important for older people (including 70+), and how they can go about doing it (program modifications, etc.). One of the authors (an ER doc) has a YouTube channel (GreySteel) with some interesting discussions on the effect of strength training on age-related diseases.
Both book and channel are fairly good about citing the academic literature, so there seems to be good evidence that people should work out as long as they're capable of doing so, no matter their age.
Send him a copy of The Barbell Prescription , and point him toward The Greysteel Channel on YouTube.
"...would it be beneficial for him to do 5x5? any advice is great, but please don't say that he should start barbell training..." Huh? 5x5 is barbell training. But you're right, you can't force him to do anything.
Send him a copy of [The Barbell Prescription]([https://toptalkedbooks.com/amzn/0982522770) ), and point him in the direction of the [Greysteel YouTube Channel](https://www.youtube.com/greysteel) for starters.
Send him a copy of The Barbell Prescription , and point him in the direction of the Greysteel YouTube Channel for starters.
If you are over 35 (and sedentary), I'd really recommend reading "The Barbell Prescription" https://www.amazon.com/Barbell-Prescription-Strength-Trainin... — it will be a much better guide than most advice available online, which seems to be directed at youngsters.