What to start with? (and my mistakes)

[Tooth&Claw]

Hi guys, asking for some advice..

I'm 39, 72kg/178cm, been a skinny type all of my life, narrow bones, VERY hard to gain any muscle. Tried few times... 2 weeks of training.. no result - dropped it. Some other time later, 1 month of training - no result - stopped. Got used to live with it.

Seriously, now I want to give it a try again. Got my blood test results recently.

Testosterone - 4.06 (range: 2.80 - 8.00)
Cortisol - 20.09 (range: 6.2 - 19.4)
Thyroxine T4 - 5.89 (range: 5.1 - 14.10)
Estradiol - 11.5 (range: 7.63 - 42.6)

Thats all I can get in local hospital (they dont do SHBG and others). So I assume my T is low and cortisol is above normal?

Half a year ago I got a lumbar disc injury (it's actually a DDD) so I cant put any stress on my back.
Spent 2 months mostly in bed, recovering.

So I decided to improve my stamina and endurance before doing any workouts.
Started to walk up the hills (15km three times a week, up and down) or on a treadmill with incline.

Very satisfied with the results, can run up a long staircase without any problems, normal pulse while resting is 60 bpm (before it was 80-85).

Ironically, I was sure that aerobics will help burn some fat but it didn't. No matter what I eat.
And I eat mostly oats, egg whtes, tuna, sometimes a whole chicken without skin, fruits, rice.
No french fries, no salami, no ice cream, no sugar.

So, I think it's time to move on. Enough with aerobics and let's get to a serious stuff.

But the more I read, the more I get confused - how to kickstart the anabolism? I've been told that I need
to train big muscles, like legs, and the rest will follow. The trouble is I can't do sit-ups or put any load on my back.

I'd highly welcome any advice from somebody of my age and similar genetics. (If you're 25 and have your T through the roof and arms like treetrunks naturally - that's ok, but we are too different).

Thanks guys!

[HellbentSOB]

(If you're 25 and have your T through the roof and arms like treetrunks naturally - that's ok, but we are too different).

Those guys you reference aren't different species or anything and most likely have a huge amount of information that could help you.
That being said, you're focused on the wrong things.
You're focused on blood-work and stamina instead of body fat and nutrition.

I have lower lumbar degeneration and I can relate to the struggles of training with such a disability.
I would focus on your nutrition starting from BMR to protein/fat/carb ratios and eat the correct amounts since nothing here about your nutrition is that specific.