I'm sure when he's doing legs, it's going to hurt his lower back.
How can you tell if you 'OVER TRAIN'....i mean.....I dunno....never mind
in all seriousness........I was doing some reading myself about lower back pain AND........They say.....believe it or not......that sex can help....NO JOKE....reason....if you're going through therapy...it takes a lot of effort to get through your session because of the pain HOWEVER....study shows sex will help because you're more than likely going to work through the pain because of the "end" result you get when you're "done." I swear...I'm not kidding.
I'm a Light Infantry Soldier who for a living carries heavy loads on my back (120 pound ruck sack, 40 pound machine gun) I am 28 and have been a soldier for seven years. When I say over- train I mean run up to 16 KM in the mourning, swim for an hour at lunch, wieghtlift an hour after lunch and box for two hours a day. I train like this for 5 days a week and weekends off.(Unless I'm in the field or on tour). My back pain seemed to come from nowhere and feels tight all the time. Are weaker abs a reason??. If someone has insight it would be great.
You are sure doin' a lot of cardio in a day! I know you are only 28, but...the lower back pain could just be a signal that you are either doing too much or wearing that part down a little. You might try out a good massage, or maybe a chiropractor if it persists. There should be some good stretching exercises out there that might help strengthen the back.
As good as that swimming is at soothing your muscles, I can't imagine all that running AND that boxing not winding your whole body up tighter than a clock -