weight training, page-42

Adjustable weights, where you can screw weights on and off are the best. Not all muscle groups will strengthen equally, there is different forces placed on arms/legs with different angle movements and muscle groups, such as pec and delt are prime movers and should increase alot more than the rotator cuff for instance.

Generally with weight training, its the routine of consistency coupled with a 'good' diet and 'good' training regine and you should be right. As with stock trading, if your method works, dont try to emulate someone elses because they get a 1% better return. Having the right principles correct is most important but the nitty gritty detial of exact time of eating, exact amount of protein etc. is contentious, unstudied and simply just guessing as to what is right.

Most important for you, is that you progressively overload the workouts appropriately, realistically, if you are still on 5kg weights you should be able to up the weight by A 1-2 kg OR B 1-2 reps per set (op A for more bulk, B for endurance) every 2-3 weeks. I would not progress more than 1-2kg at a time and then you progressively overload again just as it starts feeling a little bit easier, you'll find that it takes longer and longer as you get into the higher weights to be to progress the weight.

Most importantly for you, in terms of fitness, is injury prevention. You sound motivated, diet good enough, exercise good enough, your only worry is an injury that stops you for months. Make sure you stretch, after the session is a good time but also on your off days as you are doing this to make sure prime mover muscle groups dont tighten up and put press on joints. The other thing I would recommend, is that you make sure you research the rotator cuff, its involvement in dynamic stability of the shoulder and how to maximise its stabilising affect around the shoulder. Most people I see at work who have injuries due to doing weights generally will have tight pec major and minor, kyphotic (forward curving) thoracic spine and weakness/spasm through the rotator cuff muscles.

Oh btw, I'm a physiotherapist, been working in the industry now for 5 years. Hopefully some of this info helps, a big wall of text I know but when I wind up I just keep typing when talking about issues to do with work lol.