NOTE: Things got changed to "civilise" this discussion.
Oxidane, I can't see your pics, but what you need to bear in mind, is visual changes are only likely after 4-6 weeks, as most people need time to adapt to weightbearing exercises, so expecting to see much change after 8 weeks is difficult.
The difference in pictures could be slight, or the way the second one was taken, I.E. angle, light conditions etc etc, as I say the links don't work for me.
Perhaps such things were influencing Houstans comments.
Your trainer guy is WRONG. Forums are a superb resource, and if it wasn't for places like this, many people would get nowhere, or have to pay other people money, they might possibly not be able to afford to get results, because not everyone can afford to buy healthy food, then pay a guy to tell them how to eat it properly.
You are 13. You cannot expect your body to tolerate weights too easily, and if your diet isn't right, to allow you to keep properly developing things like bones as well as muscles, you could be stressing your bones doing weights, and causing possible issues, if your bones are being given weight related stresses, that negatively affect their development.
This is not us treating you like a 5 year old, this is us saying we think you lifting weights, might be causing yourself slight problems, that could get worse over time.
Do you really want physical problems when you're 21?
I've seen kids in Gym, around your age, 13, 14, 15, pissing about on stuff, leaning Back on Cable Rows, leaning too far forward on a crappy Bicep Machine, Bench Pressing Medicine Balls at 3 reps per second, and they know nothing, use half technique, and think for some reason, using a Tricep Machine, then a Pec Deck, then a Cable Row is a good structure of workout, because those machines are all next to each other.
I recently saw a kid who looked about 12, trying to add weight to a bar, and he was too weak to get a clip off, and gave up.
Now I'm not saying you're weak, a stupid kid, or doing things wrong, but if you get injured, or get any long-term issues with weights, affecting muscles and bones, e.g. back pain, stiff joints etc etc, you could be seriously looking at adult life, where you feel pain and have to take meds to get rid of it, or have to have surgery to correct issues, that may 20-30 years later, come back with more aging.
You don't need to do weights at your age. You "could", do bodyweighted stuff for now, you know like Press-ups, Planks, Body Squats, etc etc, and just eat well, as well as doing some Cardio, to keep your body good, like your Sprints for example.
You've got a lot of Testosterone and GH potential, that you can use to give you good teenage growth, then when your Bones and muscles are stronger at 15, go onto weights, when your body can handle it better.
If you lift serious or semi-serious weight levels, you risk injury, and physical problems when you're older, and if you stay with very light weights like 2-4lb stuff, you might as well not do it at all, the benefit you'd get from bodyweight stuff, would be better than using pee wee weights, in that instance.
It's not about us trying to make you feel like a dumb kid, or us telling you you're not good enough to run with the pack bud, it's about us keeping you safe.
If you got an injury, or some pain from lifting weights, and came on here telling us, how do you think we're going to feel, or you for that matter?
If your trainer guy was being more savvy, he'd realise you might be at risk doing weights, even if he said, don't go full on, don't do failure stuff, don't lift for 6-8 rep maxes, go for 20 rep weight levels, and stop at 8-10 reps per set, just to stop you going too hard and heavy, as that might still be a risk.
It's easy to say no way I'm not going to stop lifting, and butt your head against a verbal wall, but you might do something that stops you altogether, no choice, you get screwed, and you're looking at surgery, pain meds, and some stuff you like doing you couldn't do anymore, and your mates could, which would be pretty pissy.
Do you hear what I'm saying bro?
We don't say no to stuff to sound like grumpy old men, we say it because it makes sense. We CAN help you, and so can forums like this, but you have to let us, otherwise carry on as you are, and possibly get a problem, but we can't and won't, (if that happens), take flack of your family because you got hurt, when we said bud don't do weights at 13, you might get hurt.
You just need to think about what you're doing, and what might happen if it goes wrong.
I suggest you do bodyweight stuff for now, keep on the sprints, and eat well. Let your muscles and bones develop from body stuff, good food and then in 18-24 months, get on the weights, when your body can take it better.
Develop your body in like that, and then any issues could get, will be much, much less likely to happen.
I can see you're a good kid, and you want to do this, and you should be proud of yourself yeah

as most people your age don't care about their bodies, don't think about it, and end up doing stuff that's crappy and bad for them when they're 15+, sometimes younger.
So think about it alright, and tell us what you feel. If you want us to help, then let us do it "our" way, if you don't fine, but we can't help you avoid issues, if you carry on like you're doing, and get one.
Be smart okay

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