Tell the trainer you want your money back. Most trainers don't actually train for results because they would rather be safe and not push their clients hard to keep them coming back than push their clients hard and make them quit.
He isn't pushing you hard enough or you aren't making him push you hard enough. Until one of those happens your results aren't going to change. And if I'm being honest, for 6 months in those results are terrible. No muscle definition at all.
Getting in great shape is hard work. It causes pain. Are you willing to feel like you have been run over by a truck 6 days a week? To hurt so bad that you can barely bend down to pick up something you dropped on the floor because you are so sore?
This is what keeps people from being in shape...they aren't willing to pay the price.
I second this. It has to hurt to sit down, stand, move, etc. However, I wouldn't say to do this all the time though marmel because that could burn out his CNS. Plus, maybe he was much worse off 6 months ago, we don't have a before pic.
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I'd have to say to do full body workouts that cause you to SWEAT a crapton rather than weight-training specifically. Building muscle isn't what you need right now, I'd say it's losing fat. So more full body workouts, most likely calisthenics since it would be the least strain on on your joints at your age, maybe a little bit of plyometrics, and then some *GASP* cardio too. That's just gonna be to add the most basic stress on your body. If you are only exercising 3 or 4 times a week, then I'd say to up the intensity every week for about 6 weeks ± 2 weeks. Then switch it to upper and lower body with the same intensity for another 8-10 weeks with deloads/rest/stretch days taken as necessary. You've built the basis for better than average fitness at this point and I'd tell you to only do some kind of cardio that's easier on the joints, such as swimming for example. Cycling is fine, but it doesn't cause an increase in sexual performance for whatever reason no matter how fit you get doing it. Do this for about a week or two after and then get back into the upper/lower split that you've been doing for another 3 weeks ± 1 week. Then get into some real hardcore weightlifting. I personally like the legs/push/pull split the best, as I train for strength and compound exercises promote strength more so than isolation (compound meaning activating more than one muscle at a time e.g. bench press, pull-ups, squats; isolation meaning only one muscle at a time e.g. curls, leg extensions, tricep extensions). After this just keep lifting with whatever split your trainer tells you to do and then just come back when it's been 6 months again. If you actually work hard with something like this, you'll see very noticeable results.
If you have been working out more than 4 times a week, then I'd tell your trainer to up the intensity a LOT because you should have at least some muscle definition by now after 6 months of training. Only if you've been working out for more than 4 days a week though.