No Pain No Gain: This is so harmful for anyone. You can comfortably gain muscle without being sore. Our president has done it this whole year. Pain is your body telling you something is wrong. When thinking about this population, they could or not feel pain and tension like everyone else and can get really injured if told you're not working unless you are hurting.
Sit-ups are mandatory for 6 pack abs: Sit-ups can cause neck and lower back pain and issues down the road. There are numerous exercises that can be utilized to promote core strength gains. When it comes to the ASD population, if they are hyper sensitive to pain, the second they feel pain in one of those areas, it could be plausible they hang the hat up on fitness for good. Also you have to lose fat to get a six pack, otherwise you just have fat over muscle which will stick out more.
Girls get bulky with weight training: Unless a girl takes a bunch of protein and other supplements, there is very little chance a girl will get overly bulky. If a girl in this population wants to lift, let her. It wont hinder anything if she enjoys it.
Variety is key: This is absolutely and totally wrong. The body needs to witness a stimulus and certain amount of times to adapt to it. You should only be switching up a workout if you're hitting a plateau. Our body's do not like change, just like this populations mind. Keep the variation to a minimum and only when necessary.
Cardio equals weight loss: Without getting overly scientific, cardio can help reduce weight but not fat since you would have to run a marathon type distance to start to lose fat during exercise. The best way to lose fat is to gain muscle through weight training and supplement that program with cardio of a preferred nature. Also you have to eat better.