Hi :) i hope your son is doing well and his healing sounds fantastic :)
Its not other parents that you should be asking i believe it should be open heart surgery patients as allthough each person is individual it is fair to say that the recovery goes in stages and i now help people in my area who are in their 20's and going threw heart surgery so your question is one of the most common.
Your son is 7 years old and allthough you would say he doesnt know what went on he does and he alo has to adjust to tht as well as you as parents. Its very very difficult for any individual to adjust to i certainly found it hard when i was 21 having it done and he is human and will also find it hard.
16 weeks is still very early days and allthough the doctors will give you the all clear live your life as normal i think from experience of talking to others and being in a rehab facility with cardiac rehab and also helping others who are young its very easy for these drs and surgeons to tell us this as this 12 week lifting restriction is removed and you are free to go but you also have to remember its mentally and psychology exhausting for the person having ohs. Not only that but his body has taken a serious beating one million rounds with mike tyson and it isnt 16 weeks that its gonna take for that to recover.
Talking of his body he is still growing at 7 years old and so for us older people to comment and i am only in my 20s it was super hard for my body to readjust and re align and still 15 months on i see a chiropractor and for him at 7 years old his bones his ribs his heart have all been moved and handled proded touched and will hurt and be very tender id say for at least a year and he is still growing i had stopped growing!. I and many people have twinges niggles pains, i still do now and i am 15months post op.
So being 21 when i had my heart surgery i cant comment on a 7 year olds fitness but i can give you my recovery rate with fitness. AGES! i ran a 10k last week and it took me a while to train i felt like a baby starting new and i was fit before my op. I went into a rehab facility after 8 weeks and started doing light exercise and i was 21 so for a 7 year old to get up and play badminton and go cycling i think is asking a lot. By normal activities he/she is probably referring to light activities like a bit of gardening etc to get everything moving again as allthough the op was 16 weeks ago he lay in bed and wasnt moving or lifting for that time so all strength goes. To give you some idea of how fitness went for someone who is older than him...
rehab for 6 weeks from 8 weeks then phase 2 rehab for 16 weeks so that took till 4 and a bit months so thats building up i then went on to a gym to work alongside someone who was able to monitor my fitness and i was only able to walk on the treadmill for 5 minutes at first without getting out of breath but i built it up fo rmonths and months and months ane by the end of that time which was 9 months post op i coud walk on the treadmill on a steep incline for an hour but it took me 9 months and 4 days a week at the gym to get to that. Not only that but its the fear of everything that he may not express that also holds us back and gets us worrying. Id say it takes a good year to fully recover and thats not fully fully as now i run 5 miles twice a week and do yoga and i still feel it more than anyone i exercise with so its a long healing process and you need to give him time especially at his age as his body needs extra time to realign and re adjust and also his energy fields will not be in balance as major trauma surgery effects us not just in our physical body.
breathlessness and sitting down after badminton or cycling is what normal people would do and someone who had ohs 16 weeks ago will definetly do i think i would do it now and i am super duper fit. Id maybe suggest getting in contact with a local rehab centre and asking it they could suggest light gently exercises. I walked heaps and heaps and that helped me so much and i did that fo rmonths and months and even then i would have to stop. If i do anything extra now and i know that a lot of people alos sympathise with this i feel it for days afterwards. Cycling and badminton are quite intense exercises to start off with and i cant say they are average as it takes a long time to get to cycling stage for a normal person let alone a young boy gone threw heart surgery.
The surgeons and drs are fantastic cant fault them but with recovery its such a slow process and its very hard to tell someone its going to take a good year but it honestly will.
Try not to google anything as i made that mistake and im sure others will hold their hands up to it and google doesnt hold the answer to it 99% of the time.
He is doing so so well by the sounds of it and he needs time to adjust and his body needs time to absorb and get used to not only that he had heart surgery and was proded and poked but that he now has a beautiful fully working heart and his organs are having a party that they get the right blood and enough oxygen.
Sending him love and healing energy.