Raise a child from birth in high-gravity, low-oxygen environment so he is naturally stronger and more athletic than normal people & create a super soldier

I vaguely remember an experiment somebody did about chickens in a high-gravity environment and they had significantly denser/stronger muscles than normal chickens. The memory just popped into my head during a workout because I was thinking about muscles while Eminem's "My First Single" was talking about fucking chickens and it clicked.

I have done zero research but I assume there will be zero risks or drawbacks! I'll take my government research grant now, Mr. President!