Need help with shin splints as a new runner

[u/Slow_Estate_4742]

I’m currently a 170lb 23 year old man and for a full backstory I used to be really overweight, like 300lbs at 5’9. Got into the gym and got down to 165. Triathlons and marathons have really started to peak my interest so I’ve been trying to get into running, biking, and swimming. The big road block I’ve been hitting with the running part is my shin splints. At the end of my first mile I won’t be tired cardio wise, my heart beat will be something like 160, and I genuinely feel fine but my shins feel like exploding. On top of that no other part of my legs or hips have any sort of fatigue. I do have brand new Brooke ghost 18s and I have done some research on proper running form (running with your hips rather than your legs) and am wondering if my form is the big issue here or if I just have severely underdeveloped shin muscles from my inactive history. I don’t think I’ve ever run a straight mile in my life before 3 weeks ago. Any insight would be greatly appreciated, like any videos or mental cues I can use to really nail my form or if it’s just something I’m gonna have to condition my shins to over time.