What speed are you doing on the treadmill? I'm 18stone and limit myself to 5mph. This enables me to add a bit of float and bounce to my form at the 3 to 4 minute mark once warmed up and relaxed.What I do notice when I run is that it feels like my feet smash into the ground with tremendous force, as if I was massively overweight. I seem to lack the spring and float that runners often appear to have, as if gravity is only just keeping them on the ground. Maybe being 6'4" and 16 stone doesn't help?
Looking at Strava my body says 'no way' at the 8.5km point (that's a weekly total). By that I mean I get some sort of minor twist or strain. Over the last 5 months I've had:
Grumbling left Achilles - left it a week over Christmas. All good.
Creaking, clicking right hip - old injury coming back. I kept at it and stretched out properly. The muscles are now strong enough to support the joint.
Twisted left knee - my fault, tried 3 x 5mins while really tired. Kept going as felt fine after recovery 2 min walks. BUT lost running form at 10 ~ 15min mark and was flailing a bit.
Modern Humans are the very definition of runners. If you walk you barely use your gluts. You only really use them when jogging/running. It's a big muscle set to not be using most of the time. It's just how we've evolved.I'm just not a runner and never have been...
Have a watch of Dr. Alice Roberts 3 part programme on our evolution.