Reason for increase in HR whilst running at a slower pace following bike accident?

[Chris_tri]

3 weeks away from undertaking my first ironman I crashed into a barrier at between 25-30 mph whilst out on a training ride. I was unconscious for a couple of minutes and taken to hospital on a spinal board. My injuries were; broken collar bone, 8 broken ribs (left side), 2 broken vertebrae and a collapsed lung (left side).

It's been 9 weeks since my accident and my shoulder and ribs are about 90% repaired and had no issues with my back. I've had a few 30 minute sessions on my bike on my indoor trainer and swam twice. I've been out running 4 times but my heart rate is concerning me. On my first run, I could only run at 10 min/mile due to my physical condition but that has improved. However, I'm now unable to run quicker than 9min30sec min/mile as my HR rises close to my max. This hasn't improved over my runs.

Prior to my injury in may I could run sub 1hr30 half marathon which is less than 7min/mile but now my HR is the same for 9min30 /mile. I'm very nervous about trying to increase my pace not knowing why my HR has been effected so much by my accident. I'm unsure if this due to my collapsed lung having not healed or whether there is an underlying heart issue.

My questions are:
1. Has anyone experienced the same?
2. Does anyone have any ideas on the reason why my pace vs HR has been effected so much?
3. Am I best to rest or push myself (will training accelerate healing)?
Thanks
Chris

[gymdandee]

I suggest seeing your Cardiologist and get the OK from him/her.

[Chris_tri]

just had all clear from cardiologist thanks so going for a lung function test next.