Could I Have Ruined my Facelift From Neck Strain While Off-Roading? (photo)

I doubt that you have harmed your facelift results permanently from your activity. In fact, our facelift patients have  routinely returned to their activities after 4 weeks. Fluctuating swelling though is normal and may be temporarily worse with exercise.

The result may look much better at 9 days after the surgery - especially if a "mini-lift" has been performed. if your neck and jawline continue to worsen over the next 3 months than it is most likely due to the conservatism of the lift itself.

Looking at your photos, it appears that you also underwent skin resurfacing of face and neck which can add to swelling associated with exercise, sweating etc.

Stay in close contact to your facelift surgeon.

You're probably going to be just fine.  Edema (swelling) will persist after the facelift for months, and will fluctuate depending on your activity level, position, application of compression garments, and perhaps salt and fluid intake, medications you are using, etc.  The general trend of this swelling is to slowly resolve.  Check with your plastic surgeon though if he/she wants to see you to check it out, or, if you're anxious about it, perhaps best to go in for check up.