The reverse of this question is very common: "how does my physical job impact recovery?" and the answer generally comes back to be some, but not as much as you think. As long as you are already adapted to the job and the demands don't change, you should recover fine, just make sure your calories and sleep are adequate to the total stress of job plus training.
I imagine that sitting all day is similar. If you are already adapted to that particular flavor of stress, it's probably not negatively impacting your training. The exception would be if you are sitting in a way that is creating or aggravating an injury.