Would not running for 2 days effect me in my meet?

without going into further detail on why I would be missing 2 days (although it is an injury)...... I just want to plain out know if missing 2 days of running will effect my 400 time in my meet monday. I did a hard 300 workout on thursday and went in the pool for a mini aquatic workout. Also if it will effect my time..... what else besides riding a bike/swimming can I do to keep my endurance up WITHOUT running on my legs...... weight training?