Still recovering

The weather has turned cold and rainy, so I headed to an overly crowded gym after work. I hopped on the treadmill for a 4 mile run. I eased into it, but quickly switch to 1/4 mile repeats, alternating between an 8.5-9.5 mph pace on the high end and 6 mph on the low end. I struggled with the my breath. My legs seem fine, but I can tell that my internal systems are not recovered. I'll take it easy tomorrow.