Lifting weights this winter for first time ever. Been biking 2 years. I try to circut train. Doing twenty reps of each excercise. Leg extension, lat pull down, step up, pushups, seated row, leg lift, standing row and, adobminal with twist on ball. AKA the Joe Friel mountain bike bible regime. This takes about an hour to do three times. My question is. How come I feel like puking by the end of second go round? I don't but I have come close. I usually walk on the track to recover if I feel bad. What is my body doing when I feel this way? Have I used all my muscle glycogen? I always eat something before lifting so its not hunger. My HR is usually in the 150s while lifting. With spikes into 180s while doing excercises. Max is 200. Usually do a 1 hour endurance ride after and feel better after 10 minutes or so. Thanks in advance.