LifeFitness Treadmill (Walking speed 3.8 MPH, Running Speed 7.0 MPH): 5 min warmup, 2 intervals of 4 minutes running/2 minutes walking. I am supposed to now have 20 minutes of total running time and I thought that 5 intervals of 4 minutes running/2 minutes walking would ease me in, even though I would only rest 2 minutes. Just as well: After the week where I'm doing 7-minute runs, there will be no rest periods greater than 2 minutes.
First Interval: Heart rate began at 145, ended at 172.
Second interval: Heart rate began at 150, ended at 182. Started getting a stitch at around the 3 minute mark but ran through it.
I walked until I could get my heart rate to about 148, then I tried a third interval. In two minutes, I was up to a BPM of 188 and just could not continue, so I walked the rest. Maybe, I'm still recovering from what ailed me, but I really see this as having to condition my heart to recover faster and be more efficient. So I'll gradually keep adding to this until I can get my twenty minutes in good shape, then I will start my week with 5 minutes running, 2.5 minutes walking.