Today I went to the track and did my heart rate workout for 30 minutes at a higher level of intensity - my average heart rate was 145 bpm.

Then I ran 5 x 300 meters. Times were:

1:00, 1:00, 0:59, 0:58, 0:57

I am modelling my training after Roger Bannister, the British miler who broke the 4 minute mile barrier in 1954. He trained 30 minutes a day on his lunch break while he was in medical school. He ran on a nearby track and did mostly all fast short interval running every day.

Most of my workout is below my aerobic threshold heart rate (about 156 bpm). Only the 1500 to 1600 meters of repeats are above my threshold. When I finished my last 300 today, my heart rate was 159 bpm. All five 300s took a total of 11:00 with an average heart rate of 146 bpm. I allowed my heart rate to drop to 120 bpm after each 300 meter repeat.