speed intervals

I did a speed interval on Thursday, 5th November. I located a dirt track a little away from my house which had a 200 metre track with a 100 metre loop jutting out on one side, which made it a 300 metres loop for me, I did a warm up of about 5 rounds and then 4 into 800 metres (2 loops of 300 metres and one loop of 200m) interspersed with easy jog for 200 metres in between and followed it up with a 800 metres easy jog to finish it. I got quite ragged in the end, when i was sprinting away in the last section. being a first experience for me, i think i did okay. Track measurement may not have been exactly accurate, but the interval work out was achieved.  Yes, i did some stretching after the initial easy run and in the end.