Part 4 of the 25 minute HIIT for runners series. Each session consists of 5 blocks. Each block is 25 seconds of work, followed by 10 seconds of rest, repeated for a total of 8 times. The intensity increases

I ran 21km after work today. The full marathon is coming near, so I intended to run at slowish pace in order not to get tired. But it looked like rain any time then, so I ended up running at faster pace