How long before HIIT benefits kick in?

Martin King 8

Hi all,

Does anyone have experience of doing High Intenstity Interval Training, or similar? 

I was wondering, would doing something like this once or twice a week (as part of a plan that has me running 5 days out of 7, including 1 LSR and the rest easy) make much difference to my fitness in 1 month?

I'm doing Reading Half in mid March, my best traing pace in runs over 10 miles is 7.25m/min but I'd need to shave 30secs off that to get a sub90 min time.  Is that possible, or have I left too much to improve before then?