Your max heart rate as per formula is 157. I'm guessing that to hit that you are going flat out. My question is, why would you want to.
According to the formula, mine is 170. I did a test and the max i could hit was 168, but i was at the absolute maximum effort for a few seconds, totally gasping for air. In hindsight i'm not sure it was a good idea. When i run it's anywhere between 140 and the low 150's. If i head towards 160, i slow down a bit.
In short, i'm saying keep an eye on your heart rate, but listen to your body. You know what an easy run is, and what a hard run is. There's no need to go near your MHR, and i also think its not a good idea.
Andrew Marr, the BBC bloke recently had a stroke. He was trying that fad which was based around short bursts of very high intensity workouts.
Hi Kev. I'm the same age as you and started running a few years ago. I think the most important thing is listen to your body. If you get any minor niggles, lay off for a few days, maybe a week or so. Don't push it.
I do running and cycling. If i get a niggle running, i stop and cycle for a few weeks. I also try to mix it up so never run more than 3 times a week.
Laura, how old are you. My attitude is just go for it. I started running 2 years ago and my first run was 30 minutes, full pelt, none of this walking malarky. The only advice i would give you is get a heart rate monitor. That way you can see if you are overdoing it, and you can also measure improvements. Not only by time, but by heart rate.
Try this fitness test based on heart rate recovery. If you do well its a good motivator to carry on. Basically you exercise to a given heart rate target, then see how quickly it drops over 2 mins. The lower it drops, the fitter you are.