Hi there I've just started going to the gym again and have noticed that when I'm doing cardio my heart rate gets really really high (about 198) and the machine tells me I'm off the chart!! I've heard various things about heart rate and how you should be at about 70-80% of your max, so what is true and best for fat loss without sacrificing muscle? Should I lower the intensity of my workouts? I find this difficult to get my head around because I was always under the impression that I have to work to the highest intensity that I can to get the best results. Also, I'm training to do a 5k run (not much to most but I am rather unfit!), this run is in about 6 weeks so I need to keep up with the intensity to be able to get there!

Would just like some opinions about what is best

Thanks

Fact is, the higher your heart rate the more calories you burn. If you are comfortable at the rate you are hitting then I wouldn't worry about it. Mine regularly got that high, up to 210 one one occasion, when I first started exercising. Now it peaks around 188-192 at my hardest points in HIIT. Your cardiovascular system will strengthen over time. I say keep it up.

Google 'myth of the fat-burning zone' if you want to read more about the different theories on heart rate levels and fat burning levels and such. There are a lot of posts on here about it, too, actually. I have one from a couple of years ago that you might be able to find if you search my user ID as well.
Good luck on your 5K!

VARIETY is best.

Some days go easier but longer, some days go harder and shorter. Work out the entire RANGE of your cardiovascular system and you will get the best results.

that is fantastic advice ennay