Originally Posted by
svtmike
A cardiac stress test is the only way I know of to find out if that heart rate is 'safe' for you.
+1 That's why I tell people exercising that the formula of 220 minus your age, times .6 and .8 will give you a very conservative guesstiment at best of what your cardio target workout range should be. This is because the starting number of 220 minus your age is not your actual max heart rate and this standard formula is usually on the low side.