With the “220 minus your age” rule my max would be 182 bpm. If I run at 175 bpm I can manage 30 minutes and run ~6K in that time (and be very tired the rest of

With the “220 minus your age” rule my max would be 182 bpm. If I run at 175 bpm I can manage 30 minutes and run ~6K in that time (and be very tired the rest of the day). 165 bpm I can manage for an hour. Beyond that, boredom and sore feet set in before cardio becomes the limit. I can’t imagine ever running 25K…even at a low(er) HR. Maybe if I lose another 5 to 10 kg of weight…