What is the maximum heart rate that a fit badminton player can safely sustain when playing? Some say it is 220-your age x 85%. Others say it is 220-your age x 90% to 100%. At the 220-your age x 100% zone, some say you can overstrain your heart. I am not too sure and am a bit confused. According to such guidelines, 100% of my maximum heart rate (220-65), is 155 beats per minute. I wear a pulse monitor, and I do not have trouble getting oxygen into my muscles at 155. Sometimes I do hit 185, and I do get tired at this rate, in which case I use delaying tatics to enable my beat to go down to 160+. Are the guidelines right, in which case I should be dead, or are they just guidelines? I need some reassurances and some advice, as I could be putting myself at risk.