Heart rate goes so high in hot shower. about 150-160 bpm. im 17 and athlete?

Tachycardia: Exposure to heat dilates the blood vessels and lowers the blood pressure enough to cause a rise in the heart rate, but 150-170 would be abnormally rapid. If you are accurate in determining your heart rate and especially if you note marked tachycardia under other circumstances, I recommend that you consult a cardiologist for evaluation and be checked for overactive thyroid as well.