When i exercise, my heart rate goes between 160-175bpm. is this too high for a 37 year old woman? target heart rate calc says 146 maximum.

Depends: A formula widely accepted is 220-age=maximum heart rate. Keep in mind though that this is a simplistic formula with age as the only variable and standard deviation for this equation is 10 to 15 bpm. Target heart rates for aggressive cardioconditioning are generally recommended at 80% of your calculated maximum for a healthy individual. See your first GP to discuss any possible contraindications