Should vigorous exercise be avoided the day before saliva collection for cortisol (adrenal function)?
Collection should be done on a day when you are engaging in your normal, routine activity. Any exercise will affect cortisol levels. Therefore, if you routinely engage in strenuous exercise and you want to see what happens to your cortisol with your exercise, then testing on that day is fine. However, if you do not routinely exercise or do not want to see the effect of exercise on your cortisol levels, refrain from vigorous exercise (e.g., running, biking, etc.) on the day of testing.