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The PACE Study - Experiment 1

PTH and Calcium Responses to Exercise, Experiment 1

The PACE study will examine how disruptions in blood calcium levels during exercise affect the bone response to exercise in women and men. Exercise generally has favorable benefits to bone health. However, previous research studies have reported bone density losses over the course of a year in male and female cyclists. Studies have also shown that moderate and vigorous exercise results in calcium loss in sweat. This loss was accompanied by a decrease in blood calcium and an increase in parathyroid hormone (or PTH), which causes bone to release calcium. It is possible that bone loss in people who exercise a lot is related to calcium loss during exercise. The first experiment in the PACE study will determine whether the amount of calcium lost through sweating during exercise affects the decrease in blood calcium and the release of calcium from bone.

The PACE Experiment 1 study involves two 1-hour vigorous exercise sessions on a stationary bike performed one month apart. After a pre-exercise meal containing a known amount of calories and calcium, the exercise sessions will be performed either in a warm (~80°) or a cool (~60°) room. The temperature for exercise sessions will be selected in random order. The study will be held on the University of Colorado - Anschutz Medical Campus.

The men and women who participate in this study must meet these requirements:

  • In generally good health
  • There is no cost to you for taking part in the study
  • 18 to 45 years of age
  • regularly cycle for exercise and able to ride for an hour at a vigorous intensity
  • women must have regular menstrual cycles
  • not taking medications for osteoporosis

Volunteers for the PACE study will undergo a physical exam, a bone density test, a stationary cycle exercise test, and blood tests to determine whether they are eligible for the study. These tests will be performed at no charge. Participants will be compensated for their time for the two exercise sessions.

The PACE study is supported by the Department of Defense and the National Institutes of Health.

For more information about PACE, please contact Vanessa Sherk at 303-724-6529 or

Principle investigator: Wendy M Kohrt, PhD
COMIRB#: 12-0767
Version#: v1.1, 10 July 2012