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The PACE Research Study

PTH and Calcium Responses to Exercise, Experiment 2

The PACE research study will examine how disruptions in blood calcium levels during exercise affect the bone response to exercise. Exercise generally has favorable benefits to bone health. However, previous research studies have reported significant 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. PACE Experiment 2 will determine whether preventing calcium loss during exercise prevents increases in PTH.

The PACE Experiment 2 research study involves two 1-hour vigorous exercise sessions on a stationary bike. Blood calcium levels will be monitored during and for 4 hours after exercise. During the first ride, a calcium solution will be administered through a vein to prevent a decline in calcium. During the second ride, the same volume of saline will be administered through a vein. A pre-exercise meal containing a specific amount of calories and calcium will be provided. We will collect urine samples before and after each ride to measure calcium loss. The research study will be held on the University of Colorado - Anschutz Medical Campus.

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

  • in generally good health
  • 18 to 45 years of age
  • regularly cycle for exercise and able to ride for an hour at a vigorous intensity
  • not taking medications for osteoporosis
  • no history of asthma

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 exercise session.

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#: v2.1, 28 February 2014