Declines in serum calcium during exercise may cause increases in markers of bone resorption. This study will determine if preventing the decline serum ionized calcium experienced at the onset of exercise through the use of a "calcium clamp" also prevents increases in blood biomarkers associated with bone resorption.
Participants will undergo two identical walking exercise sessions on a treadmill. One session will occur until continuous calcium infusion and the other will be under continuous saline infusion. C-telopeptide, parathyroid hormone, total calcium, and serum ionized calcium will be monitored to distinguish differences in bone activity under the two conditions.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
12
Calcium (as either calcium chloride or calcium gluconate in half normal saline) will be delivered via IV during exercise to keep serum ionized calcium levels above baseline. The clamp is modeled after the hyperglycemic glucose clamp.
This is the placebo comparative infusion. Half-normal saline will be infused at the second collection visit following the identical infusion schedule determined during the calcium infusion visit.
University of Colorado Hospital
Aurora, Colorado, United States
Change in Parathyroid Hormone (PTH)
Change in PTH will be measured from baseline to end of exercise
Time frame: baseline, 60 minutes
Change in C-telopeptide (CTX)
Change in CTX will be measured from baseline to the end of 60 minutes of exercise
Time frame: baseline, 60 minutes
Change in Ionized Calcium
Change in ionized calcium will be measured from baseline to the end of 60 minutes of exercise
Time frame: baseline, 60 minutes
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