PTH And Calcium Responses to Exercise in Older Adults Experiment 2 (PACE Sr. 2)

Not Applicable

Completed

• Conditions: Osteoporosis
• Interventions: Drug: Calcium Chloride/Calcium Gluconate; Drug: Half-Normal Saline

• Registration Number: NCT02580604
• Lead Sponsor: University of Colorado, Denver

Brief Summary

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.

Detailed Description

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 Timeline

• Study First Submitted: 2015-10-16
• Study First Submitted QC: 2015-10-16
• Study First Posted: 2015-10-20
• Study Start: 2015-11-01
• Primary Completion: 2024-07-31
• Results First Submitted: 2025-03-24
• Study Completion: 2025-07-31
• Status Verified: 2025-08
• Results First Submitted QC: 2025-08-11
• Last Update Submitted: 2025-08-11
• Results First Posted: 2025-08-13
• Last Update Posted: 2025-08-13

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 12

Inclusion Criteria

• Healthy adults aged 60-80 y
• Currently taking a bisphosphonate medication

Exclusion Criteria

• Use of medications (other than bisphosphonates) in the past 6 months known to affect bone metabolism (e.g., thiazide diuretics, oral glucocorticoids)
• Bone Mineral Density (BMD) t score < -3.0 at the total hip or lumbar spine
• Known disease or condition associated with intestinal malabsorption
• Moderate or severe renal impairment defined as an estimated glomerular filtration rate of <60 mL/min/1.73m2 based on the Modified Diet in Renal Disease (MDRD) equation
• Chronic hepatobiliary disease, defined as liver function tests (AST, ALT) >1.5 times the upper limit of normal; if such values are obtained on initial screening and thought to be transient in nature, repeated testing will be allowed
• Thyroid dysfunction, defined as an ultrasensitive TSH <0.5 or >5.0 mU/L; volunteers with abnormal TSH values will be re-considered for participation in the study after follow-up evaluation by the PCP with initiation or adjustment of thyroid hormone replacement
• Serum calcium <8.5 or >10.3 mg/dL Serum 25(OH)D <20 ng/mL; volunteers with abnormal serum 25(OH)D values may be re-considered for participation in the study if serum 25(OH)D is >20 ng/mL after vitamin D supplementation
• Uncontrolled hypertension defined as resting systolic BP >150 mmHg or diastolic BP>90 mmHg; participants who do not meet these criteria at first screening will be re-evaluated, including after follow-up evaluation by the PCP with initiation or adjustment of anti-hypertensive medications
• History of type 1 or type 2 diabetes
• Cardiovascular disease; subjective or objective indicators of ischemic heart disease (e.g., angina, ST segment depression) or serious arrhythmias at rest or during the graded exercise test (GXT) without follow-up evaluation will be cause for exclusion; follow-up evaluation must include diagnostic testing (e.g., stress echocardiogram or thallium stress test) with interpretation by a cardiologist
• Diagnosis or history of asthma

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Calcium Infusion followed by Saline Infusion	Calcium Chloride/Calcium Gluconate	All participants will have a continuous calcium infusion during exercise at their first collection visit. The second collection visit will always be a volume-matched half-normal saline infusion.
Calcium Infusion followed by Saline Infusion	Half-Normal Saline	All participants will have a continuous calcium infusion during exercise at their first collection visit. The second collection visit will always be a volume-matched half-normal saline infusion.

Primary Outcome Measures

Name	Time	Method
Change in Parathyroid Hormone (PTH)	baseline, 60 minutes	Change in PTH will be measured from baseline to end of exercise

Secondary Outcome Measures

Name	Time	Method
Change in C-telopeptide (CTX)	baseline, 60 minutes	Change in CTX will be measured from baseline to the end of 60 minutes of exercise
Change in Ionized Calcium	baseline, 60 minutes	Change in ionized calcium will be measured from baseline to the end of 60 minutes of exercise

Trial Locations

Locations (1)

University of Colorado Hospital; 🇺🇸 Aurora, Colorado, United States