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

NCT ID: NCT02580604

Last Updated: 2025-08-13

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 12 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2015-11-30
• Study Completion Date: 2025-07-31

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.

Conditions

Osteoporosis

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: PREVENTION
• Blinding Strategy: NONE

Study Groups

Calcium Infusion followed by Saline Infusion

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.

Group Type: EXPERIMENTAL

Calcium Chloride/Calcium Gluconate

Intervention Type: DRUG

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.

Half-Normal Saline

Intervention Type: DRUG

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.

Interventions

Calcium Chloride/Calcium Gluconate

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.

Intervention Type: DRUG

Half-Normal Saline

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.

Intervention Type: DRUG

Eligibility Criteria

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

• Minimum Eligible Age: 60 Years
• Maximum Eligible Age: 80 Years
• Eligible Sex: FEMALE
• Accepts Healthy Volunteers: Yes

Sponsors

National Center for Advancing Translational Sciences (NCATS)

NIH

Sponsor Role: collaborator

University of Colorado, Denver

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Sarah J Wherry, PhD

Role: PRINCIPAL_INVESTIGATOR

University of Colorado, Denver

Locations

University of Colorado Hospital

Aurora, Colorado, United States

Countries

United States

Provided Documents

Document Type: Study Protocol and Statistical Analysis Plan

View Document

Other Identifiers

UM1TR004399

Identifier Type: NIH

Identifier Source: secondary_id

View Link

15-0878

Identifier Type: -

Identifier Source: org_study_id