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

Therapuetic Areas:Rheumatology
Age Range:60 - 80
Start Date:November 2015
End Date:December 2018
Contact:Sarah J Wherry, PhD

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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.

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

- 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
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Aurora, Colorado 80045
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