Parameters of Exercise to Prevent Osteoporosis

Not Applicable

Completed

• Conditions: Osteoporosis, Postmenopausal

• Registration Number: NCT04063813
• Lead Sponsor: University of Michigan

Brief Summary

The principal goal of this study is to determine parameters of walking in terms of peak mechanical vertical force, bout duration, and bout spacing that can preserve or increase bone mineral density (BMD) in postmenopausal women. Release of pulses of parathyroid hormone (PTH), growth hormone (GH), and of markers of bone resorption and bone formation will be used as indicators of the osteogenic effects of a short exposure to exercise. When secreted in pulsatile fashion, GH stimulates osteoblast proliferation, particularly in cortical bone (27, 28). Like GH, the pattern of PTH secretion determines the nature of its effect on bone. When it is secreted in pulsatile manner, PTH contributes to bone formation through activation of bone lining cells, differentiation of osteoprogenitor cells, and suppression of bone cell apoptosis .

Detailed Description

A. Hypotheses and specific aims:

Specific aim 1. Measure plasma concentrations of anabolic hormones (parathyroid hormone (PTH) and growth hormone (GH), at sufficient frequency to define the area under the curve (AUC), and of markers of bone formation (osteocalcin, carboxyterminal propeptide of type 1 procollagen (CICP), and bone-specific alkaline phosphatase (ALKP)), and markers of bone resorption (immunoreactive carboxyterminal telopeptide of type I collagen (CTX)) after 40-minutes of treadmill exercise at the relative intensity of 125% of the ventilatory threshold (VT) corresponding to about 1.78 m/sec (4 miles/h), and two intensities of mechanical loading (724, and 1411 N), in healthy postmenopausal women.

Hypothesis 1. Bone formation, as assessed by increases in markers of bone formation and decreases in markers of bone resorption, will be higher in response to dynamic exercise at a level of mechanical loading that produces increased secretion of PTH and GH than to exercise at other loading intensities.

Specific aim 2. Measure plasma concentrations of anabolic hormones), at sufficient frequency to define the area under the curve (AUC), and of markers of bone formation as in specific aim 1, after two 20-minutes of treadmill exercise, separated by 7 h, at the relative intensity of 125% of the ventilatory threshold (VT) corresponding to about 1.78 m/sec (4 mi/h), and two intensities of mechanical loading (724, and 1411 N), in healthy postmenopausal women.

Hypothesis 2. A 7-hour interval separating the two bouts of exercise will have greater bone anabolic effect than the equivalent volume and intensity of exercise performed in a single bout.

Study Timeline

• Study Start: 2007-05-15
• Primary Completion: 2010-08-19
• Study Completion: 2010-08-19
• Status Verified: 2019-08
• Study First Submitted: 2019-08-19
• Study First Submitted QC: 2019-08-20
• Last Update Submitted: 2019-08-20
• Study First Posted: 2019-08-21
• Last Update Posted: 2019-08-21

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 40

Inclusion Criteria

• Age 50 to 65 years if naturally post-menopausal, or age 47 if surgically postmenopausal
• Dual energy X-ray absorptiometry (DEXA) Z score above -1
• No endocrine or metabolic disease requiring medication except for hormonally corrected hypothyroidism
• No musculo-skeletal disabilities that would preclude treadmill walking
• Normal electrocardiogram (EKG) and heart health history
• BMI between 24 and 30
• Hematocrit above 32 %
• No hormone replacement therapy (HRT)
• Personal health provider's Release Letter

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Exclusion Criteria

• Age and BMI outside of the specified range
• Z score below -1
• Medication for presence of metabolic or endocrine disease
• Musculo-skeletal disabilities that would preclude treadmill walking
• Abnormal electrocardiogram (EKG) and heart health history
• Hematocrit below 32%
• Hormone replacement therapy
• Failure to conform to study protocol

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Serum osteocalcin	Hourly blood draws between 8:00 and 22:00 hours	Concentration of osteocalcin measured in serum samples
Ground reaction forces	During last 5 minutes of treadmill walking	Sum of pressures on mechanosensitive Novel-Pedar shoe insoles
Serum CICP (c-terminal propeptide of type 1 collagen	Hourly blood draws between 8:00 and 22:00 hours	Concentration of CICP measured in serum samples
Serum CTX (c-terminal telopeptide of type 1 collagen	Hourly blood draws between 8:00 and 22:00 hours	Concentration of CTX measured in serum samples

Secondary Outcome Measures

Name	Time	Method
Serum cortisol	Hourly blood draws between 8:00 and 22:00 hours	Concentration of cortisol measured in serum samples
serum PTH (parathyroid hormone)	Hourly blood draws between 8:00 and 22:00 hours	Concentration of PTH measured in serum samples
Relative aerobic capacity	1 day (measured throughout treadmill exercise bouts)	Percent of maximal aerobic capacity used during uphill and downhill exercise
Serum insulin	Hourly blood draws between 8:00 and 22:00 hours	Concentration of insulin measured in serum samples
Serum GH (growth hormone)	Hourly blood draws between 8:00 and 22:00 hours	Concentration of GH measured in serum samples

Trial Locations

Locations (1)

Michigan Clinical Research Unit United States; 🇺🇸 Ann Arbor, Michigan, United States